Model Engine Maker

Engines => From Kits/Castings => Topic started by: tangler on April 09, 2013, 11:04:53 PM

Title: ETW's Wyvern Gas Engine
Post by: tangler on April 09, 2013, 11:04:53 PM
Hi Folks,

I've taken the plunge and ordered the castings and drawings for Edgar Westbury's  Wyvern gas engine from Hemingway today.  I'm hoping that telling you guys about it will discipline me to take this to completion in a (reasonably) short time.  Has anybody any experiences with the engine?  I'm tending towards gas (rather than petrol) as fuel.

I'll keep you posted.

Rod
Title: ETW's Wyvern Gas Engine
Post by: ths on April 10, 2013, 01:15:20 AM
No experience with it, but I'm looking forward to seeing you build it.

Hugh.
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on April 10, 2013, 01:54:28 AM
Looking forward to it Rod!

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on April 10, 2013, 01:55:16 AM
Again Rod, no specific experience, but if you are going with gas, I do have the drawings for regulators and demand valves, for when you get that far.


John
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 10, 2013, 07:24:16 AM
I have a set of his Centaur castings maturing in my collection  8)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 10, 2013, 11:21:18 AM
John,

Thanks for the offer, I'll take you up on that when the time comes.

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: michaelr on April 10, 2013, 02:27:32 PM
Just finished building my Wyvern, it's a fairly straight forward build but I had some issues, the main bearing oilers have to be reduced in diameter to clear the crank webs, you may have to modify the side shaft bearing at the skew gear end to get clearance for the gear, and the fixing positions.

I made the exhaust valve seating the same as the intake valve, using valve pockets (picture attached) this makes it easier to remove the valve for regrinding, I also seated the valve pockets using O rings.

Mike.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 11, 2013, 01:16:47 PM
(http://i104.photobucket.com/albums/m180/rod_sally/wyverncastings_zps10b17faa.jpg)

Here are the castings.  Good quality sand castings, they look like they've been pickled after fettling.  Nice prompt service from Hemingway.  I ordered the castings only set as I want to make the gears myself so I now need to study the drawings to find out what other materials I need and think about how I will make the crankshaft.

Mike, thanks for the heads up, I'll bear your comments in mind.  ETW's oilers aren't particularly elegant, I might do something else.
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on April 11, 2013, 03:56:21 PM
Those castings look nice!

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on April 11, 2013, 04:17:25 PM
Rod

Looks like an interesting build.  I will be following you along.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 17, 2013, 10:32:07 PM
OK, here we go - any comments, criticisms, advice and "whoa there, don't do it like that"will be very welcome!

Mr Westbury didn't think you needed to do much to the aluminium sub-base but then he didn't expect the maker to have a milling machine.  The top of the sub-base has a moulding number  cast in so this does have to be removed.  I sanded of the worst of the casting bumps on a piece of sand paper on the surface table so the base didn't rock.

(http://i104.photobucket.com/albums/m180/rod_sally/subbase1_zps0116d12e.jpg)

Pretty straightforward the to mill the top surface with a 1/2" endmill

(http://i104.photobucket.com/albums/m180/rod_sally/subbase2_zps43e305b4.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/subbase3_zpsfa742e5c.jpg)

I the turned the sub-base over to mill the base but couldn't juggle the position/clamps on the table to be able to cover the whole base with the end mill so resorted to my only shell mill.

(http://i104.photobucket.com/albums/m180/rod_sally/subbase4_zpsac3c2c93.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/subbase5_zps4e61d4a1.jpg)

Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on April 17, 2013, 10:40:25 PM
Great start Tangler!

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: tel on April 17, 2013, 10:43:00 PM
Off to a fine start - keep 'er going!
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 17, 2013, 10:50:00 PM
The main bed plate needs to have a good flat bottom to sit on the sub-base.  Very awkward to hold on the milling table so I reckoned it would be quicker to file it flat to the surface plate rather than make a fixture.  No pics I'm afraid - I seemed to get very blue! 

The bearing cap seats are machined at 30 degrees.

The head rotates on my mill and there is a taper pin that re-locates the head back to exactly 90 degrees so no worries there

(http://i104.photobucket.com/albums/m180/rod_sally/milltaperpin_zps733080c0.jpg)

In this configuration the milling cutter needs to cover the whole width of the cut so I continued with the shell mill

(http://i104.photobucket.com/albums/m180/rod_sally/mainbedplate1_zps159b8b11.jpg)

The centre of the bearing was popped, the seat needs to be milled down to this mark

(http://i104.photobucket.com/albums/m180/rod_sally/mainbedplate2_zpsc15b43e5.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/mainbedplate3_zpsed08727b.jpg)

Bearing caps next...

Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on April 17, 2013, 11:52:52 PM
Tangler,

If I could make a suggestion, hopefully before you go any further.

DO NOT trust that the castings are correct. Get them on your surface plate and using either a height gauge or scribing block, check that the castings are the correct height from one side to another, square where square should be, parallel in the right parts, say to the main base etc.

You must get an accurate datum on each main part before going any further.

If that isn't carried out, you run the risk of something becoming twisted or not fitting later.

Once you have your datum, and got it machined, then everything else goes from that.

This is a very common mistake when beginners start out with castings, they think that they should fit together correctly, but in fact, they very rarely do, and making from castings can be a lot more difficult than making from barstock.

There must be thousands of sets of part made castings sitting under benches where someone has started before getting their datums set up first, then soon found out that things don't fit.

I am not trying to scare you or put you off, but do please be careful and don't have a cavalier attitude towards casting sets.

I have used Hemingway castings before, and they are not all they are made out to be, they require a fair amount of work and fiddling to get a well running and looking motor.

If you really want to see how a datum is set up, have a look at a bit of my post, here

http://www.modelenginemaker.com/index.php/topic,158.0.html

John
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 18, 2013, 07:09:03 AM
Rod,

Whilst I agree with John on the need for Datums, deciding what and where to place them on castings can be challenging. The problem is that whilst the dimensions of the casting should be right, they rarely are. There are lots of things that cause this: shrinkage due to the shapes of the pattern can drag the cast metal, worn patterns cause everything to be undersized, over enthusiastic people with angle grinders at the foundry.... :ShakeHead:.

So you need to find a reference that enables you to get the part out of the casting, then you work from that to identify a suitable datum for further work. Aim to get the bits that need machining out of the metal, you can always build up the cosmetic features using a filler or something. In the worse cases don't be frightened of altering measurements but make sure if you do that you also adjust their mating parts.  ;)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 18, 2013, 10:26:35 AM
John, Jo,

Thanks for the comments.  Castings are indeed, tricky chaps.

The important thing with the bed plate seems to be to get the axis of the main bearings at right angles to the cylinder axis and at the same centre height.  I've already assured myself that I can get the drawing dimensions out of the casting "envelope".  Fitting the bearings caps is really just adding to the casting, it is only then that the real machining starts.  The plan is to machine the front bearing face for the cylinder jacket and then to use this as the datum to set up boring the main bearings at a right angle.  I'm not sure how I'm going to do this yet.  If it all fits I may use the mill as a horizontal borer but otherwise there are a couple of other options.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on April 18, 2013, 01:26:32 PM
Rod,

I looked at the website to get a feel for what the final engine will look like....very nice I must say.  John and Jo both make good points as to castings but you seem to have a bead oh how to proceed and I will certainly enjoy following along on the journey.

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on April 18, 2013, 01:31:08 PM
Rod,

No problems.

I just wanted to let you and others know that sometimes life isn't as easy as it seems if you want a good result.

BTW, Jo raised a very good point about over fettling in the foundry. On my last set of castings from Hemingway, after almost completing the engine, I had to get a friend build up the front of the main upright cylinder casting by 1/4" with ali weld, so that the cylinder head would fit in the correct position. They certainly had a gorilla on duty that day.

I always prefer to have no fettling done at all, at least then, it is only your fault that causes the problem.


John
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 18, 2013, 07:58:42 PM
Making and fitting the bearing caps.  They come as a cast stick of 2 so I separated them with a hacksaw (this could probably have waited till after the next stage).

(http://i104.photobucket.com/albums/m180/rod_sally/sawcaps_zps77e0f532.jpg)

Then a light skim across the bottom

(http://i104.photobucket.com/albums/m180/rod_sally/capskim_zps80694ac4.jpg)

Each cap was then snugged down on to a length of gauge plate (ground flat stock), acting as a parallel, in the milling vice.  A best guess was made as to where in the casting the centre is located and the DRO zeroed

(http://i104.photobucket.com/albums/m180/rod_sally/centre1_zps2763b54d.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/centre2_zpsfee17816.jpg)

holes were spotted with a centre drill at 7/8" centres using the DRO and then spot faced with a 1/4" slot drill

(http://i104.photobucket.com/albums/m180/rod_sally/spotface_zps4f9f93c2.jpg)

centre spots drilled out to 4BA clearance on the pillar drill (I feel more comfortable doing this with small drills than on the mill - the downside of not having a quill)

(http://i104.photobucket.com/albums/m180/rod_sally/drillcap_zpsaba55c4c.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/fincaps_zpsb141ba5e.jpg)

Now to drill the holes in the bed plate.  Mounted on the tilting table and levelled (if I dare use that jargon ;) ) using a DTI

(http://i104.photobucket.com/albums/m180/rod_sally/capseat1_zps9a5c5862.jpg)

I used the DRO to put spots at the correct spacing

(http://i104.photobucket.com/albums/m180/rod_sally/capseat2_zps1d8c8d56.jpg)

Although it's inconvenient to move the job to the pillar dril to enlarge the centre spots to 4BA tapping...

(http://i104.photobucket.com/albums/m180/rod_sally/capseat3_zps1dff1da9.jpg)

at least it's close to the tapping guide!

(http://i104.photobucket.com/albums/m180/rod_sally/capseat4_zpsab1fb22d.jpg)

Temporary attachment of the bearing caps to the bed plate, ready to be trued up with the rest of the casting

(http://i104.photobucket.com/albums/m180/rod_sally/platewithcaps_zpscd6ca412.jpg)

I'm pretty comfortable that the caps are where they should be relative to the base and front of the bed plate.  The picture demonstrates what John and Jo mentioned earlier: the casting isn't as symmetrical and accurate as one might hope so the nearer cap looks misplaced.  A bit of work with a file will sort that out prior to painting.








Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 22, 2013, 07:55:52 PM
Apologies folks, I managed to take an afternoon's worth of pictures with no card in the camera :-[

(http://i104.photobucket.com/albums/m180/rod_sally/finbase1_zps92c4f1c3.jpg)

I did use the mill in horizontal mode, there was just room to get the job and my boring head in the Y travel.  I milled the front face where the cylinder locates and then zeroed the table with the horizontal axis.  I was then able to lower the table to give the 1 3/8" height to the cylinder axis.  There wasn't room to get a drill and chuck in front of the casting so I started the hole off with a 1/2" slot drill and then opened it out to 5/8" with the boring head. 

(http://i104.photobucket.com/albums/m180/rod_sally/finbase2_zps577a89f9.jpg)

The casting was rotated through 90 degrees and set up absolutely square with the aid of DTI on the newly machined front face.  Using the DRO I was then able to bore the main bearing hole through the casting and cap at exactly cylinder centre height and 4" from the front face as per drawing.  I also faced the mounting for the cam shaft bearing on the nearside main bearing support.  The casting was rotated through 180 degrees and the procedure was repeated with the boring head at the same offset for the other bearing hole.

(http://i104.photobucket.com/albums/m180/rod_sally/finbase3_zpsc0d5725a.jpg)

Finally, with the mill back in vertical mode, the caps were tidied up, oiler mounts faced and the hold down bolt pads spot faced.

The seatings for the bronze bearings still need to be machined but I want to wait until the crankshaft is made before finalising the gap between the bearings and fitting the bronze bushes.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 24, 2013, 06:33:40 PM
The cylinder liner locates the cylinder jacket assembly in the hole in the bed plate so I've tackled this next.  The liner is made from a length of 40mm OD cast iron.  I decided to use the 4 jaw SC chuck to give good support as there is 4" overhang.  I parted off to length (leaving enough to make the piston rings) and used a left hand tool to turn a bit truly round for mounting in the chuck for turning the OD and the bore.

(http://i104.photobucket.com/albums/m180/rod_sally/liner1_zps38579c58.jpg)

Turning the OD was straight forward and there is a 1/16" flange at the headstock end that will locate in the cylinder head

(http://i104.photobucket.com/albums/m180/rod_sally/liner2_zps98a15d20.jpg)

I drilled a pilot hole with a 5/16" drill and followed this up with my favourite "opener out", a 3/4" drill with a 2MT shank

(http://i104.photobucket.com/albums/m180/rod_sally/liner3_zps55c61999.jpg)

I followed this up with my biggest drill, a 1" blacksmith with 1/2" shank

(http://i104.photobucket.com/albums/m180/rod_sally/liner4_zps06df6a04.jpg)

Boring came next.  The hole needs to be about 4" deep.  So I set up as shown to give as much support to everything as I can.  I used my Gibralter toolpost (courtesy of Tubal Cain and Hemingway) and set the fixed steady as close to the cross slide as I could.

(http://i104.photobucket.com/albums/m180/rod_sally/liner5_zpse1384978.jpg)

 I have a choice of 3 boring bars that can reach in 4".  The one on the left has a TC tip.  It chattered horribly at all feeds and speeds.  The middle bar has an inset HHS tip and this vibrated even more.  Fortunately the one on the right seemed to do the trick.  This is HSS but, judging by the marks left by the toolpost screws is much harder all through than the shank of the TC tool and is therefore stiffer, even though I imagine that the HSS is welded to a steel shank.

(http://i104.photobucket.com/albums/m180/rod_sally/liner6_zpsb4d83ac4.jpg)

The final task is to machine the chamfer that will ease insertion of the piston with rings

(http://i104.photobucket.com/albums/m180/rod_sally/liner7_zps46ca9a1a.jpg)

Turning completed

(http://i104.photobucket.com/albums/m180/rod_sally/liner9_zps9a58c959.jpg)

The finish feels fine but, as you can see, is made up of very fine chatter marks.   Careful measurement shows that the headstock end (cylinder head) is 1/2 thou smaller than the other end.  Lapping should sort out these issues.  ETW suggests lapping once the liner is mounted in the jacket so that will come later

(http://i104.photobucket.com/albums/m180/rod_sally/liner8_zps8daecdb6.jpg)

In the past, on smaller engines, I've used an aluminium split lap mounted on a taper and some valve grinding compound (fine at one end of the tin and coarse at the other).  Is that the best way forward or are their better methods to get a truly smooth and parallel bore?







Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on April 24, 2013, 07:06:51 PM
You might consider a brake cylinder hone to get some of the worst of it out and then switch to the lap. The hone may help with the slight taper as well.

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 24, 2013, 08:27:25 PM
Cheers Biil,

I have wondered about these http://www.pollymodelengineering.co.uk/global/technical-notes/cylinder-hones.asp (http://www.pollymodelengineering.co.uk/global/technical-notes/cylinder-hones.asp) from time to time but have always been dubious about whether they will make the bore truly round and parallel.  Seems easier than lapping if they do.
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on April 24, 2013, 08:40:54 PM
The one I have is like the lower one in the picture. There are some good pointers on that link as to using them and like any tool, if misused the results will show it. I think the main thing is to keep the hone moving up and down the length of the cylinder evenly and with plenty of lubrication to keep the stones from clogging up and as noted NOT letting the pivot go beyond the end of the cylinder.  Maybe others will chime in here with more experience using these. I have only done it with two cylinders but with good results.

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on April 25, 2013, 04:13:23 AM
Tangler,

The ones from Polly are way too expensive.

You can get a 4 in 1 set from Sealey for around £20, and they work great for honing out bores to parallel and roundness.

I have used mine many times, and they do a great job.

http://www.amazon.co.uk/Sealey-VS029-Cylinder-Hone-4-in1/dp/B000RO7THQ/ref=sr_1_3?ie=UTF8&qid=1366859414&sr=8-3&keywords=cylinder+hone

John
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 25, 2013, 06:49:33 AM
Bill & John,

Thanks guys, I'm convinced.  Ordered from John's link with "1-click" .

It's great here, I love it,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 25, 2013, 09:00:48 AM
 :noidea: Ok I have just read the guidance notes on the Polly website and it says to rotate the hone only in a clockwise direction: a Lathe chuck rotates anticlockwise, so does a drill chuck. Am I missing something?  :shrug:

I have always used my hones in an anticlockwise direction  :headscratch:.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tel on April 25, 2013, 09:15:55 AM
With the hone in the tailstock chuck it is, in effect, rotating clockwise, even tho it's not moving
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 25, 2013, 09:20:30 AM
That means that the cylinder will need to be in the chuck. I often hold the cylinder in my hand  ::) or rest the bigger cylinders on the cross slide:

(http://i214.photobucket.com/albums/cc12/jothoms/Double%20Tandem%20Compound/honing.jpg)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Tennessee Whiskey on April 25, 2013, 09:22:03 AM
I think if you look from the driven end both lathe and drill chucks are turning clockwise. I am not sure, but, I think this is the way rotation is noted. You have been right all along if this is correct.

Yo Redneck,
Eric
Title: Re: ETW's Wyvern Gas Engine
Post by: Maryak on April 25, 2013, 09:31:05 AM
That means that the cylinder will need to be in the chuck. I often hold the cylinder in my hand  ::) or rest the bigger cylinders on the cross slide:

(http://i214.photobucket.com/albums/cc12/jothoms/Double%20Tandem%20Compound/honing.jpg)

Jo

And...................relative to the cylinder which way would you say the hone is rotating if the lathe is in "Normal" forward gear?
Title: Re: ETW's Wyvern Gas Engine
Post by: Tennessee Whiskey on April 25, 2013, 09:36:35 AM
Clockwise. I guess that is what I was trying to say. May have just came out in redneck terms.

Eric
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on April 25, 2013, 10:15:55 AM
Jo you must be running the hone clockwise as the various ends fit onto a standard R/H thread, if you were running the hone anti-clockwise the end would come unscrewed.

I tend to use the drill press and hold the liner in my hand

(http://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Half%20scale%20Domestic%20Stovepipe/IMAG0342.jpg)

J
Title: Re: ETW's Wyvern Gas Engine
Post by: tel on April 25, 2013, 11:05:43 AM
Quote
That means that the cylinder will need to be in the chuck. I often hold the cylinder in my hand  ::) or rest the bigger cylinders on the cross slide:

Where it will still (viewed from the back end of the hone) be rotating clockwise
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 25, 2013, 11:26:06 AM
Ok it goes clockwise  :ThumbsUp:.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on April 25, 2013, 11:58:52 AM
Jason,

I am curious as to the concoction you are using there in that little cup? Almost looks like the beginnings of a pesto sauce but I know that can't be it :)

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 25, 2013, 12:01:20 PM
I am curious as to the concoction you are using there in that little cup? Almost looks like the beginnings of a pesto sauce but I know that can't be it :)

I assumed that he had been using it to catch swarf curls in  :ROFL:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on April 25, 2013, 01:14:35 PM
Tangler,

The ones from Polly are way too expensive.

You can get a 4 in 1 set from Sealey for around £20, and they work great for honing out bores to parallel and roundness.

I have used mine many times, and they do a great job.

http://www.amazon.co.uk/Sealey-VS029-Cylinder-Hone-4-in1/dp/B000RO7THQ/ref=sr_1_3?ie=UTF8&qid=1366859414&sr=8-3&keywords=cylinder+hone

John

John

I am not convinced that the results of using a spring loaded hone will give a truly accurate parallel and round bore. If anything the stones will tend to follow the shape they are spring loaded against.
These hones are great for "glaze busting" when cleaning up old cylinders, but not for correcting errors.

A delapena type hone uses a completely different method of applying pressure and guidance to the abrasive stone, this ensures only the "high spots" are removed and the stone does not remove material from the troughs as well.
This is an interesting website with some good info. http://www.delapena.co.uk/honing.html

I was extremely lucky recently in finding a Delapena "external" hone for doing outside diameters on shafts, I will be using it to finish the valve spindles on my Pollit & Wigzell Corliss engine.
http://thebloughs.net/hobbies/metalworking/ext_hone/

Just my 2p worth
Phil

Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on April 25, 2013, 01:19:09 PM
Phil: Bruce engineering (now Polly Engineering) do kits for those as well. I used mine to do the R&B  :ThumbsUp:.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Ramon Wilson on April 25, 2013, 02:01:25 PM
Hi guys, 

Have to agree with Phil here - the two or three stone cylinder hones will not true up an out of round or tapered bore - it doesn't take much to see that spring loaded, they will just follow the bore.  I have a Delapena external hone which does true the bore but this is an entirely different kind of hone. If a hone of that sort is not available then the best way of truing a bore with the usual kit at our disposal is to make a lap and use compound. At a push valve grinding paste as mentioned can be used but is a bit coarse - even the fine end - but silicon carbide powders are available in a range of grits - I have 240 thru 1000 which is mixed with a drop of thin oil.

Diamond paste is much more readilly available however a note of caution - if using this on soft material, ie unhardened, then the part needs cleaning in an ultra sonic cleaner to rid the surface of particles which will have embedded. Washing in the usual solvents - paraffin etc will not do this completely. Maybe not so important in a steam engine bore but in an I/C engine an ideal aid to running in - and out again  ;)

Ramon 
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on April 25, 2013, 04:22:26 PM
This time I will disagree with you.

Surely this isn't another case of the loadsa money gets better results brigade?

OK if you have the money to buy expensive specific bore internal hones, but think of the average man in a workshop, and there must be thousands of us out here using this type, who swear by them.

If they are used correctly, they WILL get rid of tapers in bores, and low measurements down the bores after boring, because I have done it, many times, and will continue to do so in the future.

Jo, I too have bought some of those external hone castings from Polly, they must work out a lot cheaper than Delapena. Do they work OK?

Ramon, there is a big difference between honing and lapping, similar process, but definitely not the same.
Lapping an i/c engine bore shouldn't really be done, it should be honed (to break glaze and to straighten out any imperfections), then allow the piston and cylinder to bed themselves in during normal running in.
I only lap when a superfine surface is required, Stirling engines, flame lickers, steam engines etc.

BTW, how does your Delapena external hone clean up an internal bore, are you holding back on us?


John



           
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on April 25, 2013, 04:33:59 PM
Jason,

I am curious as to the concoction you are using there in that little cup? Almost looks like the beginnings of a pesto sauce but I know that can't be it :)

Bill

Parafin (kerosene) just feed a small amount into the cylinder and it stops the stones clogging. There is quite a bit of aluminium swarf in teh bottom as I use it as a cutting fluid on ali.

I have used them to take out a slight taper, just play the home where the dia is smaller and keep taking measurements until its the same all the way through. They won't correct a mis shaped bore though.

Lapping pistons into lapped cylinders is common practice on small glow and diesel aero engines, not sure where you got that from John.

MEB had an article and drawings a while ago for making the external delapena type hones.

http://www.modelenginebuilder.com/issuetwentyfive.htm
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on April 25, 2013, 05:19:32 PM
Sorry Jason, I was on about ones with rings, like Jo's R&B.

But I did also straighten out the bore on my Scott flame licker with one of these honing kits, when I had a high spot in the middle of the bore.



John
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 25, 2013, 05:27:17 PM
Thanks for all the input guys.  Clearly a difference of opinion.  At less than £20 quid it's going to be a cheap experiment - I can always fall back on the home made lap.

