Author Topic: Another Westbury Wyvern build  (Read 4497 times)

Offline deltatango

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Another Westbury Wyvern build
« on: January 01, 2019, 11:38:15 AM »
Hi everyone and I hope you all have a very happy and useful 2019!

Now that Mastiff is running (not really finished, but nothing here ever is) its time to make a start on the next project. It is also the 1st January 2019 which sounds like a good time to start anything.

Making Mastiff generated a lot of swarf and all that metal carving has, at least temporarily, satisfied my need for machining from the solid. This time around I have a set of castings and materials for E. T. Westbury's "Wyvern". Once again I've modelled the engine based on the original Westbury drawings (plus hints from this forum and others) using the Alibre 3D CAD package. With Mastiff I made 2D drawings as and when needed, this time I've created a full set before starting to cut metal. No doubt I'll find out the problems with these as I go along.

Many of you will already know what Wyvern looks like but here it is for those who don't:



The PDF of the GA drawing is at :

https://onedrive.live.com/?authkey=%21AJ%5FpFM1IAFxp8q4&cid=2272D9130B9B6673&id=2272D9130B9B6673%212741&parId=2272D9130B9B6673%212733&o=OneUp

It is too big to attach and I'm not sure just how to add a hyperlink to a file, hope it works. If not I guess someone will put me straight.

The casting set from Hemingway Kits looks like:



Only the flywheels are in CI.

I made a start on machining the sub-base this pm, pictures in the next post.

Regards, David

Edit 2019-03-28: Drawing .pdf and .jpg files updated - see later post DT
« Last Edit: March 28, 2019, 02:22:19 AM by deltatango »

Offline Jo

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Re: Another Westbury Wyvern build
« Reply #1 on: January 01, 2019, 12:00:32 PM »
:thinking: Nice set of castings David. We just checked our set and the flywheels are the only CI parts in that set as well. Our carb is Ali... Have you thought about the skew gears


Looking forward to watching your build.

Jo

P.S. I fixed both links  ;)

« Last Edit: January 27, 2019, 01:53:29 PM by Jo »
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Offline Alyn Foundry

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Re: Another Westbury Wyvern build
« Reply #2 on: January 01, 2019, 01:51:16 PM »
Like these?

 ;)

Offline Jasonb

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Re: Another Westbury Wyvern build
« Reply #3 on: January 01, 2019, 03:04:01 PM »
Ideal if you are going for the "barn find" look :LittleDevil:

Nice job on the drawings though the link does not work for me either. Lookforward to following your build.

Offline Alyn Foundry

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Re: Another Westbury Wyvern build
« Reply #4 on: January 01, 2019, 03:59:29 PM »
Ideal if you are going for the "barn find" look :LittleDevil:


Hi Jason.

The " special " coating isn't just for castings, you know!!   :lolb:

Ten sets were cut for my Hornsby Akroyd quarter scale replica. Half inch crankshaft 5/16" sideshaft.

Offline b.lindsey

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Re: Another Westbury Wyvern build
« Reply #5 on: January 01, 2019, 04:18:13 PM »
David, I think the link is fixed now.

Bill

Offline Jasonb

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Re: Another Westbury Wyvern build
« Reply #6 on: January 01, 2019, 04:20:35 PM »
link works now though it only goes to an image and not a pdf but we have lost the image of the drawing from the post :headscratch:

Offline b.lindsey

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Re: Another Westbury Wyvern build
« Reply #7 on: January 01, 2019, 05:45:58 PM »
I didn't mess with the other link that I know of. Maybe David can edit that one since it worked the first time.

Bill

Offline Jasonb

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Re: Another Westbury Wyvern build
« Reply #8 on: January 01, 2019, 06:31:46 PM »
Both correct now.

Offline Art K

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Re: Another Westbury Wyvern build
« Reply #9 on: January 01, 2019, 11:05:18 PM »
David,
That looks like an interesting project. Must admit to not having built from castings despite having a set of Galloway 1/6 scale.
Art
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Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #10 on: January 01, 2019, 11:49:50 PM »
Hi Jo, Jason and Bill,
Thanks for sorting out the link, I think I now know the format, will find out for sure shortly.

The skew gears I have came without the protective brown coating:



Unlike soggier parts of the globe I can store things and have them stay dry. The downside is the occasional "warmer" day - Friday's forecast is for 42 C.

The first bit of machining was on the sub-base. After filing and using wet-or-dry on the surface plate to flatten off the bottom the casting was brought to height on the mill:



The alloy was horrible to file, even a sharp file filled with chalk picked up and scored the surface, but the AGPT tips on the facing cutter left a really good finish.