One other question (for the moment).  The piston is an ally casting, I'm guessing LM4 and will have 2 cast iron rings.  The co-efficient of linear expansion of LM4 is about twice that of the cast iron cylinder so I feel I ought to leave a bit of a gap when cold - but how much?

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Ramon Wilson on April 25, 2013, 05:32:35 PM
Hi John - Don't be too quick to condemn - I am well aware of the difference between lapping and honing  ;) but first though - a Freudian slip - my 'external' Delapena should have read 'Internal' Secondly we are talking about 'trueing' a bore not the surface finish.

Now before we get into a slanging match about owning expensive kit as well, I have one lathe bought 1980 - a Myford S7, one mill - an old Linley, a drill - Fobco four speed (fixed spindle no MT) and a couple of bench grinders. Throw in the bandsaw and the recently acquired bead blaster I'm not exactly tooled up as some would profess to be.

As well as this about two years ago I bought a very old but serviceable bench mounted Delapena hone at a very reasonable cost from Polly engineering.  I have managed to find some tooling for it but as yet none that matches what I have been doing of late. So far it has sat idle then and everything done cylinder wise has been lapped, besides which, the type of engines I have been making require a lapping process to acheive the kind of fit required. To 'compliment' this I also managed to get two beautiful and previously unused sets of Delapena external hones again at a good price off ebay.

I have had for many years the two stone and three stone hones as sold by Polly and do use them - but not to true a bore. The only way a tapered bore can be trued with them is to dwell in the tight area - yes that's possible I would agree - though not exactly scientific but if the the bore is out of round how on earth do the sprung loaded legs take the high spots off without affecting the low spots.

A well made lap on the other hand - easily within the reach of most of us to make will true a bore at little expense save time and produce an extremely accurate and round bore within the remit of what most of us have at our disposal. I think it would be fair to say the compression on the engines made so far would speak for that. Once the bore is trued of course then the sprung loaded hones can be used if desired to provide the oil retentive surface you describe.

The external hones were bought with the fine tolerances of shaft bearing locations in mind as well as pistons and contra pistons. So far these have not proved particularly beneficial in the former operation due to working up to a shoulder. I have as yet to try them on a piston and the contra pistons are rather narrow relative to the stones so rocking can occur - so far I have kept to lapping these items with good success and the bearing surfaces acheived by careful application of wet and dry backed with something truly flat. So far then it looks like my outlay, though reasonable, has not exactly gained a return.

I have to say John that at all times I do try to bear in mind that most on here, probably for the greater part, have very limited resources (equipment) at their disposal - and as such if a manner in which something can be acheived at little cost - either in time, skill or money as a means to an end then that has to be far more better than 'Loadsa money getting results' - if I thought I give that impression at any time I would be most remorse.

Regards - Ramon
Title: Re: ETW's Wyvern Gas Engine
Post by: ScroungerLee on April 25, 2013, 05:34:50 PM
I have used the spring loaded 3 stone hones, often called brake hones when sold to refinish the hydraulic cylinders in drum brakes.  Obviously they don't magically fix a tapered cylinder, you need to spend a bit more time honing the places you know are too small, along with frequent careful measurements.  Also, never let the hone stay in one place while turning, it has to always be moving back and forth through the cylinder at least a small amount.

Just my 2 small coins of little worth.

Lee
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on April 25, 2013, 05:50:58 PM
One other question (for the moment).  The piston is an ally casting, I'm guessing LM4 and will have 2 cast iron rings.  The co-efficient of linear expansion of LM4 is about twice that of the cast iron cylinder so I feel I ought to leave a bit of a gap when cold - but how much?

I'd go about 0.003" per 1" dia, not sure without looking what the Wyvern is but you would probably want the piston 0.005" smaller assuming its 1.5" dia

J
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 25, 2013, 06:05:15 PM
The cylinder jacket is an ally casting.  ETW says that it should have a cast in relieved bore to act as the water space but mine hss a parallel cored bore.  The casting is not particularly round and the ends are a bit mis-hapen but there is room to get the job out of it.

The casting was mounted in the 4 jaw and I used my rotating centre to get the cored hole somewhere near the middle and checked that the body was not too eccentric.

(http://i104.photobucket.com/albums/m180/rod_sally/jack1_zpsfa8219bd.jpg)

I took a facing cut with the centre still in

(http://i104.photobucket.com/albums/m180/rod_sally/jack2_zpsc3fe4c84.jpg)

and then finished off the facing very gently with no tailstock support.

(http://i104.photobucket.com/albums/m180/rod_sally/jack3_zps61f00425.jpg)

I the turned the casting around so that the machine face was butted up against the chuck face and repeated the operation.  The casting was turned again and a trial cut was taken with the boring tool.  This showed that the bore was tilted because the cut was tapered.

(http://i104.photobucket.com/albums/m180/rod_sally/jack4_zps0e385ed7.jpg)

I used a bit of shim under one side to bring the bore to more nearly vertical and now had confidence that the bore would be pretty much be central to the casting. 
(http://i104.photobucket.com/albums/m180/rod_sally/jack5_zps8aca5c3b.jpg)

I faced the end and then turned it around so that the the square end, which is the one that buts up to the main bed plate, was at the outboard end.  The bore was turned to size and a final facing cut made, ensuring that the bore would be at right angles to the bed plate.  I now had to turn the recess for the water space.  This was slightly alarming because I have no method of measuring the wall thickness directly but the outside of the cylinder seemed to be reasonably concentric so I went for it and bored a 0.1" deep recess using this tool.  Feeding straight in to from a groove using the cross slide was surprising painless and then the recess was bored as normal

(http://i104.photobucket.com/albums/m180/rod_sally/jack7_zps98549727.jpg)

The bored jacket

(http://i104.photobucket.com/albums/m180/rod_sally/jack8_zpsd6a19457.jpg)

and the cylinder liner inserted

(http://i104.photobucket.com/albums/m180/rod_sally/jack9_zps23408eaa.jpg)


(http://) 

Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 25, 2013, 06:09:58 PM
One other question (for the moment).  The piston is an ally casting, I'm guessing LM4 and will have 2 cast iron rings.  The co-efficient of linear expansion of LM4 is about twice that of the cast iron cylinder so I feel I ought to leave a bit of a gap when cold - but how much?

I'd go about 0.003" per 1" dia, not sure without looking what the Wyvern is but you would probably want the piston 0.005" smaller assuming its 1.5" dia

J

Wyvern is 1.250" bore.  I've used 4 thou on an air cooled 1" glow engine before but I'm assuming this water cooled thumper won't get as hot.  3 or 4 thou seems reasonable.

Thanks,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on April 25, 2013, 06:23:40 PM
Nice work on that Rod. You are probably happy to get that behind you!! Still following along with interest here.

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 26, 2013, 10:08:35 AM
Bill & John,

Thanks guys, I'm convinced.  Ordered from John's link with "1-click" .

It's great here, I love it,

Rod

Sometimes, Amazon can be just a little scarey  :o

(http://i104.photobucket.com/albums/m180/rod_sally/hone_zps9a822a94.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on April 27, 2013, 12:04:41 PM
Looks great Rod!....Navigating the "nuance" of a casting is a challenge at times!..You persurvered and got there wonderfully!

 :praise2:

That is patience...and persistance.....Well done!



I have to agree Ramon, a good simple lap will straighten a bore.   Lapping is a process as old as the hills, and when done correctly, works wonderfully, and won't leave behind anything that will damage mating parts.  Machine tool manufacturers have been doing it for centuries.  Ask Johanson. 

I have the same drawings for the hone....its on the "roundtuit" list...maybe in 132 years or so... ;D
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 27, 2013, 08:32:48 PM
Honing.  Here's the controversial item ready to attack the cylinder liner

(http://i104.photobucket.com/albums/m180/rod_sally/hone1_zpsa6723d16.jpg)

I did this in the lathe, holding the liner whilst the hone rotated at a slowish speed, liberally lubricated with my standard cutting fluid which is Cutmax diluted 50:50 with paraffin.

(http://i104.photobucket.com/albums/m180/rod_sally/hone2_zpse6e60126.jpg)

About 10 mins honing was sufficient to remove all the chatter marks.  The lighting emphasises the scratch marks - the bore seems very smooth

(http://i104.photobucket.com/albums/m180/rod_sally/hone3_zps5c8b78e8.jpg)

I used my telescope gauges and digital vernier to measure the bore at both ends and in the middle.  Several measurements in nominally the same place were gratifyingly consistent.

(http://i104.photobucket.com/albums/m180/rod_sally/hone4_zps51e1327c.jpg)

The resolution is just 1/2 thou

(http://i104.photobucket.com/albums/m180/rod_sally/hone5_zps61180ae6.jpg)

When I was happy that the chatter marks had disappeared, measurement showed that the cylinder head end was 1/2 thou larger than the other end which is unacceptable.  A further ten minutes honing concentrating, but not exclusively, at the crankshaft end reversed the situation with the head end now 1/2 thou smaller which I am happy to accept.

So is this tool successful?  A qualified yes.  It is certainly quicker than making a lap and there is less danger of damaging the lathe with a residue of abrasive slurry.  With multiple laps (or using a fugitive abrasive) I would be able to get a finer finish if required and I would also expect to achieve a truly parallel bore but then, within the limits of my measurement, I could achieve this with further work with the hone.  A direct bore measuring system would make it easier to monitor progress.  I think the result is adequate for use with a piston with rings

I think I'll make the piston next:

Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on April 27, 2013, 09:55:35 PM
Glad it's working for you Rod!   That engine is really coming along...still following!
 :ThumbsUp:

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 27, 2013, 10:30:08 PM
Thanks for maintaining an interest.

I'd be very happy for people to chip in and criticise.  I'm sure I'm not necessarily doing things in the best way and if others have alternative methods to the ones I've described I'd be pleased to see them.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on April 27, 2013, 10:40:02 PM
Happy to see things worked out well Rod.

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on April 27, 2013, 10:57:56 PM
Thanks for maintaining an interest.

I'd be very happy for people to chip in and criticise.  I'm sure I'm not necessarily doing things in the best way and if others have alternative methods to the ones I've described I'd be pleased to see them.

cheers,

Rod

Hey Rod,
Very accomodating of you!   :praise2:
I would not have tried the brake hone, but had gone with the lap...but there are a 1000 ways to get it done....and getting done is all that matters.
I like what you have done, so no critizism at all here....just different approaches.

 :ThumbsUp:

Keep it coming man!

Dave
Title: ETW's Wyvern Gas Engine
Post by: ths on April 28, 2013, 07:39:56 AM
The hone worked really well, we'll done. One to remember.

Hugh.
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on April 28, 2013, 10:59:24 AM
Glad it worked out for you with the hone.  I have exactly the same one also from Amazon and it did a good job for me on my Kiwi cylinder liner.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 01, 2013, 08:23:46 PM
The piston.  This is a cored ally casting with internal gudgeon pin bosses and a chucking piece.  The first job was to trim up the chucking piece so there is something for the 4 jaw to have a firm grip on.

(http://i104.photobucket.com/albums/m180/rod_sally/piston1_zps83a72b04.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/piston2_zps8a83d0b9.jpg)

The piston was then turned around and the core hole centred (sort of) before tightening up the jaws


(http://i104.photobucket.com/albums/m180/rod_sally/piston3_zps7556d0dc.jpg)
The inner was trued up as far as the gudgeon pin bosses.  As I was turning the outside diameter I became aware that the the piston was skewed and had to be straightened up.  This made the outboard end eccentric and I became aware that there was grave danger that I wouldn't be able to bring the outer to the proper size (3 thou less than the cylinder) without going through one side of the piston. I managed to adjust the four jaw to bring everything back in bounds but the skirt is now rather thin.

(http://i104.photobucket.com/albums/m180/rod_sally/piston4_zpsf4eef82b.jpg)

To cap it all, as I started to take the last half thou cut to bring to size I became aware that I'd put on too large a cut, 5 1/2 thou instead of 1/2 thou, so the skirt is even thinner for 3/16" :-[

(http://i104.photobucket.com/albums/m180/rod_sally/piston5_zps73dea0fd.jpg)

Theses errors won't actually make any difference and I could probably cut the skirt off without any detriment to performance so I think I've just about got away with it.  Not a great perfomance!

I think I'll leave the piston ring grooves to a nice bright new day.
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on May 01, 2013, 08:32:40 PM
I have found chucking spigots on pistons can be quiet off so use a 3 stage machining method

1. hold by the top of the piston and adjust the 4 jaw so the cast inside runs true then skim the outside of the skirt area.

2. Turn around and hold by the skimmed skirt and turn the spigot true to that

3. You can then hold by the spigot and be sure the inside of the piston will be running true while you finish machine the ouside.

J
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 02, 2013, 05:21:39 PM
The piston now needs the ring grooves cutting in and the gudgeon pin hole making.
For the grooves the first step was to grind a 1/16" parting tool with 3 degrees top rake on the Worden

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston1_zps3d073a11.jpg)

Now to get some confidence and work out some speeds and feeds using a bit of gash ally

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston2_zpsd31dfc3b.jpg)

While the piston (in the 4 jaw) was out of the lathe it was mounted on the dividing head in the milling machine.

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston3_zps2e552975.jpg)

Somehow I've got to find the approximate centre of theses bosses for the gudgeon pin

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston4_zps9e0dc3b7.jpg)

The bosses were lined up vertically by eye

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston5_zpsedd47caf.jpg)

and then a bit of dead reckoning from the end and the diameter of the piston allowed me to spot face with a slot drill and then use a stub drill

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston6_zps73e7f85a.jpg)

Hole finished of with a 1/4" reamer

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston8_zps54b9da06.jpg)

Back in the lathe (I love screw on chucks) the ring groove were parted in without trauma.  I've made the ring groove 2 thou deeper than the finished id of the piston ring

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston9_zpsfa8abe94.jpg)

The piston was the parted off but I need to tidy up the top surface so I made a mandrel with a 1 degree taper

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston81_zps91e33f40.jpg)

and mounted the piston

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston92_zps511527aa.jpg)

The finished piston

(http://i104.photobucket.com/albums/m180/rod_sally/bpiston93_zpsbe5fa925.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on May 02, 2013, 06:17:39 PM
Just my way of doing things Rod.

To line up the internal castings ready for boring the gudgeon pin hole, I use a piece of metal or planed softwood jammed in between the two bosses, then clock off the face of the jammed in piece to get things exactly square to your mill axis. It is then very easy to use an edge finder or coax indicator to get the centre of the piston.

Then a fairly long cutter to put a face onto the inside faces of the bosses, repeat if you want, using the above method, if you think you are more than a few thou out of square, otherwise, it should be just fine to wack your hole through the piston and bosses. The bosses are usually a lot thicker than really required, so a few thou out of square will make no noticeable difference in the end.

John
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 02, 2013, 08:29:47 PM
John,

Thanks for the input - always welcome.  I've still to finish the inside faces of the bosses.  I'm tending to leave lots of bits without the final finish until I have enough made to see that everything lines up properly.  Once the crankshaft is made then I should be able to start fitting bearings and then finalising the length of the con rod to make sure the compression is correct and that the crankshaft is aligned correctly between its bearings.  At least, that's the plan.

cheers,

Rod   
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on May 02, 2013, 08:42:17 PM
The inner faces are not too critical, the Wyvern like a lot of other engines has a bigger gap between the faces than the width of the little end so it will be almost self aligning.

J
Title: Re: ETW's Wyvern Gas Engine
Post by: swilliams on May 03, 2013, 01:32:08 AM
I'm enjoying following your build Rod and it's coming along really nice.

Cheers
Steve
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on May 03, 2013, 02:28:28 AM
I'm enjoying following your build Rod and it's coming along really nice.

Cheers
Steve
Same here Rod, as I can add much input but can cheer you on.

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 03, 2013, 09:07:45 AM
Thanks for the encouragement guys
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on May 03, 2013, 11:17:25 PM
This post is meant to be both light hearted and informative, all of what you are about to read is nothing more than my own personal opinion, if you don't agree with it I don't mind that's just fine by me. Please do not respond if you think it might cause anyone to get upset, that is certainly not what this is about in any way. My previous post was deleted by the administrators because I had posted it in the wrong place and apparently two people disagreed with my opinion, so this is an attempt to try and get my point across in a different manner.

Firstly let me say to Tangler, you are doing a great job.

Anyway I have recently been working on a new experimental engine design that has some very unusual features, namely an oval cylinder bore which is bell mouthed at one end and slightly tapered. None of the dimesions are critical just as long as it does not end up round and parallel.

I have had many sleepless nights wondering how to do this and scoured the internet for information on how to produce this with the limited equipment at my disposal.
I dare say there will be some fancy expensive machine that would do this job with ease, but I wanted to be able to do it with the tools I already have.

Then I remembered some previous discussions on here and it was one of those lightbulb moments.........I could use my flexible three legged cylinder hone.

So here is how I did it:-

The first part was easy, and that was to produce a relatively round and nearly parallel hole, this was done by gripping the part in a four jaw lathe chuck making sure to exert too much pressure on two opposing jaws to guarantee at least some distortion before the boring operation starts.
So first get rid of most of the metal with a big drill, then put the boring tool in the lathe with twice as much overhanging length as it actually needs.
The additional overhang should if I get it right, introduce some nice decorative chattermarks along the bore which will aid oil retention when the engine is running.

I measured the diameter of the bore periodically using my trusty Chinese digital vernier, and once the operation was completed to my satisfaction by being a few thou oversize I then removed the cylinder from the four jaw chuck and carefully measured the bore in different places with a telescopic gauge and micrometer.
Sure enough I had got it spot on for size with the bore being about 10 thou smaller where the tighter chuck jaws had been, and also it had just the right amount ot taper I was looking for, being about three thou smaller at the end where it had been gripped in the chuck.


Now to the second operation, and that is where the magic cylinder hone comes into play, actually I was a bit apprehensive about using it at first as I have heard that they are not all they are cracked up to be. With that in mind I wrote to the suppliers asking for their professional advice.
I need not have worried because I got a reply from them stating that there was no way that the cylinder hone was going to ruin my newly machined cylinder bore by making it either round or parallel. I would need to use a machine costing thousands of pounds, or make a lap if I wanted to do that.

So I held the cylinder hone in the chuck of my pillar drill and ran it at what to me seemed a reasonable speed.
The only thing I still did not have on my cylinder was a nice bell mouth, so I made sure that as I was running the hone in the bore that almost half the length of the stones was in mid air outside the bore, this allows the stones to rock a bit on the legs and produce a really nice bell mouthed effect.
It is almost impossible to measure this and you will just have to keep going until it looks right.

Once the bell mouth was finished, I decided to use the hone to put a surface finish on the rest of the bore without changing its shape.
Now it was at this point I was wondering what might happen, the worst case scenario would be if all my previous work was undone and it made the bore round and parallel, so with some trepidation I began randomly moving the hone up and down the bore whilst it was still spinning, you could almost see the stones bobbing in and out as they followed the existing taper and out of round shape.
Again I had no idea how long I should carry on doing this for but after a while I decided to stop the machine and have a look.

I was pleasantly surprised to find a really nice finish that sort of resembled a motorcycle one I had done years ago when a new piston was fitted.
Now the acid test was to take some final measurements and see if I had caused any damage with the hone.
So I repeated the telescopic gauge and micrometer measurements I had done previously, and lo and behold I could hardly detect any dimensional change at all.
So to sum up the cheap cylinder hone worked absolutely perfectly, it produced a nice finish that looked almost like a professionally honed cylinder, but did not remove any of the taper or out of roundness, and if used carefully it will give an acceptable bell mouth to the hole.



By the way I have now just taken my tongue out my cheek.

Now if I was making a conventional cylinder where being round and parallel is important, I might have used a rather different approach.
For a start it would not be done in a four jaw chuck, but would be bored out on the milling machine using a boring head, or more preferably fastened to the lathe cross slide using a between centres boring bar. We all know that having the tool spinning will give a far more accurate hole than having the work spinning around a stationary tool don't we.

As we saw on the honed cylinder earlier, there was no way the cylinder hone would remove ovality or taper in the bore, so I would probably make a lap to finish the cylinder to final size, I just might use the cylinder hone very carefully and only for a very short time to apply a fine oil retaining surface and no more.

Phil
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on May 04, 2013, 08:42:28 AM
Thanks for that Phil, very useful  :ThumbsUp:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 04, 2013, 10:22:08 AM
Phil,

I take your comments in the spirit in which they are meant.  It does rather suggest that I've done everything wrong!

I did consider using a between the centres boring bar but the difficulty of holding a round, thin walled, cast iron cylinder seemed troublesome compared with holding the solid stub end, distortion free,  in the chuck.  My decision would have been different with something like a loco cylinder or indeed, the table bearing on my Worden.

We shall have to agree to differ on the spring hone.  It's not perfect (I am not a perfectionist) but it appears, so far, to do an adequate job.

Anyway, no progress yesterday- instead, a trip to the GWR museum at Swindon:

(http://i104.photobucket.com/albums/m180/rod_sally/swindonws_zpsa656d871.jpg)

The brown thing in the corner is a tableau of a gurney on which an injured worker is being carted away.  Elsewhere in the museum are examples of artificial limbs that were made on site for the injured.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on May 04, 2013, 10:35:39 AM
Phil,

I take your comments in the spirit in which they are meant.  It does rather suggest that I've done everything wrong!

I did consider using a between the centres boring bar but the difficulty of holding a round, thin walled, cast iron cylinder seemed troublesome compared with holding the solid stub end, distortion free,  in the chuck.  My decision would have been different with something like a loco cylinder or indeed, the table bearing on my Worden.

We shall have to agree to differ on the spring hone.  It's not perfect (I am not a perfectionist) but it appears, so far, to do an adequate job.

Anyway, no progress yesterday- instead, a trip to the GWR museum at Swindon:

(http://i104.photobucket.com/albums/m180/rod_sally/swindonws_zpsa656d871.jpg)

The brown thing in the corner is a tableau of a gurney on which an injured worker is being carted away.  Elsewhere in the museum are examples of artificial limbs that were made on site for the injured.

cheers,

Rod

Rod.

There is no right or wrong, just different ways of achieving a result "you" are happy with.
When I make something, I do it in a way that I am happy with, but if you ask ten engineers how to do it you will probably get twenty different responses from them, all of which might work.

Keep cracking on, at least you are doing something.
A lot of critics probably never put into practice what they preach.

Phil
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 04, 2013, 11:07:30 AM

Rod.

There is no right or wrong, just different ways of achieving a result "you" are happy with.
When I make something, I do it in a way that I am happy with, but if you ask ten engineers how to do it you will probably get twenty different responses from them, all of which might work.

Keep cracking on, at least you are doing something.
A lot of critics probably never put into practice what they preach.

Phil

We're on exactly the same wavelength - your, and anybody else's, comments are very welcome

Rod  :)
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on May 04, 2013, 11:57:40 AM
Thanks for that Phil, very useful  :ThumbsUp:

Jo
Yes extremely useful Phil!....glad you did that...I love data!

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on May 04, 2013, 12:05:02 PM
Phil,

I take your comments in the spirit in which they are meant.  It does rather suggest that I've done everything wrong!

I did consider using a between the centres boring bar but the difficulty of holding a round, thin walled, cast iron cylinder seemed troublesome compared with holding the solid stub end, distortion free,  in the chuck.  My decision would have been different with something like a loco cylinder or indeed, the table bearing on my Worden.

We shall have to agree to differ on the spring hone.  It's not perfect (I am not a perfectionist) but it appears, so far, to do an adequate job.