The drawing shows the height as 2.75", the casting cleaned up to this with ~0.030 to spare; a warning to check and set up all castings carefully and remove the minimum of metal:



The PDF of the drawing is, I hope, at:

https://1drv.ms/b/s!AnNmmwsT2XIilTCcfiNHmMoajmAv

A 3D PDF (generated by Alibre so it will be free from any nasties) of the whole engine model is at:

https://1drv.ms/b/s!AnNmmwsT2XIilTQ0E39PkE9RAM1T

If anyone wants info on using the 3D PDF format, please let me know and I'll try to help. There is a lot you can do with these (e.g. cut sections).

David

OK, had to edit the URL for the drawing - I'd put in the .jpg in error. DT

Edit 2019-03-28: Drawing .pdf and .jpg file updated - see later post.
« Last Edit: March 28, 2019, 02:23:54 AM by deltatango »

Offline simplyloco

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Re: Another Westbury Wyvern build
« Reply #11 on: January 02, 2019, 12:28:04 AM »

Unlike soggier parts of the globe I can store things and have them stay dry. The downside is the occasional "warmer" day - Friday's forecast is for 42 C.
SNIP
David

I know how you feel. I lived in Doha, Qatar for over a year in the late 80's: 48C during the summer... :hellno:
John

Offline Jasonb

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Re: Another Westbury Wyvern build
« Reply #12 on: January 02, 2019, 07:24:26 AM »
3D file is working OK.

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #13 on: January 02, 2019, 07:50:43 AM »
Thanks for confirming that Jason.
David

Online Dave Otto

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Re: Another Westbury Wyvern build
« Reply #14 on: January 02, 2019, 11:50:10 PM »
Nice work on the CAD model David.
I will be looking forward to following along with your build.

Dave

Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #15 on: January 03, 2019, 11:02:55 AM »
Another interesting build to follow  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #16 on: January 03, 2019, 08:51:32 PM »
Thanks Dave and Roger, it's good to have you along.

Summer may slow down progress for a while (e.g. fishing, beach and the garden) so please be patient!

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #17 on: January 18, 2019, 01:19:46 AM »
Right - back from the beach and into the workshop.

Getting the bed plate squared up and to size looks like it's critical and everyone here tell me that these casting thingies aren't always quite what they should be. A careful check was needed:



Everything looked close to right and had enough (just) metal to get the part out of it, I missed seeing the only bit that was misplaced until later. The datum faces are going to be the underside and two edges of the bottom flange:



which involved a lot of careful clamp-juggling to keep the casting secure and get access for the cutter:



after turning the part over I could machine much more stable clamping surfaces on the top:



which allowed me to drill the securing stud holes - including one in the wrong place and the JBW'd plug is just visible here:



with the casting nested against a parallel clamped to the angle plate (it all has to be this way 'round to get the Y-axis travel needed, must look at a more flexible clamping system sometime) the cylinder mounting face was machined - note the bit of JBW where some of the earlier clamp-juggling failed:



Turned over yet again, but this time with stable and secure clamping surfaces available, I could clean up the inside edges. In an ideal world this would just be a quick filing job but the first error in the original drawings comes into play here. The width of this slot in the bed plate is shown as 1.5", exactly the width of the crank webs that have to turn in the slot (the original GA has the slot drawn with some useful clearance), so I opened this up to 1.625" with a boring head and then the cutter here:



Yet another inversion allows the sides of the main bearing flanges to be brought to size and here I found the only "error" in the casting - one side was displaced ~1/16" towards the centre line and the far side didn't clean up completely. This doesn't look like causing any real problems with the bearing's lateral location, if it does then it's back to the JBW and a bit more machining. Dental mirrors can be very useful things as well:



The last operation (for this post) was to face off the main bearing split line ready to fit the bearing caps. I thought the setting the 30 degree angle by the scale on the Aciera table was sufficiently precise:



If I'd thought this through properly I'd have clamped up the part before tilting the table, otherwise you need four hands to fiddle everything into place. This stays set up until the holes are drilled for the bearing caps.

David



Offline b.lindsey

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Re: Another Westbury Wyvern build
« Reply #18 on: January 18, 2019, 02:27:48 AM »
Hope the beach was enjoyable David. Nice to have you back too though and in the shop again.

Bill

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #19 on: January 18, 2019, 03:08:59 AM »
Thanks Bill, it was. My late father-in-law bought the land around 1955 and he and a couple of mates built the house over the next few years. There's a dirt road across the front then the creek and beach (below at sunset):



David

Offline steamer

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Re: Another Westbury Wyvern build
« Reply #20 on: January 18, 2019, 03:55:53 AM »
Nice Set ups!    Gotta love the Aciera!

Dave
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Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #21 on: January 27, 2019, 11:02:08 AM »
Yes Dave, the F3 is going to star again a bit later!