Anyway, no progress yesterday- instead, a trip to the GWR museum at Swindon:

(http://i104.photobucket.com/albums/m180/rod_sally/swindonws_zpsa656d871.jpg)

The brown thing in the corner is a tableau of a gurney on which an injured worker is being carted away.  Elsewhere in the museum are examples of artificial limbs that were made on site for the injured.

cheers,

Rod

Hey Tangler,

I'm about to go visit a WORKING shop like that all belted up.....save a couple of extra arms for me!...... :lolb:

Promise I'll take pictures!

Now....looking at this thread...I would like to say ...well done.    THAT is what we want.
A difference of opinion, a discussion of the aspects of the problem....friendly respectful debate...we can still go get a pint when we're done.

Perfect!
THAT makes a great forum.   Thankyou for posting, and more importantly participating in this!  WE don't make the forum great...the membership does!
 :praise2:

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on May 04, 2013, 12:31:40 PM
Rod,

Just to go back to your boring bit.

If at all possible, it is always better if you can bore with the whole length of the bore outside the chuck jaws. In other words, have your material slightly longer, with the chucking piece only within the jaws, bore your depth or slightly longer, then part it off.

Under certain circumstances, if the bored part is gripped in the chuck, even partially, when the chuck is released, you could end up with a slightly triangular or square bore (depending how many jaws are used) where it has been sitting inside the jaws.  This can happen, mainly on sleeves, where the walls are deflected inwards by jaw pressure while being held during the boring process.

We have enough to contend with by tool deflection, having to true up a bore afterwards can make things even more difficult.


John
Title: Re: ETW's Wyvern Gas Engine
Post by: Ian S C on May 04, 2013, 01:30:37 PM
John, I found how to make triangular bushes early in my time on the lathe, while making new bushes for the forks on a motor bike.  Made the two bushes out of one bit of bronze, drilled it through, bored them to size, parted them.  The front one that was out of the chuck, spot on, the second one, Oh dear /_\, well sort of, luck has it I had another bit of bronze.  Ian S C
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 04, 2013, 02:24:56 PM
John,

Agreed.  Here's the stub end of the cylinder liner still in the 4 Jaw SC chuck.  I tend to leave things set up for the last operation until I need the kit for something else - you never know when you might need to go back.

(http://i104.photobucket.com/albums/m180/rod_sally/cylinderstubend_zpsf96c0e4f.jpg)

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Bogstandard on May 08, 2013, 09:34:53 AM
Ian,

There are times that you have to bore with the part in the jaws. I usually get away with it by only just nipping the jaws and taking very fine boring cuts. It doesn't matter too much about the initial drilling, as boring straightens things out, just that when drilling, take it easy and do it in fine stages, otherwise the part might start to rotate in the jaws, or else, if you have enough material left to bore out, tighten up the jaws for drilling, then slacken them off for boring.

Rod,

Spot on :NotWorthy: :praise2: :NotWorthy:


John

Title: Re: ETW's Wyvern Gas Engine
Post by: Ian S C on May 08, 2013, 12:37:07 PM
Your right there John, I was a bit green, and did not know about that sort of thing, I was/am serving a self tutored apprentiship in a number of branches of engineering, 20yrs on, must be getting nearer to some sort of qualification or something.   Ian S C
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 09, 2013, 10:59:12 AM
The weather's turned manky again - here's a bit more progress, this time on the crankshaft:
 Starting with two discs of mild steel and a length of Precision Ground Mild Steel

(http://i104.photobucket.com/albums/m180/rod_sally/crank1_zps07733dc9.jpg)

First disc was mounted in the 3 jaw SC and faced, then turned around, bedded down and reduced to the final 3/8" thickness

(http://i104.photobucket.com/albums/m180/rod_sally/crank2_zps220b5030.jpg)

then drilled, bored

(http://i104.photobucket.com/albums/m180/rod_sally/crank3_zps7b61d54a.jpg)

and finally reamed to 1/2".  In my experience 1/2" PGMS in a 1/2" reamed hole gives a sliding fit with adequate clearance for lubrication or Loctite as appropriate.

(http://i104.photobucket.com/albums/m180/rod_sally/crank4_zps8893d4f5.jpg)

The operation was repeated for the second crank disc.  I took the opportunity to scribe a couple of lines at right angles using the HDA and a screwcutting tool on its side set exactly at centre height.

(http://i104.photobucket.com/albums/m180/rod_sally/crank5_zps6fafd7dc.jpg)

The plan now was to bolt the two webs together through the waste area, keeping alignment using a stub of PGMS (actually the centre from my dividing head tailstock)

(http://i104.photobucket.com/albums/m180/rod_sally/crank6_zps8e49848f.jpg)

The holes were deeply countersunk for 6mm screws

(http://i104.photobucket.com/albums/m180/rod_sally/crank7_zps27c9d66c.jpg)

and one surface marked out and centre popped for the crank pin

(http://i104.photobucket.com/albums/m180/rod_sally/crank8_zpsc0c6ab6f.jpg)

A bit of old school machining now using the facelplate and a lathe centre to pick up the crank pin centre

(http://i104.photobucket.com/albums/m180/rod_sally/crank91_zps6a7bfb71.jpg)

With the faceplate roughly balanced the crank pin hole was drilled, turned and reamed as before.

(http://i104.photobucket.com/albums/m180/rod_sally/crank92_zps5b162500.jpg)

I next made a 1/2" stub arbour.  The biggest nuts I've got are 7/16" BSW so I screwcut a thread of this size (I don't have a die and probably wouldn't be able to turn it anyway).  The discs were mounted on the arbour and the the OD cleaned up.  It is suggested that the engine is under balanced so I have left the crank webs over sized

(http://i104.photobucket.com/albums/m180/rod_sally/crank94_zpsee0d7b10.jpg)

The chamfer on the outsides of the webs was turned by setting the topslide over to 30 degrees, repeated for the other face.

(http://i104.photobucket.com/albums/m180/rod_sally/crank95_zps9c79f580.jpg)

So. here we have a pair of crank webs ready to have the waste areas cut away

(http://i104.photobucket.com/albums/m180/rod_sally/crank96_zps14dfca66.jpg)

How to do the next bit, that's the question.  I can use the stub mandrel through the centre hole to keep the 2 webs together with a length of PGMS through the crankpin hole to maintain alignement.  The total thickness is 3/4".  I could just hacksaw them out by hand, tidying up with an endmill.  Or chain drill and saw (using my last, precious abrafile blade).  I could use a slitting saw in the mill but that is a long and tedious process if the saw isn't to go blunt halfway through - possibly I should do some experimentation with some lumps of steel.  This needs thinking about  :headscratch:





Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on May 09, 2013, 11:03:40 AM
Make the most of both holes to keep them together then hacksawing by hand and finishing using an end mill would be my favourite of those options  ;).

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 09, 2013, 12:09:57 PM
Jo,

You know that's not the answer I want  >:(, even if it is the best option :-\  Perhaps I should just go and do it - I probably (definitely) need the exercise
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 09, 2013, 12:59:44 PM
OK, I just needed to be told.  A nice new 18tpi blade and a dab of cutting oil.  About 4 minutes per cut.  No sweat (well not much).  And I managed to stay the correct side of the lines!

(http://i104.photobucket.com/albums/m180/rod_sally/crank97_zps143666dd.jpg)

 ;D
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on May 09, 2013, 01:06:00 PM
 :ThumbsUp:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 09, 2013, 08:33:53 PM
OK, having done my exercise for the month, the webs were tided up in the milling machine.  When I took the stub arbour out of the chuck I turned it around and mounted it in a 1/2" Myford collet to turn the other end to exactly 1/2".  I was then able to mount the arbour and webs in the dividing head, which has a 2 MT and Myford nose

(http://i104.photobucket.com/albums/m180/rod_sally/crank21_zps45523105.jpg)

I also tidied up the corners

(http://i104.photobucket.com/albums/m180/rod_sally/crank22_zpsa6d4500b.jpg)

here are the webs off the mill

(http://i104.photobucket.com/albums/m180/rod_sally/crank23_zps8ee2bb94.jpg)

A bit of draw filing with a No 6 cut file got rid of the end mill traces and dulled the arrises

(http://i104.photobucket.com/albums/m180/rod_sally/crank24_zps9e207c22.jpg)

Mounted in a Myford collet, the 1/2" main shaft is reduced to 3/8" and has a 3/8" 26 thread at each end.  I chamfered the ends with the hand graver

(http://i104.photobucket.com/albums/m180/rod_sally/crank25_zpsda265bd8.jpg)

Then screwcut the threads, finishing off with a die

(http://i104.photobucket.com/albums/m180/rod_sally/crank26_zps84afc417.jpg)

I de-greased everything with my useful litre of Acetone, bought in a French supermarket (Lord knows where you would buy such a thing in the UK - Even Waitrose doesn't stock it ;) ).  It was then assembled with Loctite.  I'll leave it for a couple of days before pinning and sawing out the central shaft

(http://i104.photobucket.com/albums/m180/rod_sally/crank27_zps12a724f1.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on May 09, 2013, 08:43:37 PM
It looks like it was well worth the effort  :ThumbsUp:

Acetone is nail varnish remover. ;)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Bluechip on May 09, 2013, 08:49:40 PM
You can get acetone at CPC. Far from cheap though ...  :rant:

http://cpc.farnell.com/_/ace500/acetone-500ml/dp/SA02608

I used to burst into tears when it was 15 bob a gallon  :old:

Dave BC
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 09, 2013, 08:56:34 PM
OK (big sigh) I have a confession to make :o  I try to play the classical guitar and for that I need nails on my right hand.  This doesn't mix terribly well with lathe work so I have spent a considerable amount of time staring at the nail products in the supermarket and trying out various things, including (transparent) nail varnish to try and stop cracks from propogating.  I therefore do have my own nail varnish remover but it says it contains conditioning agents, which presumably put the oils back in.  My right thumb nail is down to the quick at the moment.  My solution these days is to stick on an artificial nail (actually a toe nail - I didn't know you could get such things) with a piece of elastoplast when I play.  Too much information?

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on May 09, 2013, 08:59:57 PM
Me too!

 :ThumbsUp:

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Naffsharpe on May 09, 2013, 09:14:23 PM
Rod ,Try using a ciggy paper and nail varnish or for longer lasting pickers nails, sand them to give a key and use Araldite epoxy to coat them. I use both depending on how long I expect to be "damaging" them.
I do get a few strange looks if all my lady has to spare is bright/sparkly varnish!

 Nathan.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 16, 2013, 03:33:16 PM
Hello again,

We've been down to Devon for a few (wet & windy) days.  Managed to see the 1:1 model of Lyd, a Manning Wardle locomotive that has been reproduced for the Ffestiniog Railway but was visiting "home", the short remaining length of the Lynton & Barnstaple Railway.

(http://i104.photobucket.com/albums/m180/rod_sally/lyd_zpse73b9e71.jpg)

The Loctite holding the crankshaft together has had a few days to cure so I've cut out the central shaft with a hacksaw and tidied up using a mill.

(http://i104.photobucket.com/albums/m180/rod_sally/crank98_zps7da2ccae.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/crank99_zpscf759637.jpg)

I've been having a think about pinning.  It seems to me that if you pin the crankshaft then you don't need the glue, a light press fit would do.  So if you don't trust the glue why use it?  In the quest for knowledge I've decided to experiment and leave the pins out.  If the bond fails then I can always go back and pin afterwards.  We'll see.

Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on May 16, 2013, 04:51:22 PM
The glue (loctite) holds things in place for drilling and pinning. You might well get away without pinning but give some thought to what might happen if the glue does slip at some point...what else might get massed up? Pinning is cheap insurance. The crankshaft looks outstanding BTW!!!

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: mklotz on May 16, 2013, 05:42:19 PM
Loctite doesn't like heat.  I Loctited the crank on my Poppin and, during a long run, the crank "melted".  It's pinned now.  As Bill says, use it to keep things in place while you mount pins but don't depend on it unless you have a water-cooled crank.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 16, 2013, 09:08:07 PM
Bill and Marv, thanks for the cautions:  I can't think of any catastrophes if the bond should slip - the only real issue is that the timing will go out but we're not going to get the piston crashing into the valves on this old slugger.  With a water cooled cylinder I can't see this massive crankshaft getting warm.

I've been trying to follow full size practice of only machining the casting where it needs it, so I need to spot face the seats for the main bearings.  Inspired by Jo with the R&B, I made a rose cutter by crudely filing up a piece of 3/4" mild steel.  The aim was to case harden this but I thought I'd try it soft first on the friable and buttery casting.

(http://i104.photobucket.com/albums/m180/rod_sally/mb1_zps034c87d2.jpg)

The rose bit can be nipped up onto a 1/2" shank that has 5/8" collars which are the same diameter as the main bearing seats

(http://i104.photobucket.com/albums/m180/rod_sally/mb2_zps395df9f3.jpg)

The whole contraption was held in a pistol drill.  The spot faces were easily cut into the casting with the un-hardened rose

(http://i104.photobucket.com/albums/m180/rod_sally/mb3_zps106d909e.jpg)

and, of course, the drill has a soft start and is reversible

(http://i104.photobucket.com/albums/m180/rod_sally/mb4_zps4034e2f8.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/MB9_zps69e21c88.jpg)

The main bearings themselves are a simple turning job.  Drilled , bored and reamed through 1/2" and the middle recessed with the parting tool to fit in the seats

(http://i104.photobucket.com/albums/m180/rod_sally/mb5_zps4e04d8ff.jpg)

and then parted off to slightly over length

(http://i104.photobucket.com/albums/m180/rod_sally/mb6_zps05ae11a8.jpg)

I had to do a bit of fitting on the lengths to get everything to sit in the right place

(http://i104.photobucket.com/albums/m180/rod_sally/mb7_zps6cbe47f6.jpg)

The caps snug down nicely and the crankshaft turns freely without shake - or at least it would do but the the cast in slot of the base is slightly too narrow so that will have to be opened a tad

(http://i104.photobucket.com/albums/m180/rod_sally/mb8_zps8a9093ca.jpg)

Looking at that picture though I can see a problem  :o  A vertical hole from the oiler seat  is not going anywhere near the shaft. 
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on May 16, 2013, 09:21:16 PM
Nice work with the rose bit  :ThumbsUp:

Looking at that picture though I can see a problem  :o  A vertical hole from the oiler seat  is not going anywhere near the shaft.

No problem: drill and tap for the oiler to be vertical and then drill the oil hole from the back at an angle  ;). Just remember to make sure the oil hole in the bearings also lines up with the feed hole.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 16, 2013, 09:49:28 PM
Ta Jo, panic over   :ThumbsUp:.  I guess it might be worth making the feed through the bearing a slot rather than a hole.

cheers,
Rod
Title: ETW's Wyvern Gas Engine
Post by: NickG on May 16, 2013, 09:58:44 PM
Rod, that is (I think) the point of a casting in this case -  it should only be machined where it needs to be. I think because of the poor quality of a lot of
Castings people start dressing them then machining them and before they know it they have machined it all over to make it look nice so defeating the purpose some what!

I didn't pin mine either, all be it it was
Only on a poppin engine with a small fraction of the power this beast will have! is drilling afterwards not more likely to loosen or weaken the bond though? Loctite is really strong stuff if applied correctly with correct clearances however as Marv said the bond can be broken with heat, Some types can withstand a fair amount of heat though, certainly higher than you'd expect a crankshaft to get. Great work.
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on May 16, 2013, 11:42:50 PM
Rod

You might want to consider putting an oil groove on the inside of the bearing to allow the oil to spread along the length, I put them in mine but stop short of it breaking out at the sides to keep the oil in.

Phil

Ta Jo, panic over   :ThumbsUp:.  I guess it might be worth making the feed through the bearing a slot rather than a hole.

cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 19, 2013, 03:19:43 PM
Phil,  Thanks, I''ll do that.

I need to do a couple of tweaks on the bed plate casting.  The cylinder jacket interferes with the bed plate hold down bolt lugs so I need to reduce them.  This will have the added advantage that I can move them sideways a little to help get the hold down nuts away from the jacket nuts on assembly.  As mentioned above, I also need to open out the gap in the bedplate a little to clear the crank webs.

The bedplate was set up square on the milling table.

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak1_zpse718eb5a.jpg)

I used my longest endmill to remove the bosses completely

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak2_zpsb6057961.jpg)

I didn't want to touch the already machined seat for the cylinder jacket so left a slight ridge

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak3_zps19fdba21.jpg)

which I removed with a triangular file

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak4_zps6b4035c1.jpg)

I then attacked the base gap with the endmill, note the spacers under the bedplate

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak5_zps198ba9e4.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak6_zps61d45f18.jpg)

Here are all the bits so far

(http://i104.photobucket.com/albums/m180/rod_sally/bptweak7_zpsb267dda0.jpg)

Things would have been easier if I'd made the base of the bedplate thinner.  The cylinder would be slightly higher up the casting, thus getting rid of the interference problem and the bearing caps would have sat further along the bearing lugs, thus bringing the oiler centres nearer the centre of the bearing.  In retrospect, It would have been worthwhile to go to the trouble of mounting the bedplate up side down and milling that surface rather than filing
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 27, 2013, 05:31:52 PM
The next job is the con-rod.  Just to make it clearer what I'm trying to do, here's a picture of the (nearly) finished item

(http://i104.photobucket.com/albums/m180/rod_sally/cs1_zps320247aa.jpg)

ETW describes a marine type big end - a split rectangular block of bronze bolted to a thin flange on the end of the con-rod.  I don't have a lump of bearing bronze but I do have some 3/4 round so I've modded the design to use that.

Two lengths of 1/2" square and 1/2 x 3/4" mild steel were bolted together to make the split bearing housing and then drilled, bored and reamed

(http://i104.photobucket.com/albums/m180/rod_sally/cs2_zpsbe4afcfb.jpg)

Another deviation from ETW: he brazes the big end on to the con-rod but as I'm undergoing a Loctite fetish at the moment I decide to screw (1/4" x 40) the parts together with high strength retainer.  So the big end was re-held in the 4 jaw, drilled and tapped

(http://i104.photobucket.com/albums/m180/rod_sally/cs31_zps5d8fec25.jpg)

Although I have a VFD on the Myford I find it much more comfortable to use the mandrel handle for this sort of job

(http://i104.photobucket.com/albums/m180/rod_sally/cs3_zpsa0606681.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cs4_zps86665667.jpg)

The little end is in the form of a ball and the shaft is tapered.  I turned the final diameter before the ball with the parting tool

(http://i104.photobucket.com/albums/m180/rod_sally/cs5_zps4f7b6f77.jpg)

I use my dividing head with the division mechanism disengaged for ball turning.  Using the keys, the head can be mounted on the cross slide exactly at centre height and square or parallel to the axis

(http://i104.photobucket.com/albums/m180/rod_sally/cs51_zpsa09ac608.jpg)

The tool holder is made from an old Flexispeed topslide mounted on a 2MT arbour (sorry about the photo, I must have kicked the tripod)

(http://i104.photobucket.com/albums/m180/rod_sally/cs52_zpsce9e4680.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cs53_zps926d382e.jpg)

Once I was happy with the ball the shaft was turned end for end and the thread cut with a die

(http://i104.photobucket.com/albums/m180/rod_sally/cs54_zps1e29807b.jpg)

The taper works out at just under 1 degree.  In order to turn the topslide handle I had to have an uncomfortable amount of over hang on the tool but I avoided taking large cuts and it worked out OK.  I held the shaft in the 3 jaw to start with to rough out the taper.  There is insufficient to travel on the topslide to cover the whole length but as the taper is largely aesthetic I'm not to bothered about this

(http://i104.photobucket.com/albums/m180/rod_sally/cs55_zps3274a619.jpg)

I transferred the shaft to a collet for finishing.

(http://i104.photobucket.com/albums/m180/rod_sally/cs56_zps6a196694.jpg)

 Tool marks were removed with a dead smooth file.

(http://i104.photobucket.com/albums/m180/rod_sally/cs57_zps4959360f.jpg)



Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on May 27, 2013, 05:36:59 PM
That conrod looks good.

Nice use of that dividing head  :ThumbsUp: That was really thinking out of the box  ;)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 27, 2013, 05:42:56 PM
Jo,

Thank you.  I made a Quorn once.  There were an awful lot of balls.  It gets you thinking.

cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 27, 2013, 07:37:06 PM
The big end has been screwed and Loctited onto the shaft.  I now need to make the "brasses" for the con-rod out of Colphos.  The big end brasses are split so I milled a 3/4" diam. down to half (that's a pile of expensive swarf). 

(http://i104.photobucket.com/albums/m180/rod_sally/brass1_zps7ebfa8af.jpg)

The 2 halves were sawn out prior to joining

(http://i104.photobucket.com/albums/m180/rod_sally/brass2_zps074a23f7.jpg)

I used (of course) Loctite.  Slightly concerned about this because the act of drilling and boring the bearing will tend to force the halves apart and adhesives do not generally have good peel strength but I reckoned that holding the assembly in the 3 jaw chuck would stop that.

(http://i104.photobucket.com/albums/m180/rod_sally/brass3_zpsc0c6e451.jpg)

I was wrong :'(

(http://i104.photobucket.com/albums/m180/rod_sally/brass4_zps7d8a616e.jpg)

It looks like the bond to the metal has failed, not that the Loctite itself has ruptured.  Oh well, back to old school soft solder

(http://i104.photobucket.com/albums/m180/rod_sally/brass5_zps832cbd79.jpg)

After facing, drilling, boring and reaming in the 3 jaw I was able to re-use the mandrel I'd made for the crank shaft

(http://i104.photobucket.com/albums/m180/rod_sally/brass6_zps6cead69d.jpg)

I used the parting tool to turn the recess to fit the big end

(http://i104.photobucket.com/albums/m180/rod_sally/brass7_zpsafb02073.jpg)

warming the bearing up soon melted the solder and split the two parts

(http://i104.photobucket.com/albums/m180/rod_sally/brass8_zps06148633.jpg)

The hole through the little end bearing must be parallel with the big end so I made a stub to mount on the mill table

(http://i104.photobucket.com/albums/m180/rod_sally/brass91_zps4fe192e8.jpg)

The big end was packed up with a couple of ball races to bring the shaft up to a height where I could hold the little end in the vice.  The diameter of the hole through the big end is not actually critical as I will turn the bearing brass to fit.  I'm going to press this in so I left reaming the gudgeon pin hole until after assembly.  I decided to use a slot drill to make the hole in the little end as this was most convenient.

(http://i104.photobucket.com/albums/m180/rod_sally/brass92_zps8994ce58.jpg)

It may have been convenient to use the slot drill but the hole turned out to be bell mouthed :o.  Fortunately the hole is 5/16"( 0.313") so I was able to put an 8mm (0.315") reamer through which brought things back on track.

(http://i104.photobucket.com/albums/m180/rod_sally/brass93_zps627f88a9.jpg)

I turned the bearing OD to 0.316" and pressed it in using the bench vice, then trimmed up the sides and reamed the hole 1/4"

(http://i104.photobucket.com/albums/m180/rod_sally/brass94_zpsc0e37694.jpg)

Well, I just about managed to keep things together.  I haven't needed to remake anything...yet!





Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on May 27, 2013, 08:30:46 PM
Good progress Rod and nice parts.  Still following along.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: Bearcar1 on May 27, 2013, 09:24:16 PM
What an elegant way to make a connecting rod. I have to admit, I am having a bad case of lathe envy. Beautiful machine you have to work with, Rod. So far, it seems that you are able to work around the nigglies as they arise, I hope that continues for you. Looking forward to your next installment.  :ThumbsUp:


BC1
Jim
Title: ETW's Wyvern Gas Engine
Post by: ths on May 27, 2013, 11:51:46 PM
That is a nice conrod, and the ball turner is a great out of the square thought. Are dead smooth files easy to locate? I assume that they just take a very fine cut.