The main bearing caps come as a single casting and I did as much machining as I could with them still together. After a quick clean-up with a file they were fixed upside down on parallels to mill a clean under surface:



then turned over and the surfaces for the securing nuts milled to thickness:



followed by one end as a reference face (still well outside the finished dimension):



the fore-and-aft centre lines of the lubricator bosses were found by eye and the fixing holes drilled and counter bored on those:



Now the caps were sawn apart, fixed to the baseplate and carefully machined to width. One of the critical bits of alignment in the whole build comes next - getting the crankshaft centre line bang on to the bearing split line and also getting the cylinder mounting hole centre at the same height. Here is another of the Aciera's many clever features, it's easy to turn the vertical head through 90 degrees and use the X-direction power feed for drilling and boring:



After marking out on the surface plate I used a needle and magnifier to pick up the CL of the crankshaft using the Y- and Z-feeds to adjust the position. The sine vice is just there because, for once, its height is an advantage and gives some necessary vertical clearance. Turn the vice through 90 degrees and the cylinder mounting hole can be drilled and bored:





Dave's right:
Gotta love the Aciera!

With everything back to "normal" the tops of the lubricator bosses were milled off flat:



Now I have to comment on the quality of the four alli castings that I've machined from this set so far. All have had a lot of small pores right through them, not enough to affect the strength but irritating all the same. Here is a macro shot of the main bearing stand bore:



While boring the cylinder mounting hole the freshly re-ground carbide tip went blunt (couldn't believe it at first and scratched my head for a while wonder what the heck was going wrong). I think now that some of those pores must have had sand in them - OK it was a cheap boring bare but these deal easily with cast iron...
I don't have much experience (almost none) with castings and I'd like to know how common this is guys?

David

Offline Jasonb

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Re: Another Westbury Wyvern build
« Reply #22 on: January 27, 2019, 12:32:03 PM »
Graham is the one to know but could be oxide rather than sand, if you can dig some out and the grains are much finer than you would expect for sand then it is Oxide. As you know Aluminium Oxide is used as an abrasive.

I recently had some phosphor oxide in some bronze castings that instantly took the edge off an HSS tool and I don't think my bandsaw is cutting as well since cutting the casting in two >:(

Offline RayW

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Re: Another Westbury Wyvern build
« Reply #23 on: January 27, 2019, 03:23:12 PM »
Hi David,

I definitely can't recall having that problem when I built my Wyvern. I think there may have been the odd minor imperfection in the castings, but nothing that caused me any problems. Looks like you may have just been unlucky and got a rogue casting.

Ray

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #24 on: January 31, 2019, 10:46:49 AM »
Thanks Jason, your suggestion of aluminium oxide in the casting makes more sense than simple casting sand. I haven't been able to find anything in the pores but there are a heck of a lot of of them. If another tool goes blunt I'll stop and take a good look.

Hopefully the rest of the castings are more like Ray's batch!

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #25 on: February 17, 2019, 07:34:33 AM »
The next bits of the Wyvern are the crankshaft and main bearings. The bearings are plain turning from bronze bar - no pictures of the set-ups but the bits will appear in later shots. The crank webs were turned from 3" FCMS blank, first brought to thickness and the central hole drilled, bored and reamed. The outside diameters were finished with the webs on an expanding mandrel:



The 2" - 3" micrometer doesn't come out of the box very often but it allowed me to get the two parts very close to the same size.

With the two webs stacked up, located by two V-blocks, and the central hole aligned to the mill axis the pair were offset for the crank throw and the crank pin holes reamed:



Web drawings were printed 1:1 and stuck to the blanks with spray adhesive so the shapes could be roughed out on the bandsaw. Bits of 1/2" PGMS served to align things in the vice and the faces cleaned up:




OK, a ruler dimension might have been good enough for the shaft length but I'm fussy. My slide calipers are only 6" capacity so another way was needed and this made me think (always useful) but for longer than it should have - once you have a DRO then you can measure anything up to the machine travel lengths. Zero the X display with the bit of bar against the top of the angle plate then off you go:



The crank pin is plain turning and the ends of the shaft needed reducing to 3/8" and threading:



Before getting out the Loctite 638 the bits were:



and the finished part looks like:



I'd spent a lot of time filling, rubbing down and painting (rattle can enamel called "Indian Red") and the project now looks like:



I copied tangler's idea and prevented the main bearings from rotating in the housings with 6BA CH screws and you can see that I also made the studs for the base:



I guess the cylinder liner and water jacket are next...

David

Online Johnmcc69

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Re: Another Westbury Wyvern build
« Reply #26 on: February 17, 2019, 10:47:42 AM »
 :ThumbsUp:
Looking good David!
 A great build thread to follow.

 John

Offline b.lindsey

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Re: Another Westbury Wyvern build
« Reply #27 on: February 17, 2019, 02:20:37 PM »
That crankshaft is beautiful David. The whole project is coming along well!!

Bill

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #28 on: February 24, 2019, 12:35:06 AM »
Bill and John, Thanks for the encouragement!

The crankshaft needs two nuts and washers, 17 mm AF hex and 3/8 x 26 thread. I was going to make the thread M10x1.0 but that meant that the core of the crankshaft timing gear would be rather thin so I went back to the Imperial thread. First I needed some hex bar the right size:



The washers and nuts were plain turning and there was enough material for spare nuts so I made four of those:



I'll describe the cylinder liner and water jacket in the next post, right now the water jacket and bed plate are ready for their next coat of paint - "after 1 hour and before 2" are the instructions on the rattle can for re-coating.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #29 on: February 24, 2019, 08:03:52 AM »
Next drawing:



and a link to the .pdf of this: https://1drv.ms/u/s!AnNmmwsT2XIilTYKTFN2ID3Ndlbz

The cylinder liner was from a length of continuously-cast iron, lovely stuff to machine if you don't mind the mess. The outside diameter and one end were finish machined, the OD being made a close sliding fit in the water jacket (next post):



Then, with the material supported by a fixed steady, an extra-long series drill used to start the bore (the extreme length obviously isn't needed, I just don't have anything in between):



followed up with my largest drill (21 mm):



which made lots of swarf in little curls that were interesting shapes:



I thought that these deserved a closer look:



and



Boring the liner to finished size was a nightmare; cast iron steady tips running on the cast surface generated a surprising (to me...) amount of heat and I changed from  ordinary lube oil to a moly-disulphide grease that solved the problem. At first there was no combination of tip, feed and speed that didn't result in horrible chatter. As the bore got bigger I added layers of lead sheet to deaden the boring bar (16 mm diameter) and after four layers this had the necessary effect. The result is ugly but effective:



and gave an acceptable finish which feels better than it looks (original image was 1:1 with a macro lens on a camera with 4032 pixels across):



With the steady removed the parting-off was easy:



The stub of CI  in the chuck was turned and bored to size for piston rings and I got three out of the bit:



I've run a small cylinder hone through and this smoothed off the finish to the feel without apparently changing its appearance but I'm reluctant to do much more for fear of affecting the diameter which is parallel to as well as I can measure it.

Next the water jacket which was actually machined in parallel with the liner but that makes the story way too complicated.

Regards, David

Edit 2019-03-28: Added missing drawing and links DT
« Last Edit: March 28, 2019, 02:35:19 AM by deltatango »

Offline MJM460

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Re: Another Westbury Wyvern build
« Reply #30 on: February 24, 2019, 08:42:40 AM »
More great progress David, enjoying following along.

What did you make of those interesting chips?

MJM460

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Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #31 on: February 24, 2019, 10:24:03 AM »
Hi MJM,
My initial reaction was aesthetic - they made a good B&W picture. I have lots of images of bits of tree bark, moss, paint surfaces etc that I've collected over the years when I saw something that appealed to me.

More technically the chips were in a small range of sizes, many with 2 to 4 turns which suggests that the material is very consistent throughout. Also the big drill still cuts well which is good as I would have to improvise a way to sharpen it (or find someone with gear big enough to do it for me). The chips aren't as brittle as they look, quite springy in fact.

David

Online sco

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Re: Another Westbury Wyvern build
« Reply #32 on: February 24, 2019, 01:10:22 PM »
Nice work David, enjoying following your progress,

Simon.
Ars longa, vita brevis.

Offline Admiral_dk

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Re: Another Westbury Wyvern build
« Reply #33 on: February 24, 2019, 08:58:13 PM »
Looks like a perfect cylinder / ring finish on parts that aren't "broken in yet" to me :ThumbsUp:

Though I must admit that a photo can fool you when taken close up  :thinking:

Offline Art K

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Re: Another Westbury Wyvern build
« Reply #34 on: February 25, 2019, 12:25:46 AM »
David,
Despite the problems with juggling the base and all that came out well. It looks great with paint. How long is the cylinder liner (no not the drill)? The liners I have made were for an air cooled engines and pressed into the cooling fin portion of the cylinder. I bored it first and turned the OD with a disposable glove stuffed inside to kill the chatter. Great work!
Art
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Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #35 on: February 25, 2019, 06:39:46 AM »
Admiral - at least I can't see any chatter! I'll try to remember to take another picture after the engine has run for a while.

Art, Some times I don't see the obvious until it's pointed out - next time I'm making a liner I'll bore it first then turn the outside, possibly on an expanding mandrel which should keep everything stiff enough not to chatter. Stuffing a glove (or a rag?) inside the bore was another good idea. The Wyvern liner is 3.75" long and the bore 1.25".