Cheers, Hugh.
Title: Re: ETW's Wyvern Gas Engine
Post by: zeeprogrammer on May 28, 2013, 11:03:38 AM
Nice looking conrod.

I've seen a few posts now that use the soldering technique to make the split bearing. After remelting to split it, are there any additional operations done to the joins? Filing, just pickling, or such? Any concern that the parts won't mate exactly the same? Thanks.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on May 28, 2013, 11:29:39 AM
Hi, Jim, Hugh , Carl,

I was very lucky to get the lathe, as is often the way with these things at someone else's misfortune.  My old neighbour was an (old school) professional engineer who was gearing up his workshop for retirement.  Sadly, Reg smoked himself to death and didn't last too long after his 65th birthday.  When he died his widow was keen for me to take over the lathe.  The lathe was about 10 years old but hardly used.  I think I gave her a fair market price but there was an enormous amount of other stuff that she wanted me to take - effectively a complete workshop.

The dead smooth file is a Swiss Grobet No. 6 cut.  I find it really useful for all sorts of finishing tasks.  I've also got a no.4 cut.  They are not easy to find and are very expensive in the UK these days.  They seem a bit cheaper in the US such as http://www.ottofrei.com/Grobet-Swiss-Vallorbe-Files-Hand-6-Inch.html (http://www.ottofrei.com/Grobet-Swiss-Vallorbe-Files-Hand-6-Inch.html).  I don't know about Oz

That's the first time I've tried the soldering technique for a split bearing.  When I dis-assembled I wiped the still liquid solder off on  piece of paper and gave the surface a quick rub on a file.  Seemed very straightforward.

Thanks for taking an interest,
cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on June 22, 2013, 07:05:18 PM
Rod,

How is the Wyvern coming on?   :???:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 23, 2013, 10:28:37 PM
Hi Jo,

No progress for the last 3 weeks.  Holidays!  Back to normal tomorrow.

Thought the group might be interested in this, just sitting on a wall outside someone's house in the NW corner of the Isle of Lewis:

(http://i104.photobucket.com/albums/m180/rod_sally/gasengine_zpsac77af67.jpg)

Anybody recognise it?

Also been down to the West Country and dropped in at Crofton Pumping Engines on the way back.  I thought this Gardiner steam engine looked like quite a nice ( relatively) simple prototype to copy- I've been enthused by Jo's cotters.  The flywheel is built up.

(http://i104.photobucket.com/albums/m180/rod_sally/croft1_zpsacad7e0c.jpg)

I should have some progress on the Wyvern to post in the next couple of days.

Looking forward to seeing the Crosskill at Guildford

cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on June 24, 2013, 08:51:32 AM

Also been down to the West Country and dropped in at Crofton Pumping Engines on the way back.  ...

Looking forward to seeing the Crosskill at Guildford

The Crofton engines :Love:

Looking forward to seeing you Rod (P.S. photographs are only allowed of the engines  ;), any one who wants to see the live entertainment   :disappointed: has to come along )

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on June 24, 2013, 10:44:49 AM
Rod looks like a Amanco/Associated "Hired Man"

I'll just make sure I focus on whats behind the engines when I take pictures of them :mischief:
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on June 24, 2013, 11:35:31 AM
"Amanco Hired Man":

(http://www.stationaryengine.org/amanco_woolpit_2003.jpg)

 :noidea:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on June 24, 2013, 12:15:04 PM
Rod, looking forward to seeing more on the Wyvern as well. Meanwhile it looks like you have had an enjoyable few weeks :)

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 24, 2013, 01:23:18 PM
Certainly looks like a Hired Man.  Thanks Jason and for the pic Jo.  On the way up to Scotland we visited Quarry bank Mill.  They've got a little six column beam engine there that looks very much like the prototype for Tubal Cain's Lady Stephanie.  Also, the Gardiner above is very similar to his Georgina.

We did have a great time and were very lucky with the weather.

(http://i104.photobucket.com/albums/m180/rod_sally/calanish_zpsf7c7d55a.jpg)

Callanish Standing Stones
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 26, 2013, 08:51:30 PM
One of the the (supposedly!) simple jobs I've been putting off is to make a drilling jig for the studs to fasten the cylinder jacket to the bed plate.  This can be a simple plate with a hole in to match the cylinder, which will act as a locator when drilling either the jacket or the bed plate.  The bed plate needs drillings for a 4BA tap and the jacket has equivalent clearance holes.  I found a suitable piece of plate to act as the jig - one of the spare cast ally mounting fixtures that came with my DRO kit.  I mounted this in the 4 jaw and bored a hole for a snug fit on the cylinder.  I decide to use my milling spindle to drill the holes according to the drawing - on a 1 3/16 radius pitch circle, 7/8" either side of the vertical centre line.  A bit of trigonometry calculated the angles necessary so that I could use the HDA to rotate the job to the required position.

(http://i104.photobucket.com/albums/m180/rod_sally/jig2_zps2cdde62c.jpg)

The milling spindle is mounted on a base at  centre height which fits into the hole for the top slide. 

(http://i104.photobucket.com/albums/m180/rod_sally/jig1_zps1e535f75.jpg)

The accuracy of this job is not micron critical so I just used a centre in the head stock to line up the drill at centre and then moved out to the required radius on the cross slide.

(http://i104.photobucket.com/albums/m180/rod_sally/jig3_zpsef1c9f9a.jpg)

I was beginning to have a bad feeling about this because the cylinder jacket casting flange is not very square and the holes looked like they would be too close to the cylinder jacket to allow a nut to turn.

(http://i104.photobucket.com/albums/m180/rod_sally/jig5_zpsb69b953e.jpg)

Sticking to the principle of only machining the castings where necessary may not end up with a pretty end product.  Anyway, I just spotted the holes with the centre drill. Using the cylinder as the locator and drawing around the flange shows the problem.  So, having gone to all that trouble I just put some new centre dots where I thought the holes ought to to go (where I've placed the nuts) and drilled them.

(http://i104.photobucket.com/albums/m180/rod_sally/jig4_zps5f8ebd45.jpg)

Drilling the blind stud holes in the bed plate wasn't that straight forward either.  There isn't enough headroom on my drill to get the up ended plate under the drill.  I bolted it to an angle plate and used a DTI to level it.

(http://i104.photobucket.com/albums/m180/rod_sally/jig6_zps4d41e7ef.jpg)

I then had to have the assembly hanging off the edge of the drill table but it worked OK.

(http://i104.photobucket.com/albums/m180/rod_sally/jig7_zps7bff2253.jpg)

The holes were tapped on the pillar tool and some temporary studs inserted.  It all bolted together after I'd opened up the clearance holes in the cylinder jacket by another 0.1mm

(http://i104.photobucket.com/albums/m180/rod_sally/jig8_zps5ee2b396.jpg)

Just at the moment I think my next model is going to be all fabricated!

 
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on June 26, 2013, 08:54:36 PM
I like that drive Tangler!

Nice work on the engine too!

Dave
Title: ETW's Wyvern Gas Engine
Post by: NickG on June 26, 2013, 11:13:02 PM
Yeah good work there, it looks good assembled and there isn't that much of a miss match but it must be frustrating that you had to deviate from the drawing with the bolt hole pattern! The more I see people work with castings the more I am put off by them!
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on June 27, 2013, 07:13:20 AM
...
Just at the moment I think my next model is going to be all fabricated!

 :lolb: And Fabrication has its challenges. You are doing well Rod  :ThumbsUp:

Nick: Yes there are good sets of castings, many ok and sadly some really awful ones. Looking at Rod's problem I would have said that was a drawing fault that should have been corrected years ago.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 27, 2013, 08:50:20 PM
Well, I guess it's these little challenges that make it interesting  :thinking:

So, on to the next one - the cylinder head.  There's a chucking piece/ sprue on this so I thought the first job was to turn a flat on the base .

(http://i104.photobucket.com/albums/m180/rod_sally/cy11_zps05410847.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cy12_zps0855c133.jpg)

I then bedded the flat in the 4 jaw and adjusted until the chucking piece was running as true as possible before turning it cylindrical.

(http://i104.photobucket.com/albums/m180/rod_sally/cy13_zps8bbd029b.jpg)

I chose to hold this in a collet so that I could move it about and replace as necessary.  The head needs a recess for the flange of the cylinder to fit into which makes the head/cylinder joint gas tight

(http://i104.photobucket.com/albums/m180/rod_sally/cy14_zpsc78929e2.jpg)

But the cylinder head also needs to be in good contact with the cylinder jacket so that there is a good thermal transfer to keep the head as cool as possible.  So quite a bit of shaving and trying until a smear of blue showed that everything was snug.

(http://i104.photobucket.com/albums/m180/rod_sally/cy15_zps805523e4.jpg)

A taper was then turned to make the combustion space.  You can see that there is some gas porosity in the casting but I don't think this will be a problem

(http://i104.photobucket.com/albums/m180/rod_sally/cy16_zps09d43dd7.jpg)

The design shows an inserted valve seat/guide for the inlet valve which has a flange seat on the cylinder head.  The exhaust valve is shown as seating  directly in the cylinder head - fine for a cast iron head but not, I think acceptable in (porous) cast ally.  One of the seats need to be removable to get the valves in.  There isn't much of a flange seat cast into the head on the exhaust side so I need to think about a design.  I'll root around the other Wyvern builds on the net for inspiration - michaelr managed it.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 13, 2013, 12:14:12 AM
Hello again, I'm afraid I've been a bit distracted by Murray mania and the good weather here in the UK - I need to see a bit of sunshine occasionaly lest my transformation to Gollum becomes complete.  Anyway, a bit more progress on the cylinder head.  The inlet and exhaust holes for the valve housings need  to be bored to intersect the compression space and then the inlet and exhaust ports are drilled to intersect the valve housing holes.  The chucking piece on the cylinder head is true with the cylinder axis so this can be transferred to a collet in the dividing head mounted on the mill for drilling and boring.  Here is my quick and dirty method for centering the dividing head.  The two bars are 1/2" precision ground MS milled to exactly half depth and held in collets - ER25 in the DH and Myford patent in the mill.  It's good enough where extreme accuracy isn't required.  Direct indexing was used to rotate the cylinder head in 90 degree steps for each face to be dealt with.

(http://i104.photobucket.com/albums/m180/rod_sally/vs4_zps84b67104.jpg)

With the centre found and using the cylinder face as a datum the various holes can be faced, drilled, counterbored and bored as appropriate

(http://i104.photobucket.com/albums/m180/rod_sally/vs41_zpsa3b26e7e.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/vs5_zpsd9f0cc21.jpg)

The depth of the intersecting holes needs careful monitoring

(http://i104.photobucket.com/albums/m180/rod_sally/vs6_zpsf0351133.jpg)

The inlet and outlet ports were drilled but the valve housings were bored to give a good fit with the inserts

(http://i104.photobucket.com/albums/m180/rod_sally/vs61_zpsae778d44.jpg)

The seat end of the valve housing isn't bored through so as to provide to provide a gas tight seal

(http://i104.photobucket.com/albums/m180/rod_sally/vs71_zps518c9d28.jpg)

Next, the valve housings...
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 13, 2013, 01:16:51 PM
This is the casting as provided for the inlet valve housing

(http://i104.photobucket.com/albums/m180/rod_sally/vs1_zps32ede44c.jpg)

registration of the 2 halves isn't great but I can get the part out of it

(http://i104.photobucket.com/albums/m180/rod_sally/vs2_zpsb61b94d4.jpg)

Oh, and in amongst the bits I found the casting for the marine type bearing for the big end bearing.  Doh! :-[

(http://i104.photobucket.com/albums/m180/rod_sally/vs21_zps505589b5.jpg)

The casting was mounted as true as possible in the 4 jaw and then turned up so that I could then mount it in collets so that the job can be turned end for end. 

(http://i104.photobucket.com/albums/m180/rod_sally/vs3_zps281c2e11.jpg)

The housing was drilled and reamed 1/8" for the valve spindle and then counter-bored from both ends using a 5/16" slot drill.

(http://i104.photobucket.com/albums/m180/rod_sally/vs31_zpsa1fcc016.jpg)

I made up a filing jig from 3/32" steel to shape the flange

(http://i104.photobucket.com/albums/m180/rod_sally/DSC_1387JPG20130713_0001_zps363ce8e1.jpg)


As mentioned, the valve housing needs to seal in the bottom of its pocket so I used feeler gauges to determine how much need to be removed so that the flange would also seal.

(http://i104.photobucket.com/albums/m180/rod_sally/vs72_zps27ca5019.jpg)

I've left a gap of 1 thou.

(http://i104.photobucket.com/albums/m180/rod_sally/vs8_zps010723e8.jpg)

ETW's design  tapers the external housing for aesthetic effect but I'll leave that until I'm sure I don't want to return it to the collet - I still need to turn the valve seat but I'll do that when I turn the valves

Again, as mentioned, the exhaust valve in the design seats directly in a cast iron head.  For this ally head I need to make an exhaust bronze housing similar to the inlet one, constrained by a) there isn't room on the head casting for a similar flange and b) the biggest piece of bronze I've got is 3/4" diameter.  I decided on a square flange.

(http://i104.photobucket.com/albums/m180/rod_sally/vs7_zpsd7ad8192.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/DSC_1381JPG20130712_0004_zps2e3de362.jpg)

I drilled the mounting holes for the flange using the milling spindle and the HDA

(http://i104.photobucket.com/albums/m180/rod_sally/vs96_zps1dbed204.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/vs97_zps2d4dd53f.jpg)

There's just room to turn a 1-size-smaller 8Ba nut

(http://i104.photobucket.com/albums/m180/rod_sally/vs9_zpsb9d9db9e.jpg)

I'm thinking I might use a 6BA thread on the stud in the head casting, reduced to 8BA through the flange mount.  I'm also thinking that I'd like to smear something suitable around the housings to ensure a gas tight fit on final assembly.  Any thoughts, bearing in mind this is going to get hot?

Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 16, 2013, 03:37:08 PM
Next up, the valves.  I'll make these by using a length of 1/8" precision ground stainless steel brazed to a stainless disc for the head.  The first problem was that a 3-4mm ER25 collet won't hold a 1/8" (3.175mm) length of rod tightly enough to screw 5BA with a die.  Not major, I used a 1/8" Myford collet instead but I'll need to investigate alternative ER collets in these smaller sizes.

(http://i104.photobucket.com/albums/m180/rod_sally/v2_zps6999a1a5.jpg)

The disc for the head was drilled 3.3mm to give a bit of clearance for the braze to penetrate and then parted off.

(http://i104.photobucket.com/albums/m180/rod_sally/v1_zpsa2918d5d.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/v3_zps580ed5de.jpg)

The last time I did this, on slightly smaller valves, I used brass wire but this time I couldn't seem to get it hot enough for the brass to flow.  I gave up and started again with new bits and some old C4 silver solder which has a higher melting range than some of the other compositions.  Here they are cooling down

(http://i104.photobucket.com/albums/m180/rod_sally/v4_zps2bb525ac.jpg)

The heads were then turned to shape, including the 45 degree seats.  While the topslide was at this angle I also turned the corresponding seats in the valve inserts

(http://i104.photobucket.com/albums/m180/rod_sally/v5_zpsa866c5ca.jpg)

Valve springs were next.  As is common with ETW, there is no mention of the springs at all in the write up or on the drawings.  As most small i.c. designs seem to use 22SWG, this is what I used.  The valve stems are 1/8" diameter so I used a 5/32" mandrel to wind the springs.  12 tpi seemed to look be about right.  The winding bar is just a length of mild steel with a notch filed in it and there is a hole in the mandrel to tether the wire.

(http://i104.photobucket.com/albums/m180/rod_sally/v61_zps43fd0b4c.jpg)

The gearbox on the lathe was set to 12 tpi and once the winding was started, the leadscrew was disengaged to give a couple of close turns

(http://i104.photobucket.com/albums/m180/rod_sally/v62_zps4302d83a.jpg)

Then the leadscrew was engaged to wind the spiral (which I did by hand using the mandrel handle)

(http://i104.photobucket.com/albums/m180/rod_sally/v63_zps2e1d6453.jpg)

and then the half nuts disengaged again to close the spring

(http://i104.photobucket.com/albums/m180/rod_sally/v64_zps096c3cf1.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/v65_zpsa53db8bb.jpg)

A touch on the grind stone finished it off

(http://i104.photobucket.com/albums/m180/rod_sally/v66_zpsc43fa54a.jpg)

These are the components for the valve (inlet) assembly.  The spring cap was a simple turning job with a 5BA thread

(http://i104.photobucket.com/albums/m180/rod_sally/v7_zpsfbc30ea5.jpg)

This is the assembled exhaust valve.  The valve spring strength seems OK, I can't imagine it's at all critical on this type of engine.

(http://i104.photobucket.com/albums/m180/rod_sally/v8_zpsb81af8e2.jpg)

I've still to cut the passages for the inlet from the carb and the outlet to the exhaust.  I'll do that when they are fastened in place but first I think it's about time I made some proper studs.


Title: Re: ETW's Wyvern Gas Engine
Post by: Roger B on July 16, 2013, 03:49:59 PM
Good and interesting work.  :ThumbsUp: This is an engine I had often though about trying to build.

Have members found a lot of problems with casting sets?
Title: ETW's Wyvern Gas Engine
Post by: NickG on July 16, 2013, 04:52:41 PM
Nice work Rod, looks very good. I've never heard of brass valve seats before but they've turned out well. Are you planning on any kind of leak testing device or just wait until final assembly and see what the compression is like. I have never done an ic before but I can
Imagine it helping pin point faults later.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 16, 2013, 05:23:31 PM
The valve seats are bronze, not brass - quite common on small i.c. engines.  I'll see what the compression is like after assembly, one advantage of being able to remove the whole lot if it needs attention.
cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on July 16, 2013, 05:37:14 PM
Nicely done Rod!

Dave
Title: ETW's Wyvern Gas Engine
Post by: NickG on July 16, 2013, 07:57:13 PM
Oh didn't realise that, good to know no exotic steels are necessary!
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on July 16, 2013, 08:32:59 PM
Attentively following your progress Rod and learning new things.  Thanks.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on July 16, 2013, 09:49:21 PM
Ron, I have been following you quietly and learning. Great work on your engine and I like your use of the HDA since I just completed mine. BTW great photos.

Don
Title: ETW's Wyvern Gas Engine
Post by: ths on July 18, 2013, 04:09:27 AM
I've also found minor problems with holding certain imperial sizes in metric ER collets. I've decided to overcome that by getting some imperial collets, as they will generally require minimal tightening of the closing nut. At 3.175 mm, a 1/8" rod is asking for nearly maximum tightening of a 4 mm collet.

Nice work on the valve unit!

Hugh.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 23, 2013, 10:15:19 PM
There's a little bit more to do on the head before I know how long the studs should be.  The combustion space is not cylindrical but is elongated 5/16" high (as bored) but 9/16" wide.  ETW suggests opening this out with a rotary file.  I don't know how he intended to do that since the end at the spark plug is semi-circular in plan view, 9/16" radius.  Anyway, I decided to open it out with a 5/16" ball ended mill.  The largest cutter I can hold in my milling spindle is 1/4" OD shank so the plan was to hold the cylinder head in the collet on the dividing head and the cutter in the lathe spindle.

(http://i104.photobucket.com/albums/m180/rod_sally/cu1_zpse166bb9b.jpg)

The dividing head has 2 seats at right angles - in this configuration it sits at exactly centre height (it should do since it was bored between centres on this lathe) and the key fits snugly in the cross slide tee slots to keep it parallel to the lathe axis.  I was prompted by a comment by Jason on another forum to look out my electronic centering guide which was broken.  A couple of tweaks to the wires and a new spring to contact the battery and it worked again.  That's a 1/2" PGMS bar in the dividing head.

(http://i104.photobucket.com/albums/m180/rod_sally/cu2_zpsef025c9b.jpg)

Centred in X,Y and Z I could now mount the head in the collet in the dividing head and the ball end mill in a collet in the spindle.  I know the inlet and exhaust face is at 90 degrees (6 holes on the indexer) so I levelled this and then rotated through 90 and widened the passage by milling 1/8" either side of the centre.

(http://i104.photobucket.com/albums/m180/rod_sally/cu3_zpscc693b0d.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cu4_zpsf05ce0a3.jpg)

  Result?  Misery  :'(

(http://i104.photobucket.com/albums/m180/rod_sally/cu5_zpse38c710b.jpg)

It looks like I've miscounted the number of holes on the indexer and milled at the wrong angle. 

It gets worse  :o

(http://i104.photobucket.com/albums/m180/rod_sally/cu6_zpsb9d6ce3e.jpg)

I've broken through the valve insert seats, which are required to make the valve assembly gas tight.  They must have been paper thin anyway - a miscalculation somewhere.  I suppose I could live with the slanty combustion space and I could bore out the valve pockets and press in a plug before re-cutting the pockets (properly this time) but in reality it's a scrapper.   I could fabricate a new head from solid and bolt on the rocker arms but I think a call to those nice people at Hemingway is in order.

Ho hum.

 
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on July 24, 2013, 12:22:45 AM
Bummer Rod, and it looked like every thing was going so well. Its still a very interesting project and you have done well with it. Just regroup and attack it again we all get those moments.

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on July 24, 2013, 12:42:39 AM
Hi Rod

I have been following along with your build of the Wyvern and enjoying your progress.

I feel your pain on the head; I did a similar mistake on the exhaust valve chest for my Pacific engine. When I milled the D shaped exhaust port I did it upside down and cut into the valve seat instead of underneath it  :wallbang:. As you have decided I could have also fixed it but found it easier to just order a new casting and get on with it.

Thanks for taking the time to document and post your build here on MEM.

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on July 24, 2013, 09:30:29 AM
Rod, Have you thought of boring it out and making up a cast iron "plug" and having another go?

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on July 24, 2013, 09:33:39 AM
Rod, Have you thought of boring it out and making up a cast iron "plug" and having another go?

Jo

Yes....Give it a shot...you have nothing to loose but trying at this point.

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on July 24, 2013, 11:15:04 AM
Rod, sorry to hear about this. Hope you come up with solution.  :ThumbsUp:
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 24, 2013, 01:00:23 PM
Hi guys, thanks for sharing my pain  :)  OK, I've had a restless night to think about this.  A cast iron plug is out, bearing in mind this is an aluminium head, because the thermal expansion co-efficient of ally is about twice that of iron so the plug would probably become loose at operating temperature.  Here's an extract from the drawing (Moderators - is this OK?).  The exhaust valve is the same as the inlet valve in my version (apart from the flange)

(http://i104.photobucket.com/albums/m180/rod_sally/wyverncheadcs_zpse131fb2c.jpg)

An ally plug might work.  It would need to be a light press fit to keep things gas tight.  The valve assembly would keep the plug from moving upwards and if I put a small top hat flange on the plug that would stop it dropping down - like this

(http://i104.photobucket.com/albums/m180/rod_sally/wyvernCHcs_edited-1_zps0fbef1d0.jpg)

 I think it would work but I'm still inclined to think it's a bodge too far.  I'll give it a go, if only as an exercise.

Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on July 24, 2013, 03:13:47 PM
I was planning on putting cast iron plugs in my Galloway head as I am not happy on the aluminium valve seats. I have seen one of Malcolm Stride's drawings with an iron valve guide in an ali head  ;).  But my Centaur has studded on brass ones  :headscratch:

The head is fairly small, so relative expansion will be only a little .. a good press fit to start...

No problem with the extract. Uk copyright law allows you to publish extracts for the purpose of supporting discussion.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on July 24, 2013, 06:31:42 PM
Yeah I initially thought yes you are right - but then as Jo said, lots of aluminium heads will have steel or iron valve seats and guides pressed into them - probably quite an interference fit mind you and not sure whether you have enough meat left for such a fit? Certainly worth a try.
Title: Re: ETW's Wyvern Gas Engine
Post by: Roger B on July 24, 2013, 06:53:34 PM
Almost all full size engines with alloy cylinder heads have cast iron or steel inserts. I think some used to roll a lip over the insert to keep it in place.
Title: Re: ETW's Wyvern Gas Engine
Post by: michaelr on July 24, 2013, 07:12:31 PM
When I built my Wyvern I had a problem with the valves hitting the spark plug electrode, got wrong with the boss size.

Rather than putting packing washers under the plug, I bored out the spark plug boss and pressed in a shouldered steel boss, I lightly knurled the boss and pressed it in with a coating of JB Weld on the knurling, it has never moved under running conditions or plug removing/ tightening.




Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 24, 2013, 08:26:21 PM
Many thanks for the comments guys.

I think the use of cast iron/steel is a bit of a red herring since I've used bronze inserts to overcome the valve seat in ally issue.  What I need to ensure is that any insert doesn't provide a leak path during compression.  I'm a bit reluctant to use too much pressure on a force fit since I'm not sure how much strain the the head casting can take. It is after all a slightly porous sand casting, not a hi tech alloy.  I'm very interested by michaelr's use of JB weld as a caulk since his use suggests that it can stand up to whatever temperature the head will get to.   

Thanks again

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Maryak on July 24, 2013, 11:21:02 PM
I agree,

JB Weld is your friend when inserting cast iron valve seats into aluminium heads. It's considerably cheaper than loctite and has a higher end point working temperature.

Best Regards
Bob
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 28, 2013, 03:07:24 PM
Experiments complete, I've decide to Ali weld the exhaust valve socket and JB weld the inlet.  I've bored both the sockets with a slight recess.

(http://i104.photobucket.com/albums/m180/rod_sally/CH1_zpscd216767.jpg)



The exhaust plug has a screw thread to ease handling. 

(http://i104.photobucket.com/albums/m180/rod_sally/CH2_zps27a5e34f.jpg)



First I "tinned" the plug by melting some blobs of the braze and then spreading it all around with the stainless steel brush.  The head was then heated and some braze blobbed onto the socket and stirred around with the stainless steel rod.  By this time the plug had cooled somewhat but I placed it in position on top and directed the flame at it until it slid into the socket and then twisted it around.

(http://i104.photobucket.com/albums/m180/rod_sally/CH3_zpse55534f5.jpg)



Looking pretty good from this angle  :)

(http://i104.photobucket.com/albums/m180/rod_sally/CH4_zps6f411a10.jpg)



After cooling, the inlet valve plug and socket were liberally smeared with JB weld and the plug pushed home

(http://i104.photobucket.com/albums/m180/rod_sally/CH5_zpsda3c25d2.jpg)



Ready for milling and drilling when the JB weld has cured.  The excess braze from the exhaust plug is clearly visible butting up to the JB weld on the inlet

(http://i104.photobucket.com/albums/m180/rod_sally/CH6_zps296800dd.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on August 01, 2013, 08:04:03 PM
With the JB weld set I've re-bored the seats for the valves and everything now fits snugly.  The ally braze seems to have worked very well, certainly an option for fabrication.

I drilled the stud holes for fitting the valve assemblies by clamping the cylinder head seat face to an angle plate and lining up the inlet/exhaust port face with a set square, which is at 90 degrees to the valve faces.

(http://i104.photobucket.com/albums/m180/rod_sally/cha1_zpsf2f7067b.jpg)

Then drilled through, using the valve assemblies as jigs,  and tapped on the pillar tool

(http://i104.photobucket.com/albums/m180/rod_sally/cha2_zpsc29e8e66.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cha3_zpsfb318fb6.jpg)

8BA studs for the exhaust valve

(http://i104.photobucket.com/albums/m180/rod_sally/cha4_zps5737c0b6.jpg)

Both valve assemblies in position

(http://i104.photobucket.com/albums/m180/rod_sally/cha5_zpscdc0cb55.jpg)

Here's a couple of pictures of the combustion space.  I cleaned up the inside in the same way as I did the first time, together with a bit of tidying up with a burr in a Dremel to smooth the transitions a bit

(http://i104.photobucket.com/albums/m180/rod_sally/cha8_zps8de0c161.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cha7_zpsd817fdbe.jpg)

I still need to drill through for the spark plug but as I've not decided which plug to use yet I'm leaving that for now.

I guess it will do but there's a nice new cylinder head casting on the bench whispering "do it properly" to me. I shall turn a deaf ear for the present as the inserts have become something of an experiment and I'll carry on with the botch.
Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on August 02, 2013, 12:41:19 AM
Nice save Rod!

The repair looks great :ThumbsUp:

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on August 02, 2013, 12:18:52 PM
What repair I don't see no stinkin repair!...... 8)


Great job of that Rod....Like the pillar tool too!
 :ThumbsUp:
Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on August 02, 2013, 02:23:29 PM
Nice fix  8)

And I too like the GHT Universal pilar tool  :embarassed:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on August 02, 2013, 02:39:19 PM
A really good save Rod.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on August 02, 2013, 04:19:07 PM
Nicely done. Agree with Jo, that pillar tool looks the part.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on August 02, 2013, 10:26:39 PM
Thanks guys.  The pillar tool is great.  I've not broken a tap since I made it.

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on August 03, 2013, 04:14:37 AM
Nice save Rod and thanks for the experiments I learns a few things following you. I really need to get back to my pillar tool thread. Love to see it being used. You did a nice job on it.

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on August 30, 2013, 07:34:46 PM
Now, where was I?  Oh yes, The cylinder head stud holes need facing and drilling so I spot faced in the mill

(http://i104.photobucket.com/albums/m180/rod_sally/aaa1_zpsafecee31.jpg)


and then drilled through for 4BA tapping size on the pillar drill.  I decided it was best to drill the holes where they looked like they best fitted the castings.

(http://i104.photobucket.com/albums/m180/rod_sally/aaa2_zpse75fc2fb.jpg)


I then used the cylinder head as a jig for drilling one hole in the cylinder jacket, the head is located by the cylinder liner which projects beyond the jacket - hence the parallels

(http://i104.photobucket.com/albums/m180/rod_sally/aaa4_zps8e79d52c.jpg)


 tapped this on the pillar tool, opened out the hole in the head to 4BA clearance, inserted a temporary screw and repeated the procedure for each hole in turn

(http://i104.photobucket.com/albums/m180/rod_sally/aaa3_zpsd831f803.jpg)


A set of studs were then made and inserted

(http://i104.photobucket.com/albums/m180/rod_sally/aaa6_zps77188a66.jpg)


The head slid onto the studs very nicely with no shake and without having to ease the holes- testament I think to the pillar tool ensuring that the tapped holes were perpendicular.  The stud holes in the jacket seem to be in the right place

(http://i104.photobucket.com/albums/m180/rod_sally/aaa5_zps31294e50.jpg)

but the same can't really be said for the head.  No harm done, just not quite as neat as I would like

(http://i104.photobucket.com/albums/m180/rod_sally/aaa7_zpscf9a0f31.jpg)

The job that I've been putting off is making the inlet and exhaust passages in the valve assemblies.  These were bolted in position and the cylinder head set up on the dividing head in the mill.  I don't have a 5/16" slot drill long enough to do this so had to use an end mill, which meant that I needed to put a smaller slot drill through first to do the centre cutting.  The tailstock is just providing a bit of steadying pressure.

(http://i104.photobucket.com/albums/m180/rod_sally/aaa8_zpsa03e0356.jpg)

It all seemed to work OK. 

(http://i104.photobucket.com/albums/m180/rod_sally/aaa9_zpsfe64d727.jpg)

Phew!





Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on August 30, 2013, 07:43:30 PM
Nice to see some progress on this engine. (and more use of the UPT  :embarassed:)

That is a bummer with the stud breaking through on the outside on the under side of the head, it wasn't too hot on the top  :facepalm2:... Are you thinking of building it up with some JB weld or something?

Jo

Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on August 30, 2013, 07:56:11 PM
Quite a bit of fettling will be required to make the head blend in with the the jacket.  I've got a spare head casting now.  The current plan is to see if I can get it the engine to run using the bodged head, as a test of the inserts, and then make a new head (properly this time).

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 01, 2013, 08:58:19 PM
This is the  casting stick for the 2 rockers

(http://i104.photobucket.com/albums/m180/rod_sally/r1_zps4951f167.jpg)

The finished bosses protrude 1/8" on one side and 1/16" on the other.  A little bit of filing ensured that the arms sat level and firm on the 2 central bosses and the valve end.   I took the bosses down to 1/8", turned it over and milled the other side down to the total required thickness which was 5/16"

(http://i104.photobucket.com/albums/m180/rod_sally/r2_zps711e9188.jpg)

This demonstrates how the casting can make you look like an idiot.  The hole in the small boss (which will be tapped 4BA) clearly has to go in the middle of its boss and the pivot hole needs to be 1 1/8" from this, which of course isn't in the centre of that boss.

(http://i104.photobucket.com/albums/m180/rod_sally/r3_zps2968fd0d.jpg)

 I drilled the holes at the correct spacing and split the casting with a junior hacksaw
 
(http://i104.photobucket.com/albums/m180/rod_sally/r4_zpsa9ffcedf.jpg)

For aesthetic reasons the plan to leave the arms as cast had to go out of the window, so I turned up a stub mandrel to fit and machined the fulcrum bosses on both sides

(http://i104.photobucket.com/albums/m180/rod_sally/r5_zps4ed9548f.jpg)

This end of the rocker has a blind hole for a push rod and is supposed to be 1/4" diameter cylinder

(http://i104.photobucket.com/albums/m180/rod_sally/r6_zpsd1cb9bcf.jpg)

There was just room to fasten a 1/4" filing button with an 8BA screw, the blind screw hole will be opened out later
(http://i104.photobucket.com/albums/m180/rod_sally/r7_zps26ef7f59.jpg)

3 hours filing later (which I rather enjoyed) and we have 2 reasonable rocker arms

(http://i104.photobucket.com/albums/m180/rod_sally/r8_zps031f1166.jpg)




Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on September 01, 2013, 10:03:57 PM
Hey Rod,

Who's dividing head is that?...

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on September 01, 2013, 11:04:34 PM
Its Rod's dividing head  ;D

But seriously it looks like the Alan Timmins design to me.

Phil
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 01, 2013, 11:14:28 PM
Dave,

It's the Timmins design, originally published in Engineering in Miniature, the castings are available here http://www.blackgates.co.uk/ (http://www.blackgates.co.uk/).  It is available with either a 40:1 or 60:1 wheel.

I modified the design to use the plates and fingers from my GHT HDA.  I preferred the design to the VDH because it has a proper spindle with a Myford nose with 2MT socket and because in one orientation it sits at centre height on my Super 7 cross slide but rotate it through 90 degrees and it sits high enough on the milling machine to mount a decent sized chuck  (actually, the real reason I made it was because the casting came with the bits and bobs with my lathe) but it has always seemed to me to be a better design than the VDH for the Myford owner.

Aww Phil, I was going to use that joke >:(

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on September 02, 2013, 12:50:54 AM
Thanks Guys!....

I'd like a dividing head with a SB9 spindle nose and internal taper...for similar reasons...but will also be capable of mounting in my mill vise.

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on September 02, 2013, 07:19:18 AM
 :lolb: I enjoyed it.

It looks like you have a pretty impressive workshop there Rod. I might just have to drop in one of these days if I find my way coming back from Reading to find out if you have any other desirables hiding away :naughty:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 02, 2013, 12:04:29 PM
Jo,

You're always welcome to pop in and see my desirables - although you might be disappointed by the size.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on September 02, 2013, 03:16:59 PM
Thanks Rod,

I might just take up up on it  :naughty:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 09, 2013, 07:39:56 PM
I thought I'd have a go at the flywheels next.  The iron castings have some flash and the registration between the 2 halves isn't great, as we shall see.

(http://i104.photobucket.com/albums/m180/rod_sally/fw1_zps9b9cbb5e.jpg)

A bit of work with a file got rid of the flash and the worst of the mis-registration step on the spokes

(http://i104.photobucket.com/albums/m180/rod_sally/fw2_zps51237580.jpg)

The flywheel was mounted on the faceplate, resting on 3 ally pads and centered so that the inner edge of the rim was running as true as possible, since I don't want to machine that.

(http://i104.photobucket.com/albums/m180/rod_sally/fw3_zps703c1c1e.jpg)

There is a generous machining allowance on the casting, with about 1/8" to come of each face and the radius.  The rim was turned in the highest backgear - this seemed the most comfortable speed.

(http://i104.photobucket.com/albums/m180/rod_sally/fw4_zps65d4de6d.jpg)

I had to use some old school methods to measure the diameter

(http://i104.photobucket.com/albums/m180/rod_sally/fw5_zps985a2d2a.jpg)

The rim and the hub are reasonably centered and concentric on this side, which will be the outboard side of the flywheel when mounted on the engine

(http://i104.photobucket.com/albums/m180/rod_sally/fw6_zps77372b3f.jpg)

After machining one side I turned the casting around and centered it on the rim outer using the DTI

(http://i104.photobucket.com/albums/m180/rod_sally/fw7_zpsf4da2e0a.jpg)

As I mentioned above, the 2 sides are not well registered, so the inboard side of the flywheel looks rather eccentric

https://www.youtube.com/watch?v=aPh2Z8CkD3Y

The flywheels are mounted on to the crankshaft using a split, tapered collet so the bore was drilled and then turned with the topslide set over to 5 degrees.  I left the topslide at this setting for making the second flywheel and the collets

(http://i104.photobucket.com/albums/m180/rod_sally/fw8_zpsc693685a.jpg)

So, I've now got a pair of flywheels that look OK from the outside, a bit of Dremel work will blend the various radii

(http://i104.photobucket.com/albums/m180/rod_sally/fw9_zps5acc845d.jpg)


Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 09, 2013, 07:54:46 PM
The collets are a simple turning job.  The job was drilled and then bored 3/8" and the taper turned.

(http://i104.photobucket.com/albums/m180/rod_sally/c1_zps1cb3cae0.jpg)

I then transferred the job in the chuck to the mill and split the collet with a saw

(http://i104.photobucket.com/albums/m180/rod_sally/c2_zpsf4d0787b.jpg)

The job then went back to the lathe to be parted off.  I thought I might have trouble parting across the slit but it was trauma free.  There's another one to make.

(http://i104.photobucket.com/albums/m180/rod_sally/c3_zps18453874.jpg)


Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on September 09, 2013, 09:29:50 PM
Commiserations on the flywheel miss alignment is a common problem :shrug:

 :headscratch: Ok Rod forgive me it must be late.. what are the collets for?

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Dan Rowe on September 09, 2013, 09:56:31 PM
The flywheels are mounted on to the crankshaft using a split, tapered collet so the bore was drilled and then turned with the topslide set over to 5 degrees.  I left the topslide at this setting for making the second flywheel and the collets

Rod, will it be a plate and screws that secures the collets to the flywheel?

Dan
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on September 09, 2013, 09:58:41 PM
 :facepalm:
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 09, 2013, 10:16:35 PM
Sorry, should have been clearer.

The ends of the crankshaft are turned 3/8" diameter up to a shoulder inboard and threaded on the outboard side.  The collet slides over the plain portion with small end of the taper towards the thread.  The taper hole in the flywheel fits over the collet and is pushed tight by a nut, which then pushes the flywheel to tighten the collet on the shaft and the flywheel on the collet.  ETW claims that this is a more positive method than a key.  It is similar to the way that prop drivers are often fitted to model aero engines (well, the 2 I've built anyway).

Thanks for looking.

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Dan Rowe on September 09, 2013, 10:55:12 PM
Rod,
One of the diesel engines I worked on had tapered collets for the cams. There was a nut on a threaded section of the small end of the collet so a very similar system.

Dan
Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on September 09, 2013, 11:51:58 PM
Nicely done Rod,

The flywheels look great!

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 27, 2013, 08:26:02 PM
Hello again.  What I thought would be a trivial job turned out to be more difficult than I expected - making the retaining nuts for the flywheels.  These need to match 3/8" 26 threads on the ends of the crankshaft.  I have some 3/8" Whitworth hex steel which looked about the right size to make a neat job.  So - chuck, drill, tap, chamfer and part.

Drill was straightforward

(http://i104.photobucket.com/albums/m180/rod_sally/nut1_zpsfa20670b.jpg)


My usual set up for tapping is to use the mandrel  handle and hold the tap in the drill chuck

(http://i104.photobucket.com/albums/m180/rod_sally/nut2_zps13b575bd.jpg)

The first problem was that the handle, which grips in the mandrel with an expanding collet wouldn't hold after the tap had gone had gone in about 3 threads.  OK, I could pull the belt round by hand.  Then, after another thread depth or so, the tap was spinning in the drill chuck, even after I changed to a keyed chuck.  The solution is to cut the thread first, which is what I always do on threads bigger than 1/2".  I found that I don't have a threading tool small enough to go in a 3/8" hole  :(.  I resorted to a tap wrench guided by the tailstock to start with - always a bit of a juggle while pulling the mandrel around with the belt.  I really must make a spring centre (and grind up a small internal threading tool)

(http://i104.photobucket.com/albums/m180/rod_sally/nut3_zpsca14e44e.jpg)

Parting was trouble free

(http://i104.photobucket.com/albums/m180/rod_sally/nut4_zps775d00ba.jpg)


and I stopped part way through to chamfer the edge (so that the nicely machined surface was against the flywheel

(http://i104.photobucket.com/albums/m180/rod_sally/nut5_zpsd62cbfc3.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/nut6_zps1630c380.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 27, 2013, 10:19:17 PM
I  had a go at making the cams next.  These have flat flanks (for a roller follower) with 1/8" lift.  The inlet has a 120 degree lobe and the exhaust 130.  I used my cam generating program to print out a set of co-ordinates to mill the cams in the vertical mill with the blank in the dividing head.  The program actually generates cams with 3 radii, the base, flank and nose.  By putting in a very large radius (10000") for the flank, this is essentially flat.  The calculated values for velocity and acceleration will be nonsense because of the roller rather than a flat follower but the the profile is correct.  I first turned the blank with a 15/32" boss and an OD of the base circle (1/2") plus the rise (1/8")

(http://i104.photobucket.com/albums/m180/rod_sally/cam1_zps019fce5f.jpg)

This is the set of co-ordinates for rotating the blank.  I've used 3 degree intervals, which is half a turn of the handle on the dividing head.  Slightly concerned about this since these cams are larger than I've made before and there may be some faceting - we shall see.

(http://i104.photobucket.com/albums/m180/rod_sally/cam3_zps1636dad6.jpg)

The blank was centered on the Y axis, because I shall need to drill a hole through the boss, and the Y axis zeroed on the DRO.  The Z axis was the zeroed with the cutter touching the OD of the blank and then slid out of the way before lowering it by 1/8" and re-zeroing

(http://i104.photobucket.com/albums/m180/rod_sally/cam2_zpscb261e7c.jpg)

The first cut was taken across the blank at a tangent to the base circle.

(http://i104.photobucket.com/albums/m180/rod_sally/cam4_zpsa2e64a80.jpg)


The blank was then rotated by 3 degrees, the table lowered to the displacement read off from the table of offsets and a cut taken.  I settled into a rythm - rotate, cut,  mark off.  The lobe is finished here and the rest of the rotation cuts the base circle back at the zero offset.  Each cam took about 40 mins.

(http://i104.photobucket.com/albums/m180/rod_sally/cam5_zpsd1f1ad0f.jpg)


The Y axis was zeroed and the pin hole drilled  1/16"

(http://i104.photobucket.com/albums/m180/rod_sally/cam6_zpse4b8265e.jpg)


After returning the chuck to the lathe the cam was parted off.  There is a hint of faceting here, about the same roughness as the machining marks.  This was easily removed with a dead smooth ( 6 cut) file

(http://i104.photobucket.com/albums/m180/rod_sally/cam8_zps04f6f218.jpg)


The pair of cams.  These will be case hardened.

(http://i104.photobucket.com/albums/m180/rod_sally/cam9_zpsde4d7b32.jpg)

Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on September 28, 2013, 12:40:35 AM
Beautiful work rod, I like the lobs they came out great. Is that an excel spread sheet you used to do the calculations with?

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 28, 2013, 07:40:05 AM
Don, 

Yes,  the program's current incarnation is an Excel spreadsheet.  It's the one I attached to my comment in Nick's CamCalc thread.  I pasted the calculated  values into word for printing.

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 30, 2013, 07:42:55 PM
The pivots for the rocker arms and the roller cam followers are similar straightforward turning jobs.  The rocker pivots have an eccentric spigot to allow for clearance adjustment.

The 3/8" blank was mounted in the 4 jaw independent and roughly centered before turning the 2 diameters. 

(http://i104.photobucket.com/albums/m180/rod_sally/piv1_zpsad62554d.jpg)


The drawing calls for the spigot centre to be offset by 10 thou but I doubled this to give a greater range of adjustment - the smaller diameter is still wholly within the larger.

(http://i104.photobucket.com/albums/m180/rod_sally/piv2_zpsb3c29ddb.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/piv3_zps5e4a3da5.jpg)


The head was tidied up and then the screw slot was cut in the milling machine in similar manner to splitting the collets.

(http://i104.photobucket.com/albums/m180/rod_sally/piv4_zps1a08a36f.jpg)

ETW designed hardened steel rollers rotating on hardened steel pivots for the cam followers but I found these in my collection of ball races

(http://i104.photobucket.com/albums/m180/rod_sally/piv5_zpsf8550433.jpg)

The OD and ID are the same as the design but they are a bit narrower.  I therefore kept the pivot design the same but in un-hardened mild steel.  I will put washers either side of the ball races to bring them to the middle of the cams

(http://i104.photobucket.com/albums/m180/rod_sally/piv6_zps30e9e226.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/piv7_zpsc50148e0.jpg)

Title: Re: ETW's Wyvern Gas Engine
Post by: Lofty76 on September 30, 2013, 08:38:47 PM
Rod, is your dividing head not a standard 40:1?

I make half a turn equal 4.5 degrees, not three.

Just checking

Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 30, 2013, 11:09:54 PM
60:1  The design mirrors the George Thomas Headstock Dividing Attachment which utilises the Myford 60 tooth bull wheel.

Cheers and thanks for taking an interest,

Rod




Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on September 30, 2013, 11:17:25 PM
I had similar results when I was working on my Seadog build....the flats on the cam came right out with a file though.

Title: Re: ETW's Wyvern Gas Engine
Post by: swilliams on September 30, 2013, 11:25:47 PM
Really nice job your doing Rod! I really like the Wyvern.

Steve
Title: Re: ETW's Wyvern Gas Engine
Post by: Lofty76 on October 01, 2013, 05:18:09 PM
Thanks Rod  :D
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on October 02, 2013, 04:46:25 PM
Looking really nice Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 03, 2013, 11:46:48 PM
Hello again  :).  It's taken me rather a long time to work out how to make the helical gears but I seem to be there now.  Machinery's Handbook gives some formulae for calculating the various parameters for milling helical gears.  I've put these into a spread sheet.