Thanks David

Offline Ramon

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Re: Another Westbury Wyvern build
« Reply #36 on: February 25, 2019, 08:06:39 AM »
Hello David - apologies for being late to the party ::)

Just been through your thread - looks like you have another nice project here  ;) Some very nice machining on the base and a really lovely job on that crank :ThumbsUp:

Re the cylinder I've always found doing the bore first keeping the od as stock (or as cast) is much the better way to get a good bore first and then bringing the outside to it. Expanding mandrels will hold so securely (and rigidly) with little force required to distort anything - something I'm sure you are aware of anyway :D

Looking forwards to the rest of the build and a nice runner at the end

Regards - Tug



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Offline john mills

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Re: Another Westbury Wyvern build
« Reply #37 on: February 25, 2019, 08:47:21 AM »
when using the fixed steady try a lesses pressure a light delicate feel is required the difference from too much to not enough is not much and slight adjustment can be needed while machining progresses.if you do the bore first
you can use a pipe centre ,alive centre with a cone big enough to fit the bore.while you turn the OD.Ihave done that with 10" long sleeves 4" dia and 1/8 wall thickness.even 1/16 wall.
looks like your progressing well.
  John

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #38 on: February 26, 2019, 09:57:30 AM »
John, Thanks for the tips on using the fixed steady. I almost certainly pressed too hard on the fingers when I was setting them, didn't want to have the work able to move. I've seen fixed steadies with ball races fitted to the fingers which might make setting easier but I'm not too sure about the effectiveness.

Ramon, it's good to hear from you again - have you had more "distractions"?
Thanks for the comments! The finish on the crank is partly down to Garryflex (your advice lead to buying a bunch of Garryflex blocks) and partly to draw filing. You reinforce the previous advice re boring first then turning the outside for machining thin shells like cylinder liners. This to me is one of those things that is "obvious" once someone else has pointed it out. I'll try to add notes to my drawings with bits of advice like this. Kozo Hiraoka was the master of including advice like this with drawings. On this forum I sometimes feel that I'm serving an apprenticeship with masters spread all around the world! The next project is still sitting in a box on a farm near Huntingdon and I have to make some plans for retrieving these bits later this year - Forncett?

David

Offline john mills

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Re: Another Westbury Wyvern build
« Reply #39 on: February 26, 2019, 10:15:22 AM »
I have used fixed steadies with ball races one on a imported lathe has ones with rollers with radius on the rolling surface with only worked like a pipe cutter cut or rolled a lovely groove to get bigger dia in i made bronze tips with i get to work well.I have seen rollers used with worked well too and on big diameters and heavy probably  the best for that work ,such as pulley or rollers 780mm dia 2 meters long or shaft 350mm dia   3 meters long.   

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #40 on: February 26, 2019, 11:09:29 PM »
The cylinder water jacket is a cored casting and this turned out to be close to being square across the ends with the cored hole close to running true in the centre. A bit of work on one end with a file trued it up enough to allow me to mount the casting in the 4-jaw and true the other end:



I bored the cored hole out to diameter without a hint of chatter (I was so focused that I forgot to take a picture) then opened up the water space with a shop made grooving tool. Despite trying different tool heights and two re-grinds this produced probably the worst surface finish I've ever put on a piece of metal but it will serve the purpose:



With a clean bore at each end the piece went on to an expanding mandrel and both ends were given a truing cut and the piece brought to length:



and the bottom flange cleaned up on the surface that will take the nuts:



This probably should have been spot-faced but that needed a tool making and once painted and with nuts and washers in place the appearance will be OK.
Clamped to an angle plate the water inlet and outlet bosses were milled flat and the water holes drilled:



I wanted to get the water jacket and baseplate painted before moving on so the last work on the baseplate was to drill the oiler holes in the bearing caps. The way these work out is that the oil holes hit the bearing bushes on a tangent :



Once the paint dries I can fit some studs and start to assemble something looking like an engine.

David

Offline Chipswitheverything

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Re: Another Westbury Wyvern build
« Reply #41 on: February 27, 2019, 01:10:42 PM »
Somehow had missed this log of the Wyvern, so Just been enjoying looking through the build log from the introduction a couple of months ago: great photos of the machining sequences, fine drawings, and very nice progress on the build itself.   Your Aciera mill is a beauty...       Cheers, Dave

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #42 on: February 27, 2019, 08:40:30 PM »
Thanks Dave! Pleased to have you along for the story.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #43 on: February 27, 2019, 11:20:22 PM »
Here is a family shot of the progress to date:



I took this in the bright sun to give a better idea of the colour. Summer is nearly over - officially - but we have four more days of high 30s and too warm nights to contend with.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #44 on: March 07, 2019, 01:05:40 AM »
I've had more workshop time in the last week and finished the piston and most of the cylinder head so it's time to write up some more of the progress. I have also been working on the drawings as I find errors and omissions and I'll post a new set soon.