(http://i104.photobucket.com/albums/m180/rod_sally/gearcalcs_zpsf5111001.jpg)

ETW calls for a pair of gears, 32DP. 8 and 16 tooth, both the same diameter at 5/8".  The magic helix angles to get this size are 26.6 degrees for the 16 tooth and 63.4 for the 8 tooth.  I've bought a set of 0.8 MOD gear cutters from CTC, these work out as identical to 31.75DP.  The lead for the gears are 3.536 and 0.885 inches respectively.  The handbook gives two options for choosing which cutter to use.  Experience has taught me that the approx method seems to give a thin tooth so I went for the more accurate calculation which brings the diameter of the cutter into account.  This is actually quite important because it is interference from the cutter that changes the shape of the tooth - the smaller the cutter the better. However, the calculation calls for a 273 tooth cutter for the 63 degree gear.  For spur gears it is assumed that a cutter can go from 135 teeth to infinity (a rack).  I'm not sure that this applies in the helical gear case since the calculation is determining the thickness of the cutter that compensates for the interference.  Whatever;  135 to a rack is the best I can do.  The gear cutter needs to be set over to the helix angle and I'm using my milling spindle mounted on the swivelling vertical slide on the lathe cross slide.  A bit of trigonometry allowed me to calculate and measure the angle accurately.

(http://i104.photobucket.com/albums/m180/rod_sally/gear5_zps7d769385.jpg)

This is the milling set up

(http://i104.photobucket.com/albums/m180/rod_sally/gear8_zpsba52babd.jpg)

The gear blank needs to rotate as the gear is cut according to the lead.  My lathe has a gearbox but is a conversion from a non-gearbox machine:  consequently I've got loads of change wheels and the metric conversion banjo so I can arrange the changwheels in lots of combinations.  In theory the biggest lead I could generate would come from 75,70,65 as drivers to 20,20,21 as drivens - with the selector set to 8tpi this gives a max lead of 5 inches.  I've written a spreadsheet to calculate all the possible combinations together with the gearbox selector.  For the 63 degree gear I came up with an exact lead of 0.885 from drivers 28,65,75 to drivens 21,24,34 with the gearbox set to 9.  For the 26 degree gear lead of 3.536 the best i could get was 55,65,70 to 21,20,21 and the box set to 8 giving 3.547.  I can live with an 11 thou error in 3 1/2 inches.  This is the gear set up for the 3.547 inch lead

(http://i104.photobucket.com/albums/m180/rod_sally/gear4_zps7a62df6b.jpg)

I proved the train by measuring the lead for a partial rotation of the spindle by turning the lead screw handle

(http://i104.photobucket.com/albums/m180/rod_sally/gear6_zpscb82767a.jpg)

The gear blank needs to be indexed for each tooth.  The method I came up with is as follows.  I used a direct indexing method using the HDA plates.  There is a 32 hole ring which allows me to divide into 8 or 16.  I made up an indexing arm that clamps to the blank and has an adjustable indexing pin.

(http://i104.photobucket.com/albums/m180/rod_sally/gear7_zpsef5ea8c5.jpg) 

You'll notice I've marked each fourth hole for the 8 tooth wheel  (it's easy to miscount - I know).  Ideally the blank would be mounted between centres but unfortunately the 
vertical slide gets in the way.  I made up a collet to hold the blank in my 3 jaw chuck.  This has a 3/8" hole reamed through and is split so that tightening the chuck jaws tightens the collet on the blank.  The collet holder also has the dividing plate mounted on it.  There is a peg which sits against one of the chuck jaws.  The blank can then be rotated to the next index hole, the peg snugged against the chuck jaw (always the same one) and the chuck tightened up (always using the same key hole).  Repeated trials gave a total run out using this system of 3/4 thou.  The gear blank was made with a 3/8" spigot on one end and 0.627 on the other.

(http://i104.photobucket.com/albums/m180/rod_sally/gear1_zps863cf235.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/gear2_zpseac5103a.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/gear3_zps2e547dca.jpg)


The cutter was lined up over the centre of the blank and the cross slide locked.  The depth of cut was set using the vertical slide.  The cutter was set in motion and advanced by turning the lead screw by hand.  After each cut the vertical slide was raised, the lead screw rotated backwards until the cutter was out of the way, the chuck loosened and the blank advanced to the next index hole.

(http://i104.photobucket.com/albums/m180/rod_sally/gear9_zps2fabf9ed.jpg)

  I've made a pair of gears in aluminium that seem to be OK.  Milling helical gears is something of an approximation so, while not perfect, they seem to work OK for our purposes.  I made the total cut 2 thou less than the calculated tooth depth since earlier trials seemed to be cutting the teeth a bit thin.  I need to order some more suitable materials for the real gears - I'll use free cutting mild steel for the pinion and brass for the follower but I've got neither in 3/4" (or 18mm) in stock. 

It's been an interesting learning experience with a few false starts but it seems to work.  It's been good to find a use for all those changewheels.

Cheers for now, I should be able to make better progress this week.

Rod

Edit: duplicate picture removed

Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on November 04, 2013, 02:25:36 AM
Cool set up Rod, did you use R8 collets in you cutter spindle? Thanks for showing, I have not cut a bevel gear yet, but like you I need to get some practice doing it.

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: swilliams on November 04, 2013, 04:26:11 AM
Looks great Rod. Love the whole arrangement. I'll have to read your entire post more carefully tonight when I have a little more time.

Steve
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 04, 2013, 07:46:39 AM
Well done Rod :ThumbsUp: Now that it is set up what ever you do don't move anything  :naughty:

I take it that you will be cutting a couple of spares just in case. If not for you then for some other poor unsuspecting person who decides to make a Wyvern. I am just pleased I have the ones for my Centaur  ;D

Any chance of making your spreadsheet available for others who might need to make some of these  ;)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on November 04, 2013, 08:42:09 AM
Tangler

Well done on those gears, I really appreciate the effort it took to end up with those looking so good.  :ThumbsUp:
As Jo said, I would love to see your spreadsheet made available.

Jo

Are your Centaur timing gears the ones that come with the kit, ie the camshaft one is a large bronze one that needs a scallop taking out of the main casting for clearance.

Do you want a pair of steel gears like the ones Tangler has made which are both the same diameter ?
My late father made a batch of them for the Centaur on his tangential head gear hobbing machine, I still have one pair left that I could be persuaded to part with if the price collet was right  ;)

Phil
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 04, 2013, 09:02:58 AM
Phil, you keep trying :lolb: . If you look on the end of the crankshaft you should just about see the first of the gears:

(http://i214.photobucket.com/albums/cc12/jothoms/Other%20engines/IMG_3211-1.jpg)

They are both the same diameter  ;).

I am trying not to look at this set of castings.. I already have one infernal combustion engine that is taking up valuable workshop space that does not work yet  :rant:.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 04, 2013, 09:26:10 AM
Folks,

Thanks for your interest.  I've appended the helical gear spreadsheet.  Just change any of the parameters under the pink headings and the rest should re-calculate.

I've also appended my change gear calculator.  This has a visual basic component so may cause some issues with virus checkers.  Running this can be a bit flaky, I think there may be issues with how memory is released so the program locks up.  I find it best to come out of EXCEL after each calculation and start again.  The calculation times can be lengthy since it looks at every combination of 6 changewheels and the gearbox (which is effectively a variable pitch leadscrew).

I hope they are useful,
 
cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 04, 2013, 05:32:46 PM
Don,

The milling spindle has 1 MT.  The CTC gear cutters are 16mm i.d.  I made the holder from a 1MT blank end arbour, it fits all my bought gear cutters: .8, .5 and 0.4 MOD which are roughly equivalent to 32, 50 and 64 DP.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 08, 2013, 06:47:27 PM
This is the inner camshaft bearing bracket.  It supports the crankshaft end of the camshaft.   The centre of the camshaft is 3/8" from the side of the bedplate.  I decided to use the hole through the bracket as the datum so the casting was held in the 3 jaw and drilled through and reamed.

(http://i104.photobucket.com/albums/m180/rod_sally/ib1_zps7189d9d4.jpg)

I then used a boring bar to face one end.

(http://i104.photobucket.com/albums/m180/rod_sally/ib2_zpsf101f8f9.jpg)

I turned up a mandrel from 1/2" precision ground MS, mounted the casting on this and turned  a 3/8" OD on the stub before transferring to the dividing head on  the milling machine.  The axis of the dividing head is set to zero on the Y travel so I was then able to mill the mounting flat at the correct distance

(http://i104.photobucket.com/albums/m180/rod_sally/ib3_zps2166c9af.jpg)

and square up the 2 sawn sides after rotating through 90 degrees

(http://i104.photobucket.com/albums/m180/rod_sally/ib4_zpsca04e13b.jpg)

I'll drill the mounting holes when I'm assembling the camshaft.

Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 20, 2013, 11:27:28 PM
The inner camshaft bearing bracket sits under the crankshaft inboard of the flywheel.  The outer bearing bracket sits on a pad on the side of the cylinder head.  This pad needs to be machined so that I can make the outer bracket to size such that camshaft is at right angles to the crankshaft.  Consequently the cylinder and head need to be fastened to the base, which means I had to spot face the cylinder jacket. A new rule I've made myself is that if a job can be made easier with a jig, fixture or gizmo then don't bodge it - make it.  Consequently I've made myself a cross-drilling jig.  The centre hole is reamed 1/2", so that I can chuck a piece of 1/2" PGMS in  collet chuck and easily drill a bush to any size.  I used it for the first time to drill the tapping hole for the grub screw on the spot facer.

(http://i104.photobucket.com/albums/m180/rod_sally/crossjig_zpse5b8dd19.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/sf1_zps804f0131.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/sf2_zps39cc5dde.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/sf3_zps0e43dd7e.jpg)

and make some studs

(http://i104.photobucket.com/albums/m180/rod_sally/hgc_zps875e4ced.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/hgd_zpsed4ec8d2.jpg)

I also need the gears to mesh properly.  So I made the real ones.  This new toy makes setting up a lot quicker.  How accurate it actually is I don't know - it reads to 0.1 degree and is certainly good enough for this purpose

(http://i104.photobucket.com/albums/m180/rod_sally/hga_zps7e258de2.jpg)

The gears are from leaded steel and brass.  They should be good, I made a blood sacrifice  :o  The ends of the steel gear are sharp!

(http://i104.photobucket.com/albums/m180/rod_sally/hgb_zps8fae4190.jpg)

Before I do any milling, the new rule says that I ought to make a taper extracting nut for the milling machine rather than bashing the end of the draw bar with a 2lb lump hammer.  Fortunately the end of the spindle is threaded 1 1/8" x 12 to take the Myford collets.  The central hole is just big enough to clear the large end of a 2MT.

(http://i104.photobucket.com/albums/m180/rod_sally/mnut1_zpsfbcc6af0.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/mnut2_zps502bfdba.jpg)

Cheers for now,

Rod




Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on November 21, 2013, 01:12:25 AM
Hi Rod

Your engine is looking great; you have made amazing progress since April. The helical gears are especially nice; I hope to be able to give that a try some day.

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 21, 2013, 07:31:56 AM
 :ThumbsUp: I like your new rule. I know I am not that good myself  ::) maybe the Sixis will teach me to be better.

And real studs  :Love: they are such a necessity to make an engine look just right but then I never doubted you would make it properly Rod  8).

Sympathies with the sharp edges to the gears, easy to do.
---
Can you think of any other desireable engines that Westbury did that I might need to make  :naughty: .. I have the centaur, you have the Wyvern are there any other real characters he did? Even ones that were thought to be long gone, there is a good chance tomorrow that they will be there ;)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: pgp001 on November 21, 2013, 07:58:42 AM
Jo

Put "Westbury" in the search box of this web page, you will get some good ideas from the results.

http://www.itech.net.au/modelengineer/

Phil
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 21, 2013, 08:27:02 AM
 :lolb: And that is the problem Westbury was one of the greatest model engineers that ever lived and that to be able to identify what engine castings I need to seek to bring home with me, before tomorrow when I get the chance of them, is not going to be easy.


Ron's MEN pages lists just the engines but there are still so many of them  :insane:.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 21, 2013, 09:58:28 AM
Jo,

I, too, revere ETW.  Making one of his designs was a major factor in choosing the Wyvern for my open crank project.  His forte was innovation and practical design so there isn't much amongst his designs that makes a good mantlepiece model - probably the Vulcan beam engine is the prettiest that I've seen.  Personally, I think his greatest triumph was the 1831 engine (Wallaby).  Together with a working magneto and radiator that makes an impressive installation.

Have fun fossicking,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on November 21, 2013, 10:21:25 AM
As Jo says MEN has a good list, but that does not include the unpublished designs that Jo may be able to get here hands on.

http://modelenginenews.org/etw/etw_engines.html
Title: Re: ETW's Wyvern Gas Engine
Post by: metalmad on November 21, 2013, 10:30:20 AM
What, Did someone just say unpublished "ETW" Designs
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 21, 2013, 11:18:09 AM
What, Did someone just say unpublished "ETW" Designs

 (http://smileys.on-my-web.com/repository/Others/others-180.gif)

So I have been told  ;).

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 22, 2013, 02:27:26 PM
As mentioned, the mounting pad for the crankshaft bracket on the cylinder head needs to be machined parallel to the inner bracket mounting under the crankshaft.  On setting this up I decided that a screw jack would be useful so made one.

(http://i104.photobucket.com/albums/m180/rod_sally/cpad1_zps2167bbad.jpg)

The assembly was mounted on a the angle plate and squared up with a dial gauge on the previously machined surfaces.  I had to have the angle plate on the outside because otherwise it would restrict the Y travel of the mill too much, which made the view slightly awkward.  I was not too greedy with the depth of cut and everything went OK

(http://i104.photobucket.com/albums/m180/rod_sally/cpad2_zpsa43d7acd.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 22, 2013, 06:02:12 PM
Rod,

I thought you might be interested to see Westbury's original Wyvern:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 22, 2013, 09:04:28 PM
That was a kind thought Jo, thanks.  I guess ETW's main castings are iron rather than light alloy - I wish mine were.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 22, 2013, 10:00:05 PM
While the engine was mounted on the angle plate I thought to mill the flange mount for the water inlet/outlets and bring the rocker mounting arms to thickness.  One side was fine but I couldn't get enough travel on the mill to do the other side.  Even when I took the angle plate of the milling table I still couldn't manouver it into a position to mill the areas I needed to.  I had to resort to bolting it to the table.

(http://i104.photobucket.com/albums/m180/rod_sally/DSC_2407JPG20131122_0001_zpsf7a3f10b.jpg)

I think I need to to look at getting (or making) an angle plate that is better matched to the size of the mill and spacing of the t slots.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 22, 2013, 10:04:38 PM
What, Did someone just say unpublished "ETW" Designs

Although Edgar Westbury was the mainstay of Model Engineer for many years he also designed small commercial engines and some units for clandestine work during WW2.  I guess the prototypes for some of these designs may still exist amongst the collection.

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Maryak on November 22, 2013, 10:53:03 PM
The name Wyvern has been niggling me for some time and suddenly I remembered, when we came to Oz, Dad's 1st car was a Vauxhall Velox and it's baby sister was the Vauxhall Wyvern.

Did ETW work for Vauxhall, (General Motors)?

Best Regards
Bob
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on November 23, 2013, 07:39:13 AM
You may want to look into an angle plate without webs, that way you can bolt work to the "inside" of the angle which will keep it over the table. May have to skim the inner edge as they are not always machined true.

J
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 23, 2013, 10:55:27 AM
Jason,

Good point.  I think I can do something with one of these http://www.axminster.co.uk/ground-angle-plates (http://www.axminster.co.uk/ground-angle-plates).

Axminster are now dangerously convenient :o

cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on November 23, 2013, 01:14:03 PM
Yes best not tell Jo they now have a place in Basingtoke.

J
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 23, 2013, 01:40:35 PM
It's OK, they're mostly wood orientated :o  She wouldn't want to go in.
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 23, 2013, 03:20:50 PM
 :lolb:

No fear I have found a much better place to go tool shopping the problem is the proprietor has convinced me that I now need

(http://smileys.on-my-web.com/repository/Love/love-094.gif) a Hardinge HLV and a Schaublin 70.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 25, 2013, 07:40:19 PM
As michaelr kindly pointed out early in this build, there are clearance issues with the gears and the supporting bracket - it rather looks as if the design considered the PCD rather than the OD

(http://i104.photobucket.com/albums/m180/rod_sally/csb1_zps9c98dc9d.jpg)

Not a major problem to fix

(http://i104.photobucket.com/albums/m180/rod_sally/csb2_zpsc0f2318c.jpg)

The bracket needs to be positioned to give good meshing of the gears.  The piece of paper trick doesn't really work with helical gears so I positioned them so they felt good with a tiny bit of backlash, supported against the feeler gauges.

(http://i104.photobucket.com/albums/m180/rod_sally/csb3_zpsa3ee2464.jpg)

I was then able to drill through the hole in the bracket and tap 6BA.  I now needed to get the crankshaft parallel with the base so it was back on the angle plate and squared up against  the machined face.

(http://i104.photobucket.com/albums/m180/rod_sally/csb5_zpse153e465.jpg)

I machined the outer support bracket in similar fashion to the other end.  It was positioned by passing the camshaft through both and then levelling up with an elephant's foot on the DTI

(http://i104.photobucket.com/albums/m180/rod_sally/csb6_zps46c25460.jpg)

I was then able to drill through, tap and put a screw in.  The other end was then drilled and tapped through - I had to use a countersunk screw to keep the gear clearance.

(http://i104.photobucket.com/albums/m180/rod_sally/csb7_zpsb6571873.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/csb8_zpsdfd34e0b.jpg)

It's beginning to look like an engine :)

(http://i104.photobucket.com/albums/m180/rod_sally/csb9_zps9fee168d.jpg)




 
Title: Re: ETW's Wyvern Gas Engine
Post by: metalmad on November 25, 2013, 11:48:30 PM
Its Lovely Rod :praise2:
Pete
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on November 26, 2013, 12:30:08 AM
Beautifully done Rod, I have been learning a lot following this build. Your engine looks a treat. I like......... :ThumbsUp:

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on November 26, 2013, 12:47:10 AM
Hi Rod

I bet it's a great feeling to have that side shaft spinning it it's bearings; beautiful work!

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Stilldrillin on November 26, 2013, 07:18:38 AM
That's looking first class Rod.  :ThumbsUp:

All coming together nicely.......   :praise2:

David D
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on November 26, 2013, 05:35:25 PM
Thanks guys, it's getting there.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: smfr on December 01, 2013, 04:15:36 PM
I've been following along, Rod, watching and learning  :D Keep it up  :ThumbsUp: :ThumbsUp:

Simon
Title: Re: ETW's Wyvern Gas Engine
Post by: Roger B on December 01, 2013, 04:17:36 PM
It looks really good  :ThumbsUp: :ThumbsUp:
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on December 13, 2013, 08:15:27 PM
The valve gear is nearly ready for assembly.  The inlet valve is actuated by a push rod that ends in a fork that fits over the cam shaft, the cam follower being screwed to the side of the fork.  This rather intractible casting is for the fork.

(http://i104.photobucket.com/albums/m180/rod_sally/fork1_zps864de1f7.jpg)

The first task was to mill the fork to final thickness. 

(http://i104.photobucket.com/albums/m180/rod_sally/fork2_zps9789621d.jpg)

Note the parallels.  Santa has made an early visit to the Tangler household this year

(http://i104.photobucket.com/albums/m180/rod_sally/Fork3_zps79032666.jpg)

Very useful, much better that the scraps of bdms I have been using.  The old whited bearded gent also brought this:

(http://i104.photobucket.com/albums/m180/rod_sally/drill_zps011dcf53.jpg)

I had got fed up with drilling triangular holes with my old drill which has a rather sloppy quill - it was also a bit small and has given me trouble getting jobs mounted on an angle plate under the drill bit.  This was the only one I could find from the usual suppliers that gave any sort of guarantee on the run-out.  It is made from the usual cast-in-gravel iron but the run-out on the spindle is undetectable- pity the same can't be said for the supplied 5/8" drill chuck, I've used a 1/2" Jacob's chuck I had which is much better and is easy to change since the drill has a 2MT socket.  The tram round the edge of the table is also very good at under 1 thou all round.

A 1/4" slot drill was used to cut the slot to go over the cam shaft.

(http://i104.photobucket.com/albums/m180/rod_sally/fork4_zpsd58e352e.jpg)

And the hole drilled for the cam follower pivot.  It was easiest to mount the drill in the collet chuck - although a metric drill, at 3.1mm a 1/8" collet gave a better fit than 4-3mm.

(http://i104.photobucket.com/albums/m180/rod_sally/fork5_zps4fbd4933.jpg)

The fork was centred in the 4 jaw independent chuck for drilling and tapping 5BA

(http://i104.photobucket.com/albums/m180/rod_sally/fork6_zps76534cb6.jpg)

The taper for the top sides was calculated at 7 degrees so this was measured using the electronic angle gauge when setting in the milling vice.

(http://i104.photobucket.com/albums/m180/rod_sally/fork7_zps81d26dd3.jpg)



Title: Re: ETW's Wyvern Gas Engine
Post by: swilliams on December 15, 2013, 10:45:37 AM
Nice job on the fork Rod. She's coming together very nicely

Steve
Title: Re: ETW's Wyvern Gas Engine
Post by: sco on December 15, 2013, 12:33:01 PM
Agreed - nice work Rod!

What was the source for the parallels?

Simon.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on December 15, 2013, 03:04:53 PM
Thank guys.  I got the parallels from Arceurotrade but I saw them on the RDG stand at Sandown yesterday, though they weren't wrapped in such pretty pink paper.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on December 15, 2013, 03:10:31 PM
I thought the paper was white but its the red chicken fat they coat them in that turns the paper pink ;)

I got a similar set from MSC/J&L a while back
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on December 15, 2013, 09:10:11 PM
Wow, great work. It is a fantastic looking engine.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on December 19, 2013, 09:06:30 PM
Cheers, Nick.

The last couple of sessions have been spent setting up the valve gear.  I turned some spacers to centre the ball  race cam followers on the cams.  Interesting that since I've been using an indexable parting tool in the back toolpost, I've now got total confidence in parting off from the front, although I think that using the Worden grinder to sharpen the blade helps.

(http://i104.photobucket.com/albums/m180/rod_sally/vg1_zpsecd11b52.jpg)

I finished making the fork and the push rod.  There's plenty of adjustment here on the inlet valve.  The exhaust valve can only be adjusted by the eccentric in the centre of the rocker arm.  I had to shorten the valve stem to bring everything into range.  The cams need a little more attention before case hardening and polishing and there will be a bit more beautifying to do.  The cams aren't yet set on the shaft, the engine needs to be timed to do that.

(http://i104.photobucket.com/albums/m180/rod_sally/vg3_zps16a30470.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/vg2_zpsd1dba0ba.jpg)

Next job - piston rings.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on December 22, 2013, 03:43:15 PM
The piston rings are cast iron.  This lump was  turned and bored to give an OD with a snug sliding fit in the cylinder bore and a wall thickness of 1/16", giving a square section ring

(http://i104.photobucket.com/albums/m180/rod_sally/ring1_zps60a62ce1.jpg)

I parted off 5 rings at 63 thou each according to the topslide dial

(http://i104.photobucket.com/albums/m180/rod_sally/ring2_zps5ef2bec2.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/ring3_zps1844841e.jpg)

The rings were split by holding in the vice and giving a twisting action to the pliers. On the first ring I thought I felt the ring break but on removing from the vice I couldn't find the break, it still felt solid. so I replaced in the vice and repeated the procedure.  On removal it fell into 2 pieces >:(.  One down 4 to go.  The others broke OK and I cleaned up the gap with some SiC paper.

(http://i104.photobucket.com/albums/m180/rod_sally/ring4_zps14cdcebe.jpg)

I placed a scrap 1/16" steel in the gap and heated up to red heat.  The lump of steel was then placed on top to keep the ring flat while it cooled.

(http://i104.photobucket.com/albums/m180/rod_sally/ring5_zps26ce2d46.jpg)

The rings were then cleaned up on the SiC paper.

(http://i104.photobucket.com/albums/m180/rod_sally/ring6_zps05a3d476.jpg)

2 rings ready for installation.

(http://i104.photobucket.com/albums/m180/rod_sally/ring7_zps46d4bb95.jpg)

One job I need to do before installing the rings was to clean up the gap  for the little end of the con rod between the bosses on the inside of the piston.  I've got a Myford nose that screws into my rotary table which allows a chuck to be mounted.  This arrangement rapidly runs out of head room and I had to mount the endmill into a Myford collet rather than my preferred ER25 chuck.  The piston alloy machines easily so all went well.

(http://i104.photobucket.com/albums/m180/rod_sally/ring8_zps2a8c13aa.jpg)

The rings went on pretty easily, I am always surprised how much you can bend them.  This is the third ringed piston I've made and I have yet to break a ring on installation.  Rings fitted and 2 spares, not heat treated - you can just see the break on the left hand one  :)


(http://i104.photobucket.com/albums/m180/rod_sally/ring9_zps6e6623c8.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on December 22, 2013, 03:51:26 PM
 :ThumbsUp: I have never managed to break rings using pliers, I never seem to be strong enough  :(

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on December 22, 2013, 05:48:54 PM
Jo,

It didn't take much effort to break the ring, it's all in the wrist action  8).  Perhaps a Mole type wrench would help you get a good grip on the ring.

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 01, 2014, 11:39:07 AM
A couple of little jobs need doing.  The gudgeon pin is made from a length of silver steel, drilled through.   A pair of brass end caps stop it gouging the bore.

(http://i104.photobucket.com/albums/m180/rod_sally/chd1_zps2d841c66.jpg)

I'm happy that no more serious work needs to be done to the cylinder head so I can get rid of the chucking piece and tap for the plug.  The head was therefore held in a collet  and drilled through at tapping size.  I'm normally happy with about 65% engagement but this cast ally is pretty soft so I used a 8.9 mm drill rather than the recommended 9.0 for the 10x1.5mm plug thread.

(http://i104.photobucket.com/albums/m180/rod_sally/chd2_zpsa4b7dd7a.jpg)

The stub was then milled down to length

(http://i104.photobucket.com/albums/m180/rod_sally/chd3_zps9a4ea6b8.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/chd4_zps876ca5ec.jpg)


Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 01, 2014, 12:45:27 PM
In the first instance I've decided to keep the ignition and carburation as simple as possible.  I've had a coil and some tungsten points waiting around for ever for me to modify an aero engine so I'm going to use those, with petrol as fuel.

The points are mounted on a bracket with a simple cam on the side shaft.

(http://i104.photobucket.com/albums/m180/rod_sally/i1a_zpsa7dbb539.jpg)

A casting is supplied

(http://i104.photobucket.com/albums/m180/rod_sally/i2_zpsa4d4bcd0.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/i3_zps4c7d795c.jpg)

Something of a challenge to hold and my first thought was to ditch the casting and fabricate it out of brass.  We'll see how it goes.

I managed to mill some flats to give me something to hold properly in the vice

(http://i104.photobucket.com/albums/m180/rod_sally/i4_zps84b9da13.jpg)

Then drill some pilot holes

(http://i104.photobucket.com/albums/m180/rod_sally/i5_zps02f00b38.jpg)

The hole for the clamp was spotted then drilled through with reference to the hole for the plunger and then clearance for the cam was made with a 1/2" end mill

(http://i104.photobucket.com/albums/m180/rod_sally/i6_zps83c35bcf.jpg)

The clamp was drilled for 6BA tapping and then slit with a saw

(http://i104.photobucket.com/albums/m180/rod_sally/i7_zps5ccf1e1b.jpg)

Mounting the job in the four jaw in in order to machine the handle was something of a challenge if I wasn't to end up with a pin but I got there with some tentative trial and error cuts.

(http://i104.photobucket.com/albums/m180/rod_sally/i8_zpsef37db9c.jpg)

It's functional at the moment.  I'm really undecided how to finish these part machined castings - whether I should finish all over or (following Jason's example) try to texture the bits I've had to machine to match the as cast surface (which in some cases is pretty horrible anyway).  That's for the future.  My concern at present is to see if I can make it go.

(http://i104.photobucket.com/albums/m180/rod_sally/i9_zps632e5d2b.jpg)




Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 02, 2014, 04:57:21 PM
Rather than the specified spring steel I used Beryllium Copper for the contact breaker.  I bought a selection of strips from the surplus market some years ago (Whiston if anybody remembers his cat  :)  ). In the softened state it's much easier to deal with than spring steel but some people are frightened off by the word beryllium even though BC is widely used in all sorts of domestic switch gear.  I cut the profile out with tin snips and filed to shape before drilling the holes.

(http://i104.photobucket.com/albums/m180/rod_sally/cb1_zpsd55b7c91.jpg)

and making the bend

(http://i104.photobucket.com/albums/m180/rod_sally/cb2_zps18843010.jpg)

In order to get the spring properties the BC needs to be precipitation hardened at 300-350C.  Yonks ago I made a small tempering oven and was quite surprised to find that it still works.

(http://i104.photobucket.com/albums/m180/rod_sally/cb3_zpsf0aa0a17.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/cb4_zpsed16f02d.jpg)

After 2 hours at around 320C (I only have a power controller on the oven so constant tweaking was used to keep the temperature in the right band) the spring was, er, springy.  The insulating washers and actuator were turned up from some 3/8" SRBP sheet.

(http://i104.photobucket.com/albums/m180/rod_sally/cb5_zps6f8bfb32.jpg)

Assembled

(http://i104.photobucket.com/albums/m180/rod_sally/cb6_zps3e8183ec.jpg)

If you have been, thanks for looking.

Rod

Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on January 02, 2014, 05:06:13 PM
Beryllium Copper  :thinking: I didn't know it could be heat treated like that  :ThumbsUp:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 02, 2014, 05:21:19 PM
ME Sep 1990 (3880), written under a pseudonym, explains all.  Much of the practical stuff is outdated since temperature indicators, controllers and even small furnaces are now available cheaply on e-bay.
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on January 02, 2014, 08:09:59 PM
Beryllium Copper  :thinking: I didn't know it could be heat treated like that  :ThumbsUp:

Jo
I am around this stuff all the time being in the Electrical and Electronic field and I didn't know that. Thanks Rod for showing this. You contacts came out great. Did I get you right, you used tungsten for the contact?

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 02, 2014, 08:36:24 PM
Don,

The points are tungsten.  They were  bought as shown on the un-assembled photo about 20 years ago.  The small one is rivetted to the spring and the screwed one is 6BA.  Tungsten discs for brazing onto fittings are available form Hemingway.

cheers,
Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on January 02, 2014, 09:13:08 PM
Still following along Rod.  I guess you will have it running soon.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on January 02, 2014, 09:22:48 PM
Speaking of getting it running  :whoohoo: .. You will find the drawings for the demand regulator (assuming you want to run it on gas) are here: http://www.floridaame.org/Plans/propane_demand_regulator.pdf

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 02, 2014, 11:37:11 PM
Jo,

Thanks for that, I've dowloaded the PDF.  Judging by the trouble that some people are having in getting their engines to go I've decided to keep it as simple and plain vanilla as possible so in the first instance its points, petrol and that rather oversize commercial plug.  No doubt I'll be asking for help before long.  Got to make the carb first though.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on January 07, 2014, 09:53:59 PM
I was under the impression BC was a carcinogen but don't know to what extent, apparently best not to come into contact with skin.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 07, 2014, 10:47:29 PM
Ive been waiting for this post.  Beryllium is a slightly nasty metal.  Beryllia (beryllium oxide) is indeed nasty stuff and causes diseases similar to silicosis and asbestosis.  In beryllium copper the beryllium (about 3%) is locked into the copper metal as a solid solution or as a precipitate at the atomic level.  The chances of the beryllium atoms escaping during normal processing in the model engineers shop are, in my opinion, negligible.  I am quite happy to use it with normal hygiene precautions as I would be using lead solder or cadmium silver brazing alloy, antimony in bearing metals, vanadium in tool steels or zinc in aluminium alloys.

Health and safety data tends to be aimed at the production environment where the potential to exposure is many orders of magnitude greater than that in my workshop.  The thing is to make sure that you understand the hazards because people tend to think they are in control of stuff they can see, such as a milling machine or a lathe, but get frightened by stuff they can't, like toxic dust or radioactivity.  In my view, the hazards of the former are much greater than the latter.

As an individual it's your call. 

Just my view.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on January 08, 2014, 12:53:00 AM
I'm with you Rod,

I have made a number of smallish BC parts and have never been overly concerned. I certainly don't take it to the belt sander and breath the dust though. I need to make the spark saver contacts for my Pacific engine and BC will be my choice for that; also easy to heat treat and make it nice and springy.

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on January 08, 2014, 07:08:03 PM
Thanks for the info Rod, makes sense have come across materials like that in the workplace too and people once people perceive a problem it's hard to change their mind! Just thought I'd say why some people are frightened off by it. I know it was used in one of our products at one time but had
To be changed for something else. There are things like this all over though but as you said it's knowing
What the real hazard is and how to mitigate the risk if there is any!
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 08, 2014, 08:41:57 PM
Nick,

Please forgive me if my reply above above was a little terse.  I spent what felt like my whole career arguing with safety "professionals" who knew a great deal less about the materials that I worked with than I did and who did not understand the difference between hazard and risk.  One of the joys of retirement is that I can make own, informed, decisions about what I can and can't do.

best wishes,
Rod
Title: ETW's Wyvern Gas Engine
Post by: NickG on January 09, 2014, 07:45:10 PM
Not at all Rod, nothing to forgive - it can be an emotive subject, one person in out office resigned over such a situation because he had a differing opinion, had he stayed he would probably have been given a huge redundancy package by now but his feelings
Must have been so strong at the time it made him do that. I felt he was one of those that had been told there was a hazard and swept along in the commotion but didn't stop to think long enough to realise the risk was negligible!
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 14, 2014, 11:15:52 AM
The last major component is the carburettor.  The carb body is in two parts with a rotating barrel inside and a lift valve to control the air intake.  It's a dual fuel carb so there are 2 jets/valves to control the mixtures.  I spent a long time looking at this drawing before I understood what was actually going on  :headscratch:

(http://i104.photobucket.com/albums/m180/rod_sally/carb6_zps3cf66a10.jpg)

 A GM casting is supplied.

(http://i104.photobucket.com/albums/m180/rod_sally/cara1_zpsf6bd879f.jpg)

Seeing as a large chucking piece has been provided at each end the logical thing seemed to be to turn one end to 3/8" so that it could then be turned end for end and mounted in a collet chuck to turn the other end.  This way I have a datum at the axis of the carb.

(http://i104.photobucket.com/albums/m180/rod_sally/cara2_zpsccc22987.jpg)

Once again you can see that registration of the two halves of the casting isn't great.

(http://i104.photobucket.com/albums/m180/rod_sally/cara3_zps53bbdb85.jpg)

Before splitting the casting I drilled through the bosses that will allow the assembly to be bolted together.

(http://i104.photobucket.com/albums/m180/rod_sally/cara4_zpsb2a42d8f.jpg)

The main part of the carb body has a flange that is bolted to the cylinder head.  First the cavity for the barrel was turned and the whole thing drilled all through at 1/16" for the lift valve spindle.  I then transferred to the dividing head on the mill, which has the DRO zeroed at the axis, drilled the flange through to the cavity and milled the mating surface.

(http://i104.photobucket.com/albums/m180/rod_sally/cara5_zps242f7fb8.jpg)

The barrel was a straight forward piece of brass turning.  I drilled and turned the cavity before flattening the base with an end mill.

(http://i104.photobucket.com/albums/m180/rod_sally/cara6_zps9f8b47d5.jpg)

and milled the cross hole in the milling machine

(http://i104.photobucket.com/albums/m180/rod_sally/cara7_zpse44f8c37.jpg)

The lower part of the throttle (valve housing) was part turned and then I milled the flats and drilled the tapping holes for the fuel valves.

(http://i104.photobucket.com/albums/m180/rod_sally/cara8_zpsf2540232.jpg)

I then cut the three air inlet holes.  But something is not right with the valve holes  :o  A bit of misalignment shouldn't be a problem

(http://i104.photobucket.com/albums/m180/rod_sally/cara9_zps9b0dcec6.jpg)

The valve seat is at 45 degrees and the fuel passages are drilled through this into the valve cavity. Drilling these was a bit of a poser   :thinking:  In the end I set up the vertical slide as shown

(http://i104.photobucket.com/albums/m180/rod_sally/carb2_zps8e9c0228.jpg)

Where to actually start the hole was also something of a problem.  My solution was to set the drill above the valve hole so that I could eyeball the position on drilling through and then withdraw and lower the drill to centre height

(http://i104.photobucket.com/albums/m180/rod_sally/carb3_zps8fc8b9e5.jpg)

Withe fuel holes drilled the valve holes needed to be threaded 5/32" x 40 so I aligned the casting in the pillar tool using the tapping drill

(http://i104.photobucket.com/albums/m180/rod_sally/carb4_zps6d6e7116.jpg)

and wound the tap in.  Oh dear........

(http://i104.photobucket.com/albums/m180/rod_sally/carb5_zps71d6862c.jpg)

Somewhere or another I've lost my datum(s).  Oh well, I've got a bit of brass I can make another from.  I think I'll draw it up myself first to check the dimensions and to work out some co-ordinates for drilling those fuel holes.  With a bit of luck it will turn out a bit neater than the casting.







Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on January 14, 2014, 11:52:38 AM
Mechanically that looks like a scaled down version of the carb fitted to my Centaur. Except that the Centaur one is single fuel.

I haven't got any photo's of the carb on mine.. for some reason I think it is done  :noidea: This is the carb on someone elses centaur.

Edit: found a drawing of carb..

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 14, 2014, 01:03:32 PM
Jo, that's interesting, thanks.  Looks like a combined inlet/exhaust manifold.  The inlet valve looks pretty much the same as well.

cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: gbritnell on January 14, 2014, 01:56:57 PM
Hi Rod,
Somehow I have missed this build thread up till now. For that I'm sorry as your work, photos and documentation are first rate. I have gone back to the beginning and read all the posts to get caught up. I especially like how you cut your helical gears as I had to make some for my current project.
I'll be paying attention to the continuation of your build.
gbritnell
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 14, 2014, 02:21:08 PM
Aw... shucks.... :embarassed:

Thanks for the confidence boost

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on January 14, 2014, 06:38:47 PM
Just had a look at mine .. a few photos of the carb bits.

The lift valve floats in the centre of the throttle as it moves it uncovers over the hole in the bottom of the "chamber" which lets the fuel in and there are big two holes further down in the casting that let the air in immediately under the lift valve.

And the throttle itself is a piece of tube with a hole in the side, which pivots in the cap.

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 14, 2014, 07:39:53 PM
Jo,

Basically the same.  Very kind of you to trouble to take the pics.  The Wyvern carb does not use a spring - gravity is supposed to be sufficient.


(http://i104.photobucket.com/albums/m180/rod_sally/wyvernvalvehousing_zpsdfefeb85.jpg)

I've re-drawn the bottom bit to check the dimensions - all seems OK.  I had misread the spacing of the valve guides as 15/32" instead of a 1/2" which (mostly) explains the breakthrough.  I've added the bits in red to be machining aids.  If I add an extra 1/16" to the height and then slot drill  1/8" diameter by 1/16" deep that gives me a"corner" from which to start to drill the fuel passage.  Drilling 17/64" deep should break through nicely into the valve guide passage.  Boring the extra out to 15/32" will then give me a good steer on the taper for the lift valve seat - just turn away until the step disappears.

The practical proof will have to wait - driving to the rainy Alps tomorrow  :)

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Roger B on January 15, 2014, 07:49:17 AM
Quite snowy in the Alps yesterday, even down at our level (600m).
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on January 29, 2014, 11:22:45 PM
Sometimes, things will just not go right   >:(  .  Perhaps there is something in the Hampshire air at the moment.  So, I needed to make a new bottom piece for the carb.  First part off a length of 1" brass.

(http://i104.photobucket.com/albums/m180/rod_sally/rw1_zpsf81b7236.jpg)

Then drill 1/4" deep and turn the register to fit the top half of of the carb.  So why did I drill 1/2" for the one on the left and turn the register too small on the other  :shrug: 

(http://i104.photobucket.com/albums/m180/rod_sally/rw2_zps889beae0.jpg)

 Hey ho, third time lucky.

(http://i104.photobucket.com/albums/m180/rod_sally/rw3_zps515839ed.jpg)

Fuel passages drilled in the right place and the seat for the air regulator turned in.

(http://i104.photobucket.com/albums/m180/rod_sally/rw4_zps607f2e0c.jpg)

Now drill 1/16" through,  Why didn't I centre drill this first?  No idea.

(http://i104.photobucket.com/albums/m180/rod_sally/rw5_zpsd68c961a.jpg)

OK I can fix this.  First, carry on with the rest of the job and mill the air intake holes, 3 around the circumference.  Having centred the axis of the carb in the four jaw, getting a milling chuck close to the 4 jaw was an issue and the 4 jaw won't fit on the dividing head in the mill if there is any projection from the screws.  Ended up with this that worked fine.  That's an ER11 chuck with a small JT taper on a 1mt taper in the milling spindle holding a 5mm slot drill (rather than 3/16" because the 3/16 was too short and the ER collet fouled the 4 jaw

(http://i104.photobucket.com/albums/m180/rod_sally/rw6_zps9d7cd8d9.jpg)

Now turn off the spigot with the offending hole.

(http://i104.photobucket.com/albums/m180/rod_sally/rw7_zps6dddbaf3.jpg)

and turn a plug to fit

(http://i104.photobucket.com/albums/m180/rod_sally/rw8_zps8e48c960.jpg)

This was then soft soldered in place.  I didn't use Loctite because I was impatient to get on with it (which may be why all these problems are happening  :thinking: )

(http://i104.photobucket.com/albums/m180/rod_sally/rw9_zps34496249.jpg)

The plug was then turned and drilled through

(http://i104.photobucket.com/albums/m180/rod_sally/rw9a_zps0511822b.jpg)

I now need to spot through for the screws to hold the 2 bits together and do some file work to blend the new bit with the lugs on the casting.

(http://i104.photobucket.com/albums/m180/rod_sally/rw9b_zpsd24aef90.jpg)

Rod  (smiling again now)

oh, and the snow was fine   :)
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on January 30, 2014, 01:40:13 AM
Rod I know how those days can get frustrating. Some days it pays to go home and just relax. But hey you did OK looking at you work.

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: Bezalel on January 30, 2014, 01:43:42 AM
Nice save Rod   :ThumbsUp:
 
 
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on January 30, 2014, 07:36:06 AM
It is nearly February so hopefully this Hampshire "air" will clear and we will all have better luck in the workshop. Seeing you making the last few bits is making me think about my Centaur again  :facepalm:

I can't interest you in a 1/4 scale Otto Langen build can I  :naughty:  (Can't have you running out of engines to build   :mischief:)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Ramon Wilson on January 30, 2014, 07:58:51 AM
Third time lucky eh Rod? I know that feeling only too well  ::) Nice reclamation work though - keep it up  :ThumbsUp:

Regards - Ramon
Title: Re: ETW's Wyvern Gas Engine
Post by: steamer on January 30, 2014, 09:04:44 AM
Only 3 times!... 8)    I usually make more tries than that....Goodonya Rod.   Nice save.

Like that little dividing head and tool post mill spindle....feel free to post pictures of those to a thread in the tool section! :ThumbsUp:

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on February 10, 2014, 03:17:23 PM
Thanks guys, nice to know it's not just me.  The fuel control system is straightforward, if fiddly, brass turning.

(http://i104.photobucket.com/albums/m180/rod_sally/jet1_zpsb347ba66.jpg)

This is threaded 5/32" x 40.  I made up a 3/8" precision ground mild steel stub with the 5/32 thread in it with the idea that I could return it to the collet and ensure it was co-axial any time I needed to use it again.  Sadly, after I used it I tried to punch the size onto it but it flew out of my hand and the little man who lives under the bench grabbed it, never to be seen again  :(

(http://i104.photobucket.com/albums/m180/rod_sally/jet2_zps1a819238.jpg)

After threading the other end I drilled through for the required jet size

(http://i104.photobucket.com/albums/m180/rod_sally/jet4_zps732ca392.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/jet3_zps2039b8ad.jpg)

The needles are brass as well.  I knurled the finger grip first.  My knurling tool is too large to fit into the QCTP so it lives in the Gibralter toolspost

(http://i104.photobucket.com/albums/m180/rod_sally/jet5_zps03b53aad.jpg)

The rest was straightforward turning, though I was pleased at the way the lathe handled the 15 degree taper

(http://i104.photobucket.com/albums/m180/rod_sally/jet6_zpsa165f5bf.jpg)

The lift valve controls the air input.

(http://i104.photobucket.com/albums/m180/rod_sally/jet7_zps6a77085d.jpg)

This needs to be pressed onto a 1/16" steel shaft.  A test showed it was loose on a 1.6mm  drilled hole so the only alternative was 1.5 mm.  I held the shaft in the 3 jaw and used the tailstock to push the valve onto the shaft.  I could only get it to go on an 1/8" so tried gently heating the valve with a fine cook's torch.  This worked a treat.

(http://i104.photobucket.com/albums/m180/rod_sally/jet8_zps5fe91d09.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/jet9_zps16c4ee03.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/jet91_zpse263d40a.jpg)






Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 05, 2014, 01:57:19 PM
I've been doing some housekeeping in the workshop recently with some new tools in and others out (not all ME orientated).  However, now it's back to the Wyvern:

The throttle lever as drawn looks more suitable for a r/c aircraft than a stationary engine

(http://i104.photobucket.com/albums/m180/rod_sally/ca1_zps54b20245.jpg)

so I branched out with my own design  :o

(http://i104.photobucket.com/albums/m180/rod_sally/ca2_zps0ca8a7d7.jpg)

The cast upper body of the carb has become somewhat awkward to mount on the cylinder head.  The right angled inlet hole is lined up nicely with the carb axis but sadly the flange pipe exterior is offset from this line.  The stud holes in the flange have to go where they can be fitted to allow the nuts to turn.  I then made a short spigot that has one end 5/16" diameter to match the cylinder head inlet and reduced to 1/4" to match the carb. (Do you get the impression that ETW used an existing carb off an aircraft engine?)  The body of the carb would interfere with a normal transfer punch so I made a short one.

(http://i104.photobucket.com/albums/m180/rod_sally/ca3_zpsaab83842.jpg)

This rather Heath Robinson affair was the resulting assembly.  The G clamp is holding the carb in place, located by the spigot and at right angles according to the set square.  The toolmakers clamp was used to squeeze the transfer punch to provide the centre spot for drilling.