The piston started as a rough alli casting and fortunately I had Rod's (tangler) experience, and Jason B's advice, to forewarn me of the problems and provide the solutions. In the picture the boring bar is only there as a pointer while I line up the cored inside of the piston casting to run close to true with the mounting stub in the 4-jaw:



the outside was around 2 mm off centre and starting with that would have led to problems with the piston skirt. With that setting I turned the outside true but still well over finished size:



then reversed and held in the 3-jaw to turn the mounting stub true:



so that the part could go into a collet for the rest of the machining. Starting with truing the inside of the skirt up as far as the gudgeon pin bosses and you can see that this failed to clean up properly to drawing diameter, think I'll have to live with that:




The outside was turned to finished size and the piston ring grooves cut in:



I aligned the as-cast slot between the inside bosses with the y axis of the mill using a bit of metal (no picture) and used a long end mill to clean up the gap:



then turned the part round, aligned it using the same method and drilled and reamed the gudgeon pin hole:



and parted off the piston from the stub:



Back in the 3-jaw chuck with some thick paper for protection the piston was finished to drawing length:



I got a bit nervous here about the thickness of the piston crown but this actually worked out close to the drawn 1/16" perhaps more by good luck than anything when you consider the quality of the casting seen at the start. Like the other alli castings in the set this one has a lot of ugly small pores, I'll find out when the engine runs if these weaken the crown enough for it to fail. For anyone else building Wyvern it would be worth thinking about ignoring the casting and making the piston from bar stock, probably simpler and certainly better looking than this one.

David

Offline Admiral_dk

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Re: Another Westbury Wyvern build
« Reply #45 on: March 07, 2019, 11:20:07 AM »
Nice family shot and the piston looks good too - keep up the fine work  :cheers:

Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #46 on: March 13, 2019, 02:31:09 PM »
Excellent progress  :praise2:  :wine1:

Tjark had a problem with a porous piston crown on his Kiwi that leaked sufficiently to lose compression. Hopefully yours is not so bad.
Best regards

Roger

Offline b.lindsey

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Re: Another Westbury Wyvern build
« Reply #47 on: March 13, 2019, 02:39:26 PM »
Still following along here too David. Had missed a few posts so nice to see the excellent progress being made.

Bill

Offline Tjark

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Re: Another Westbury Wyvern build
« Reply #48 on: March 13, 2019, 06:33:27 PM »
Roger is right, i had problems with a casted piston.
One small inclusion, almost not visible caused a lot off problems.
Have made one out off solid bar and this worked well.
David, by the way the engine is very good looking so far.
Hoop you will have no trouble running the engine.


    Tjark.
« Last Edit: March 13, 2019, 06:38:52 PM by Tjark »

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #49 on: March 14, 2019, 12:03:31 PM »
Thanks everyone! Particularly for the info re Tjark's problem piston. I hadn't considered that a pore, or a series of connected pores, might make a track through the crown. A layer of JB Weld on the inside of the piston crown might prevent leaks and add strength, wouldn't be hard to do either.

David

Offline derekwarner

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Re: Another Westbury Wyvern build
« Reply #50 on: March 15, 2019, 04:50:01 AM »
David....simple open poured casting in aluminium is prone for defect due to porosity [entrapped air bubble during the pour]

This is not so important with structural or mechanical components, yes where a localisation plastic metal repair be effected

Having said this, any defect [in a component subjected to any pressure] established during preliminary machining should best render the casting as defective

Return to manufacturer or machine from Grade quality referenced bar stock which has far higher mechanical strength and machinability

Would be terrible to progress a piston with a defect.......add plastic metal to the piston internals underneath the  crown.......only to have a steam bypass  :zap: some time after completion of the engine

Derek
« Last Edit: March 15, 2019, 04:53:22 AM by derekwarner_decoy »
Derek Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #51 on: March 17, 2019, 01:09:54 AM »
Thanks Derek, I've put away the JBW! Without any guarantee that a new casting would be any better, machining from the solid will be the way to go.

Next drawing:



and the .pdf is at: https://1drv.ms/b/s!AnNmmwsT2XIilTND5H63TKsxS3t6

The next part is the cylinder head which is a complex shape with a lot of surfaces to machine. The casting had a rough finish with small bits of the fins missing so the first job was filling (JBW) and filing to removed the worst of the surface defects. Then I gripped the chucking stub in a my biggest tailstock drill chuck and presented it to the 4-jaw for clamping:



and cleaned up the chucking stub:



so that the casting could be held in a collet to level the underside and machine out the combustion chamber as well as forming the important recess that clamps and seals to the top of the cylinder liner to dimension:



With the underside machined this was pressed down onto parallels and the stud holes drilled and counterbored:



I then made the studs and checked the fit of those and that the recess was just shallow enough to seal:



The paint on the water jacket turned out to be slightly soft (too thick a coat, probably) and picked up bits of swarf, a rub down and re-spray will fix that. The chucking stub was used again to mount the part in the dividing head to machine the three side faces and drill the holes for the valve cages and the inlet and exhaust passages. The fourth side is just a small flat to take the camshaft bearing:



The bottoms of the ports to take the valve cages have to be bored flat and for this I backed up the grip from the collet with an angle plate:



Setting up this way makes drilling the inlet and exhaust tracts to the correct depth easy:



The last surfaces in the combustion chamber were formed with a 5/16" round nose slot drill:



The chucking stub was cut off and the head clamped down to machine and drill the rocker arm mountings and drill and tap for the spark plug:



I had to juggle a compromise between the correct coordinates for the rocker arm pivots and the centres of the bosses on the casting, there may be some adjustments needed to the arms when these are made. The head now just needs a few studs making and a coat of paint (matt black stove paint I think) and it will be ready to assemble.