(http://i104.photobucket.com/albums/m180/rod_sally/ca4_zps4eea38c0.jpg)

One of the recent workshop mods was to fit adjustable feet to the milling machine stand and level it up with respect to the rest of the world.

(http://i104.photobucket.com/albums/m180/rod_sally/ca5_zps47ea4560.jpg)

Then, as recommended by Jo, I used the spirit level to set up the cylinder head and drill the 6BA stud holes.  :)

(http://i104.photobucket.com/albums/m180/rod_sally/ca6_zps305198c7.jpg)

This is the carburettor fully assembled.  I'm still worried about how to finish the semi filed lumpy castings - possibly thick paint will be the answer.  I'd also thought that, for testing purposes, I could have an open exhaust but that would be blowing straight into the air inlet.  I can feel some silver soldering coming on.

(http://i104.photobucket.com/albums/m180/rod_sally/ca7_zps06f9148d.jpg)

Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on March 05, 2014, 02:18:33 PM
That is a much nicer throttle lever  :ThumbsUp:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: zeeprogrammer on March 05, 2014, 06:02:07 PM
My apologies for missing your thread Rod. I just went through it from the beginning.
Looks like I had dropped in once before but had forgotten.  :old:
Really good thread. Loads of pictures and details...not to mention a really interesting engine.
Looking forward to the run.
Title: Re: ETW's Wyvern Gas Engine
Post by: Roger B on March 05, 2014, 07:40:59 PM
As ever some good looking work  :ThumbsUp: :ThumbsUp:

Looking forward to the running video and possibly the happy dance  ;)
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on March 05, 2014, 10:15:21 PM
Rod glad to see you picking back up on the thread. I am so looking forward to seeing it completed and running. Some nice work going on here for sure. I like........... :praise2:

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 05, 2014, 10:56:09 PM
Thanks for maintaining an interest guys.  There's a bit of fiddleing around to do yet:  I need to at least drill some oil holes if not make the oilers and there is a bit more stud making to do.  I'll also need to sort out a temporary fuel supply and delivery pipework.  The cams need timing and mounting.  But we are close to trying to make it run  :o

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Tennessee Whiskey on March 05, 2014, 11:42:24 PM
Great looking work Rod. Now just get the Mrs. to knock up some of those pancakes and keep on keeping on :cheers:

Whiskey
Title: Re: ETW's Wyvern Gas Engine
Post by: b.lindsey on March 06, 2014, 12:57:52 AM
Nice progress and great pictures Rod. Nice to see an update on this one.

Bill
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 07, 2014, 08:46:25 PM
Apart from some studs today, I've also needed to make some flanges for the cooling water input/output and the exhaust.  I decide to make these all the same and slice them off.

(http://i104.photobucket.com/albums/m180/rod_sally/f1_zps192bd686.jpg)

The end on view shows a 7/8" brass bar.  The flanges are 3/4" across the widest bits with a 1/8" radius at the "points".  Drawing them out gave an angle connecting the tangents of 24 degrees which was fortuitous since this is 4 turns of my dividing head.  Having turned the OD I drilled the centre hole and then the clearance holes for 6BA using the milling spindle.  This is now easy to set up.  Having a non adjustable dial on the vertical slide is an advantage here since I know that when the dial reads 65 it is on centre height (or 0.1" above or below!)

(http://i104.photobucket.com/albums/m180/rod_sally/f2_zpse9c834f6.jpg)

Transferring the chuck to the dividing head in the mill I set the holes to vertical by winding the dividing handle and then put the sector arms either side of the plunger.

(http://i104.photobucket.com/albums/m180/rod_sally/f4_zps1ffed135.jpg)

It was now just a case of counting whole turns to rotate the job to the required angle for milling

(http://i104.photobucket.com/albums/m180/rod_sally/f5_zps965f084e.jpg)

They were parted off in the lathe (slightly alarming, the start of the cut sounded like a helicopter was landing on the roof   :o ).  I also turned the stub on the embryo exhaust.  The acute angles were rounded with 1/4" diameter filing buttons and the obtuse angle was just blended free hand.  The water connections will be soft soldered to some copper pipe.  The exhaust will be silver soldered to an elbow, still thinking how best to make that  :thinking:

(http://i104.photobucket.com/albums/m180/rod_sally/f6_zpse359c3a3.jpg)

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on March 07, 2014, 11:59:09 PM
Rod that was a nice piece of work and I like your milling attachment. Mine is for drilling and I guess I could do some milling with small end mills with it. I will need to give it a try. How ever it was originally a tool post grinder and the motor does turns 6000 RPM.

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 10, 2014, 02:39:07 PM
Don,

Thanks, I can use a 1/4" endmill in steel with mine, runs at about 2500 rpm.
 
The elbow:  I decided to hack it out of a length of 5/8" brass rod.  I shall need to be pretty accurate on the drill depths.

(http://i104.photobucket.com/albums/m180/rod_sally/elbow1_zps7d77a317.jpg)

I turned the exhaust stub first in my nice  new (to me) little 4 jaw independent

(http://i104.photobucket.com/albums/m180/rod_sally/elbow2_zps1293940f.jpg)

The depth of the holes were carefully controlled using the scale on the tailstock

(http://i104.photobucket.com/albums/m180/rod_sally/ts4_zps4aa76fc8.jpg)

Then milled of most of the surplus using the dividing head as a horizontal rotary table

(http://i104.photobucket.com/albums/m180/rod_sally/elbow3_zps8d9deb0c.jpg)

Then back to the lathe to drill the hole at right angles and as much of the exterior of the stub as I could

(http://i104.photobucket.com/albums/m180/rod_sally/elbow4_zpsa80398da.jpg)

I turned up a mandrel with a slight taper and finished off the shaping with files

(http://i104.photobucket.com/albums/m180/rod_sally/elbow5_zps9d4db196.jpg)

The flange is an easy fit in the stub and I also countersunk it to provide some space for the silver solder.  I wound up a ring of easyflo and fluxed all the mating parts

(http://i104.photobucket.com/albums/m180/rod_sally/elbow6_zps6a45b39d.jpg)

A brief heat with a pseudo MAPP torch trying to avoid direct  flame on the solder and this was the result.

(http://i104.photobucket.com/albums/m180/rod_sally/elbow7_zps955b9fd6.jpg)

After cleaning up with  files and emery (I haven't got a pickle bath on the go at the moment), this will do

(http://i104.photobucket.com/albums/m180/rod_sally/elbow8_zps854359a3.jpg)
Title: Re: ETW's Wyvern Gas Engine
Post by: zeeprogrammer on March 10, 2014, 03:55:00 PM
That came out beautiful. Nice job.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 12, 2014, 02:07:03 PM
Thanks Zee.  Unfortunately the stub coming out of the flange is too long  :-[  . Had to cut it off, shorten and re-do. Don't know what happened there but it's OK now.

Almost ready to start assembly.  The cams are supposed to be pinned to the shaft but in order to give me some adjustability I've decided to  use a pair of 2mm socket grub screws in each cam so I opened out the existing hole and drilled a second one at right angles.  If the 2 screws are inadequate I can always pin through after I've got the timing sorted.  I used the small tapping head in the UPT for this job.

(http://i104.photobucket.com/albums/m180/rod_sally/hcam1_zpsb85ca1ca.jpg)

The cams also need to be case hardened.  The cams were held on a length of steel for ease of handling.  They were heated to bright red with a gas torch and then rolled in the tray of Kasenite.  I repeated this a couple of times to get a good adherent coat.  Then heated for about a minute more and quenched in the jam jar of water

(http://i104.photobucket.com/albums/m180/rod_sally/hcam2_zpsc35ac570.jpg)

Here they are after quenching

(http://i104.photobucket.com/albums/m180/rod_sally/hcam3_zps8d4e3650.jpg)

And then after a bit of cleaning up using fine emery

(http://i104.photobucket.com/albums/m180/rod_sally/hcam4_zps4d25ee87.jpg)

The surface seems hard, a file skids off.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 25, 2014, 08:30:38 PM
Assembly is proceeding with some bits of fitting:

The main bearings need to have the oil holes drilled through.  Because the hole in the cap is not over the centre of the crankshaft I used a slot drill to make the hole and a subsequent slot in the bearing.  No need to make the oilers yet, there is a big enough well for testing.

(http://i104.photobucket.com/albums/m180/rod_sally/fit1_zpsa9cd5e8c.jpg)

I used a cheese head screw to lock the bearings in position to ensure that they don't rotate and cause the oil passages to become misaligned.  I milled a crescent out of the bearing to match the screw head diameter

(http://i104.photobucket.com/albums/m180/rod_sally/fit2_zps80ec7fbc.jpg)

The big end bearing will need lubrication so I had to make the oiler for this.  A bronze casting was supplied but I preferred to fabricate using soft soldered brass.  The screwed pipe passes through the bearing to ensure that it does not rotate either.

(http://i104.photobucket.com/albums/m180/rod_sally/fit3_zps91ca902f.jpg)

I had neglected to make the ignition cam.  This is essentially just a flat though ETW recommends making it with a slight curve to control the acceleration a little so I made it with a bit of eccentric turning.  This is supposed to be case hardened but as the follower is a piece of SRBP rod I'm not sure this is necessary.

(http://i104.photobucket.com/albums/m180/rod_sally/fit4_zps18a1f295.jpg)

Rather than being pinned, the cam is positioned, like the valve cams, using M2 grub screws

(http://i104.photobucket.com/albums/m180/rod_sally/fit5_zps04f956c1.jpg)

This is beginning to get serious.  I went to the local mower/chainsaw place today to buy some fuel pipe and some Aspen alkylate petrol  :o
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on March 25, 2014, 08:40:37 PM
Nice work Rod.  Looking forward to see it come to life.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: fumopuc on March 26, 2014, 05:00:46 AM
Hi Rod, nicely done. I wish you good  luck for your first attempt to get it running.
Title: Re: ETW's Wyvern Gas Engine
Post by: ozzie46 on March 26, 2014, 01:17:20 PM
Very nice work. Hope to hear it run soon.   :ThumbsUp:

 Ron
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on March 26, 2014, 02:51:22 PM
NIcely done Rod and I am so looking forward to launch time.  :ThumbsUp:

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on March 31, 2014, 05:38:27 PM
 :cartwheel:


https://www.youtube.com/watch?v=qNMajVwgDu0

I haven't yet managed to get the ETW carb to work - but it goes OK with the carb that I made for my 10cc Matador glow engine. 

(http://i104.photobucket.com/albums/m180/rod_sally/matcarb_zps3098e1de.jpg)

 :whoohoo:

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on March 31, 2014, 05:48:59 PM
 8)

Another volunteer who is qualified to look at my R&B  :naughty:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on March 31, 2014, 05:55:18 PM
Sweet!

Congratulations on the first pops.


Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Kim on March 31, 2014, 08:34:04 PM
Congrats Rod!  It runs!  :cartwheel:

Thanks for sharing the video.
Kim
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on March 31, 2014, 08:48:46 PM
Congrats Rod on running your Wyvern. Hope you get the original carb to work also.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on March 31, 2014, 09:07:22 PM
Oh wow! She's a runner and a great job Rod. Congrats on a nice build I love it.  :praise2:

Don
Title: Re: ETW's Wyvern Gas Engine
Post by: Stilldrillin on March 31, 2014, 10:21:25 PM
Well Done, Rod!  (http://smileys.on-my-web.com/repository/Respect/respect-061.gif)

David D
Title: Re: ETW's Wyvern Gas Engine
Post by: zeeprogrammer on March 31, 2014, 10:43:21 PM
Congratulations Rod!
I enjoyed it.
Title: Re: ETW's Wyvern Gas Engine
Post by: NickG on April 01, 2014, 09:44:08 PM
What a superb engine Rod! Well done.
Title: Re: ETW's Wyvern Gas Engine
Post by: fumopuc on April 02, 2014, 05:19:03 AM
Hi Rod, congratulation for your first run. I like the sound.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on April 02, 2014, 09:41:09 PM
Guys,

I'd just like to thank everybody for the advice, encouragement and kind words over the course of this build.  There's still a bit to do but the rest is trivia.  I'll post some pictures when it's painted (may be a while).

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: wagnmkr on April 02, 2014, 10:26:14 PM
Ahhhh ... The sweet sound of success :ThumbsUp:

An enjoyable ride and an excellent finish.

Cheers,

Tom
Title: Re: ETW's Wyvern Gas Engine
Post by: Heffalump on April 03, 2014, 08:47:17 AM
Fantastic!!!
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 27, 2014, 11:31:14 PM
Wyvern's been to the beauty parlour prior to display at Guildford next weekend:  Peugeot indigo blue and some simple drip oilers

(http://i104.photobucket.com/albums/m180/rod_sally/glam1lr_zpsb1f229d7.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/glam2lr_zps3468457e.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/glam3lr_zps7dbd4f64.jpg)

(http://i104.photobucket.com/albums/m180/rod_sally/glam4lr_zps8d298076.jpg)

I've added a basic pepper pot type exhaust made out of silver soldered brass and painted with heat resistant black paint - the same as the cylinder head

(http://i104.photobucket.com/albums/m180/rod_sally/glam6_zps9cf699ee.jpg)

and a fuel tank from soft soldered copper pipe which has an adjustable height because I'm still not sure about the original carb.

(http://i104.photobucket.com/albums/m180/rod_sally/glam5_zps0b066867.jpg)

The crowned pulley hides a starting dog nut to replace the prop spinner on the running trials.

(http://i104.photobucket.com/albums/m180/rod_sally/glam7_zps86f55552.jpg)

I really didn't know what to do about the cooling tank, this bean can conversion may only be temporary (who am I kidding!)

(http://i104.photobucket.com/albums/m180/rod_sally/glam8_zpsb616de2d.jpg)

The "power box" contains 2 C size Duracells, the coil and condenser for the points

She thinks she's quite glamorous now, but I know what she'll be up against next week  :o

Cheers,

Rod




Title: Re: ETW's Wyvern Gas Engine
Post by: Dave Otto on June 28, 2014, 12:58:20 AM
She sure looks nice Rod!

I'm sure she will make a good impression at the show.

Dave
Title: Re: ETW's Wyvern Gas Engine
Post by: Don1966 on June 28, 2014, 01:03:07 AM
Oh man! Look at that beautiful looking engine. Rod you have out done your self bud. I love that color it just takes your breath away and makes the engine really stand out. Great job I like............ :praise2:


Don
Title: Re: ETW's Wyvern Gas Engine
Post by: vcutajar on June 28, 2014, 05:06:57 AM
That is gorgeous.  It looks totally different.

Vince
Title: Re: ETW's Wyvern Gas Engine
Post by: fumopuc on June 28, 2014, 06:20:37 AM
Hi Rod, she is a beauty. The colour is perfect. Have a good show.
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on June 28, 2014, 08:29:29 AM
That looks good  :ThumbsUp:

She thinks she's quite glamorous now, but I know what she'll be up against next week  :o

Rod, you have to remember some model makers do similar things for their living, so they as good as practise everyday so it would be embarrassing for them if their paint work was not head and shoulders above the rest of us. Us mortals avoid painting our models and if we are really lucky they run  ;D
 
It would be like comparing my models with my friend Lenny Steel's loco :paranoia:. Lenny is one of the best machinists I have ever met, which means he wants to get everything just right, even down to having the raised water flow arrows on the injector: each of them on the injector are less than 2mm long, 1mm wide and .3mm thick. Each perfectly matches the BR original feathered arrow shape and there is no paint on them to allow for any failures to be hidden :Doh:

The important thing is not who's model is "best" but that we enjoy making our model engines  :whoohoo:

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 28, 2014, 09:15:14 AM
Understood.

But one wouldn't like to let the side down.

After all the stripping down and re-fitting, I'm now going to see if she still goes......

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Roger B on June 28, 2014, 01:18:58 PM
I missed the video of it running first time round. Really good  :ThumbsUp:  :ThumbsUp: The paint job and finishing details are excellent  :praise2:  :praise2: I hope you have no problems getting her running again.
Title: Re: ETW's Wyvern Gas Engine
Post by: Ian S C on June 28, 2014, 01:22:01 PM
Rod, I hadn't seen this part of this thread when I guessed (in the ME site) that your water tank was a bean tin! :ThumbsUp:     Ian S C
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on June 28, 2014, 03:42:28 PM
Well, she does still go, but not with the ETW carb (see my warning about CO).  I'm going to make a simple air bleed carb based on the Matador design - that works fine.

I did wonder about disguising the bean tin but thought that corrugations might be reasonably authentic for the period  8)

Thanks for the kind comments.

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 03, 2014, 09:56:24 PM
Wyvern is now sporting a new carb, hacked out of 7/8" brass bar.  This is a simple spray bar, based on the dimensions of the Matador design.

(http://i104.photobucket.com/albums/m180/rod_sally/newcarb_zps17ef3fdd.jpg)

She runs OK but is very sensitive to the mixture control, the needle just needs to be open about an 1/8 turn.  She would therefore seem to be over rich.  I haven't got an air bleed hole.  The feed and spray holes are both 1mm diameter.  Some R&D is required after the Guildford show.  Any advice would be most welcome.

I've made another video but she's jumping about a bit on the cheap Workmate clone.

[youtube1]https://www.youtube.com/watch?v=WS60rqETM5I[/youtube1]
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on July 03, 2014, 10:02:06 PM
I wish my R&B run like that  :ThumbsUp:

A simple trick that I noticed on Eric's ignition box for running his engines on a workmate is his has a dowel the size of the holes in the top of the workmate in the bottom. Which is poked in one to the holes to hold the ignition firm on the top of the workmate  ;) 

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on July 03, 2014, 10:37:02 PM
I wish my R&B run like that  :ThumbsUp:


She will.
 
Wyvern still needs a good whack from the electric drill to get her going - no flick of the wrist like some of the other Wyvern Youtubes  :(

See you Saturday  :)

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on July 04, 2014, 07:27:54 AM
A longer taper on the needle should give you finer adjustment. One up from that is to have the needle seat into a hole with a matching taper. A lot of the carbs on the hit and miss engines that I have done are very much on/off if built with the quite steep tapers shown.

J
Title: Re: ETW's Wyvern Gas Engine
Post by: RayW on February 11, 2015, 07:20:54 PM
Hi Rod,
I am new to the forum but have been following your progress closely as I have been building a Wyvern, but quite a few steps behind you. Thanks for all the helpful hints and ideas that I have picked up (stolen) along the way. Like you, I had one or two traumas but thrilled to say that the engine actually fired and ran briefly on the very first spin of the flywheel so looks like I did something right. There a still a few details that I want to sort out before getting to the painting stage, but well pleased with progress to date. Have posted a short video of the second run on YouTube.
https://www.youtube.com/watch?v=-3yJFchXy_Y


Ray Wilkinson
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on February 11, 2015, 08:43:32 PM
 :ThumbsUp: :)
Title: Re: ETW's Wyvern Gas Engine
Post by: Themule on September 23, 2015, 11:26:46 PM
Rod - did you come to a conclusion on the carb design in the end? I have come to a point in the build where I am about to start on the carb - not sure whether to follow the original design or not.

Andy
Title: Re: ETW's Wyvern Gas Engine
Post by: RayW on September 24, 2015, 09:22:24 AM
Hi Andy. As you will see from my video, my Wyvern runs well on the carb as per the plans. I made it exactly as shown, with gas and petrol jets, but have only tried it on propane so far with excellent results. If you have any questions about the build please free to ask.
Title: Re: ETW's Wyvern Gas Engine
Post by: tangler on September 24, 2015, 02:15:38 PM
Very pleased to see Ray's engine running so well with the original carb design, albeit on propane.  I really don't know what's wrong with mine (bad workmanship?) but I really must have another go at it.

Ray, are you using a demand valve on your propane feed?

Cheers,

Rod
Title: Re: ETW's Wyvern Gas Engine
Post by: RayW on September 24, 2015, 04:20:21 PM
Hi Rod. No demand valve, just the carb and an adjustable regulator on the gas bottle. Pressure is extremely critical. You only need a whisper of gas and the least bit too high or low and it won't run.
Title: Re: ETW's Wyvern Gas Engine
Post by: Themule on September 28, 2015, 11:08:04 PM
Thanks Ray - Thats good to know. I will crack on with it and see how I get on. Every other part is now made, apart from finding some tungsten disks for the contact breaker and soldering them on and of course timing and fitting. Its the first IC engine I have tried so lets see. Thanks again. Andy
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on September 29, 2015, 07:35:06 AM
You can cut slices of a tungsten TIG electrode with a Dremel slitting disc. OR Hemmingway sell them.

http://www.hemingwaykits.com/acatalog/Ignition.html
Title: Re: ETW's Wyvern Gas Engine
Post by: ThomasB on November 18, 2015, 02:10:56 PM
Hi Rod,
Your build has been the inspiration for me to dust off my Wyvern after about 20 years. Have been working on the main bedplate which only had datums machined, built up the crank and bored the
main bearings. Flywheels luckily I machined previously although they need lots of work on the unmachined surfaces. Am still sorting out what has been done and whether it's OK or not.
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on November 18, 2015, 02:29:48 PM
Hi Thomas,

I happen to know that Rod is in New Zealand at the moment and won't be back for a few weeks. So please don't be dissapointed when he takes a couple of weeks to respond to you  ;)

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on June 02, 2016, 02:43:37 PM
I see Rod's Wyvern has made it onto the front cover of the latest ME, No 4536 :)
Title: Re: ETW's Wyvern Gas Engine
Post by: Themule on February 11, 2017, 09:51:52 AM
Hello Rod - i have nearly completed my Wyvern now. One thing I am unsure of is the oiler that oils the piston skirt. I can't see anything on the plans or the original build instructions from ETW - is it a case of simply having the piston liner inserted into the water jacket and then drilling through both - so oil reaches the piston skirt? Is oil meant to reach the little end from this source as well. Andy
Title: Re: ETW's Wyvern Gas Engine
Post by: Jo on February 11, 2017, 10:47:35 AM
Andy I don't know if Rod is going to be able to reply for a week: He was last seen heading for Heathrow airport to go Skiing  :-\

Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Themule on February 11, 2017, 12:05:34 PM
lucky so and so - thanks Jo
Title: Re: ETW's Wyvern Gas Engine
Post by: Jasonb on February 11, 2017, 01:25:58 PM
Usual practice is to drill down say 1/16" dia through both the main casting and the liner once the liner is in place.

Some engines will have a matching hole on the top of the piston with the intension that some of the oil will find its way down to the wrist pin.

J
Title: Re: ETW's Wyvern Gas Engine
Post by: RayW on February 12, 2017, 09:46:49 PM
Hi Andy.
I have just checked my Wyvern plans. The main body is drilled and tapped 3/16" x 40 TPI for the oiler. If you look at the drawing for the cylinder liner, you will see that it is marked 1/8" hole located in situ, in other words drill once the liner is installed so that it lines up with the threaded oiler hole.
The piston shows a 3/16" hole through the skirt just behind the gudgeon pin. The little end of the connecting rod has a 1/16" countersunk hole on the top to collect oil to lubricate the little end bearing.
Hope that helps but feel free to ask if you need any more help.
Title: Re: ETW's Wyvern Gas Engine
Post by: Themule on February 18, 2017, 09:01:52 PM
Thanks so much guys
Title: Re: ETW's Wyvern Gas Engine
Post by: Themule on February 18, 2017, 09:05:34 PM
After staying at those plans I totally missed both those oil holes  - seems obvious now you have pointed them out  :-*
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