David

Edit 2019-03-28: Added .jpg and link to .pdf of next drawing - DT
« Last Edit: March 28, 2019, 02:40:44 AM by deltatango »

Offline scc

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Re: Another Westbury Wyvern build
« Reply #52 on: March 17, 2019, 09:33:33 AM »
Very nicely done :ThumbsUp:                            Terry

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #53 on: March 17, 2019, 11:29:35 AM »
Thanks Terry!

Looking at the last picture in the previous post I can see that I forgot to say that I've changed the design to use a bronze insert for the exhaust valve and not to seat the valve in the head as drawn by ETW. For this I tapped the head M12 x 1.0 and cut a 5/8" hex on the body of the insert. The inlet valve housing could easily have been made the same but I'd already bought the casting so I machined that. Pictures next time.

David

Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #54 on: March 17, 2019, 05:25:21 PM »
That cylinder head looks quite a tricky thing to hold and machine  ::) You seem to have got it sorted  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Offline Muddy Rutter

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Re: Another Westbury Wyvern build
« Reply #55 on: March 18, 2019, 01:54:42 PM »
It's good to see your progress David.

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #56 on: March 26, 2019, 11:02:28 AM »
Having a nearly finished cylinder head it's time to make some of the bits to attached to it, this time the valves and housings. Like other people I've modified the design to have both valves in inserted seatings rather than have the exhaust seating directly in the alli of the head (probably left over from having the head cast in iron). These could both be the same from bronze bar stock but as I'd already paid for the inlet side casting I might as well machine this as a start. There was a lot of extra metal on the raw casting so no worries regarding finding the finished part inside it. Mounted in the 4-jaw I turned the valve seat end to fit the hole in the head:



which could then be held in a collet to rough down the other end:



and drill and bore this to take the valve spring:



The flange was filed to shape using a steel guide made from the drawing. The exhaust housing was very much the same apart from the M12x1.0 thread and a 5/8" hex milled on to give a spanner something to get hold of:



After the 45 degree seatings were machined (see later), the final operation on both parts was to put a 2 degree taper on the outer end to improve the appearance:



The two valves were turned back-to-back from stainless steel (grade unknown but it may not have been free-cutting!). SS is a poor conductor of heat and flood coolant was necessary for running down the stem to 1/8", first with a Crobalt bit in the Diamond Tool Holder, then finishing with a sharp carbide bit:




Getting the lathe set up to turn the valve seating faces was tricky as its necessary to machine the valve faces and the bronze seatings at the same setting. The top-slide was set over to 45 degrees and the lathe run in reverse to machine the valves:



I was concentrating hard to avoid mistakes on the bronze bits and forgot to take a picture - sorry! Before separating the two valves looked like:



The springs were supplied in the kit of bits from Hemingway, I made two spring collars and 5BA nuts from MS and at this stage the finished set of bits looked like:



The final nerve-racking op was to fit the bronze seatings into the head and drill through for the inlet and exhaust tracts. All went well and the bits all fit together:



and into the head:



Currently the family looks like:



David

Offline MJM460

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Re: Another Westbury Wyvern build
« Reply #57 on: March 26, 2019, 11:13:20 AM »
Great progress David.  The family is really coming together.

MJM460

The more I learn, the more I find that I still have to learn!

Offline Muddy Rutter

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Re: Another Westbury Wyvern build
« Reply #58 on: March 26, 2019, 11:55:46 AM »
Looking good David and really useful to follow.

Nick

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #59 on: March 28, 2019, 02:54:18 AM »
Hi everyone,
I've created a new version of the Wyvern CAD model and drawings. These incorporate the errors, omissions and modifications that have been needed as the build has gone on. The exhaust valve bronze housing now has a 5/8" hex for tightening rather than tommy bar holes and the timing gears are close to correct sizes. The flywheels hubs have been modified (again) to clear the crankshaft timing gear. A bunch of useful or omitted dimensions have been added.

I've edited the previous posts where there were pictures or links and added missing drawings to two other posts. Hope all these work OK.

When the timing gears, camshaft and valve gear and the con-rod are done then it will be on to the last sheet of drawings (ignition and carby).

At the end of next week we are going to Japan for two weeks so progress will stop until the end of April.

David

Offline Muddy Rutter

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Re: Another Westbury Wyvern build
« Reply #60 on: March 28, 2019, 06:45:43 AM »
Thank you David for the updated drawings - they are really useful. Hoping to get some pictures up soon of my progress to date and meanwhile I hope you enjoy your trip to Japan, assuming it’s a holiday of course. Nick.

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #61 on: March 28, 2019, 10:13:10 AM »
Hi Nick, I and probably the rest of the forum are looking forward to seeing some more Wyvern pictures.

Japan is holiday. While I was working I went there regularly from 2000 to 2015 but didn't have much time for tourism, this time I get to travel for myself. Sue is going for the first time and is apprehensive of the very big differences (e.g. being effectively illiterate). I hope to convince her that it's a great place to visit and not really all that difficult a place to be.

David

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #62 on: May 19, 2019, 08:24:58 AM »
OK, after two weeks holiday and a three-week "welcome home" dose of 'flu its back to work on the Wyvern. I did do a bit of shopping in Tokyo, places like this tool stall in Akihabara are hard to resist:



The other places worth a visit are a chain of stores called "Tokyu Hands", high quality small tools (a very fine file; replacement tips for soft-jaw pliers; packets of carborundum powder; really sharp, but reasonably cheap, taps and dies all came home with me).

Ah, yes, Wyvern - the next bits are the conrod and bearings. The rod could be carved from the solid but I chose to have a go at fabricating it. The shaft was found inside a part of the hoard:



The shallow taper was turned by offsetting the tailstock - the first time I've tried doing this - and this worked well. The little end and flange for the big end were from odds-and-ends. The brain fog induced by the 'flu had two effects firstly I forgot to take pictures and, more importantly I failed to think about how I was going to hold the finished taper shank for the rest of the machining. Starting again was probably the easy way but instead I tried 3D printing a fixture in ABS and the final version looked like:



Each half of the hole up the middle is tapered to match the measured shaft. The first attempt left a gap between the two halves into which the jaws of the four-jaw SCC slipped (that brain fog again) so when I came to use the fixture I had to pack it with metal strips. Here the big end flange is being cleaned up after silver soldering:



and the other end being scalloped before attaching the little end:



The oil hole drilled (should have left this until the bronze bush had been fitted):



then it was time to dig out the GM casting for the big end:



this was milled to length then thickness:



hacksawed in two (there was a lot of spare metal so this wasn't stressful) and milled to thickness:



The halves were fixed together with superglue and the crankpin hole drilled and reamed. If you look too closely at this picture you can see that I didn't even up the milling and the sides won't clean up to circular - still learning about dealing with castings:



More superglue (with screws for safety) stuck the part to a 1/2" mandrel and the sides cleaned up to width:



The new version of the ABS fixture held the shaft to drill and ream the little end for the bush:



and the flange milled to width:



The final use for the fixture was drilling the stud holes in the flange:



Two made-to-measure 4BA studs, plus a bit of polishing, finished off the job:



The 3D printed fixture did what was asked of it but I wouldn't use the method for any task requiring precision. An improvement would be to use a harder material than ABS (e.g. polycarbonate) as I could feel distortion when clamping up. The superglue worked well as an alternative to soft solder for holding the bearing halves together but I did make a point of leaving it overnight to cure fully.

David




Offline Roger B

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Re: Another Westbury Wyvern build
« Reply #63 on: May 19, 2019, 09:30:36 AM »
That's an interesting take on making a conrod   :ThumbsUp:  :ThumbsUp: Nicely done  :praise2:
Best regards

Roger

Online Ye-Ole Steam Dude

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Re: Another Westbury Wyvern build
« Reply #64 on: May 19, 2019, 09:41:43 AM »
Hello David,

Coming along nicely :ThumbsUp:

Have a great day,
Thomas

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #65 on: May 19, 2019, 10:03:15 AM »
Thanks, Roger and Thomas - what time is it in Texas??

David

Online Ye-Ole Steam Dude

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Re: Another Westbury Wyvern build
« Reply #66 on: May 19, 2019, 11:20:15 AM »
Thanks, Roger and Thomas - what time is it in Texas??

David

Hey again David,

I am on Central Daylight Time for the US and it is now 5:19 am Sunday morning.

Have a great day,
Thomas

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #67 on: May 19, 2019, 12:00:33 PM »
Hi Thomas, I thought you must have been up early! Thanks again for looking in on Wyvern.
David

Offline gbritnell

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Re: Another Westbury Wyvern build
« Reply #68 on: May 19, 2019, 12:06:56 PM »
Hi David,
Very nice fabrication log on the connecting rod.
gbritnell
Talent unshared is talent wasted.

Offline deltatango

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Re: Another Westbury Wyvern build
« Reply #69 on: May 19, 2019, 12:38:15 PM »
Thanks George,
If this version breaks and I have to make another one then the big end flange will have a collar on the shaft side to increase the surface for the solder. It would look better as well! It should also be possible to build up a part like this using adhesives, maybe I'll give that a try when the engine is running and I feel like tidying it up.

Cheers, David