A New 5cc Aero Diesel Engine Project

[Don1966]

Ramon you just keep coming up with new stuff for me to build. Love you fixture it's so useful for both lathe and mill. Still following along here with great interest.

Don

[Ramon Wilson]

Ah! "Sorry about that" Don  - I must admit it is a versatile and very useful but easily made fixture, it certainly gets plenty of use on these small engines.

A small anecdote - "Sorry about that" is in quotation as we had a draughtsman/designer who was renowned for mistakes which would swiftly be dismissed with a pencil stroke or two and the utterance of those three words. The guys in the toolroom chipped in and we had a proper rubber stamp made with the legend 'A Genuine RJJ Sorry About That' with which all relevant drawings were gleefully stamped 

Following on from the last post the 'secondary' inner shafts were turned from the shanks of 8mm high tensile cap head bolts and with a smear of high strength Loctite pressed in using the small home made flypress.

Set back in the lathe in soft jaws the shafts were roughed down to plus .5mm on diameter and faces on the front ends.


This may be of interest to some one ..... I don't use the leadscrew for such turning - just the saddle handwheel but it was always felt that the standard Myford version is a bit small as far as leverage is concerned so a while back I made a new saddle handwheel which has improved matters considerably on this kind of op as well as general turning - certainly wouldn't go back to the old one now. 


After the secondary roughing they were ready for finishing between centres


This little driver plate has seen considerable use now. The centre is removeable as it is trued each time it's used to ensure concentricity - it's just about ready for that next time.


The shaft can now be finish turned using the crankpin as a driver - the red line denotes the limit of thread. These were turned to 0.03-04mm up on diameter and then polished down to size with fine emery and oil


The shafts could be screw cut at the same set up but were done as a secondary op to the finishing - no gear box 


With the front ends finished that fixture was pressed into service on the faceplate for turning the crankpins to finished size - the reduced portion is the drive for the rotor disc. Don't take any stock by the tool - I confess that when it comes to grinding lathe tools I'm the laziest around - it's very much if it will cut efficiently it'll do. I guess after all it's only the very point that does the work 


The shafts after finish turning ready for that last op - shaping the web and one which is always a bit fraught after all the work gone before.

I usually use a vise and a vee grooved parallel to hold the shaft but this time decided to use a block made at work for grinding work - like a big  finger plate only 50mm thick. I don't know why I haven't thought to use it before as it was perfect for the task  Unfortunately  the pics taken are really blurred but I'll take some more tomorrow.

All went well though so that's another part done .....


All the parts made so far are individually bagged in small polybags to offer some form of protection. The box they're in grows fuller but there's still a way to go yet. The plan is to keep on with all the steel parts now so it's the liners next and some of the smaller ancillary bits.

That's it for now -

Regards  - Ramon

[ths]

That's very instructive, Ramon. Are you roughing out with carbide and finishing with HSS? The end result looks superb, well,from this far away at least.

Hugh.

[Don1966]

Ramon, I have a question in regards to your soft jaws. Is the chuck a Myford original or one with soft jaws that came with it? I have been looking for soft jaws for my existing chuck, but can not seem to find them. A chuck with soft jaws cost quiet a bit.
Your cranks came out great. Do you always use bolt material for the threaded portion of the shaft?

Don

[b.lindsey]

I like that fixturing Ramon, clever idea using the crank pin as the driving ""dog." The crankshafts certainly did come out well but I didn't expect otherwise

Bill

[Ramon Wilson]

Hi Bill, Don, Hugh, et al, good to hear from you as usual.

Don, That three jaw - a Pratt-Burnard precision ground scroll would you believe, goes way back to my first ML7 (possibly even the ML10 before that - does that have the same chuck mounting as the 7 ? Now that is a long time ago  ) It's done sterling service but has seen better days now. It was very pricey in it's day but when I tried to replace it a year or three back the cost was simply astronomical  and totally unjustifiable.

The soft jaws were bought from an agent who used to regrind all our cutters - they've been in use a long time and I am very frugal with machining them - the tapped holes are for holding slices of hexagon bar which further extend their use - I do have a spare set but was thinking the other day that these ones could be resurrected at some stage by silver soldering pads to the front as they are only mild steel after all - any one else done that?

Re the use of high tensile bolts Don, so far all the engines I've made have had the shafts made this way. Initially done to conserve a small, and only, piece of En24t it proved a viable way to limit the amount of this material both from an availablity and excess machining point of view. With that front end reducing from 32.0 diameter to 6.35 quite a bit of material and energy is saved. Bear in mind these engines will only ever get bench run though they are given their head when the situation allows. So far nothings gone awry - yet 


Hugh, I'm not keen on using carbide at home. Well versed to using it at work I feel the power of the Super 7 isn't really up to the demands of using the carbide efficiently so virtually all turning is done using HSS. I was given this tool by a good friend quite recently and decided to see if it would speed up matters on this En24t which it has - a big improvement over HSS but I still don't see a need to use it generally other than tough material or the odd hard spot in a casting.

Re that block referred to last night - heres some pics of the set up to mill those webs...

The block was made at work from some extremely tough cast iron - a redundant twenty ton press bedplate.Wheeled into the machine shop by the press shop foreman one morning with a 'Is this any good to you otherwise it's going in the bin remark' it was swiftly reduced to sizable chunks and stored for that rainy day  . Have no idea of the grade but very tough. I made the Waller cylinder from a piece of it and also a dividing device for the mill before redundancy took over - I guess like so much else it all ended in the scrap bin

It has three vee grooves ground in and plenty of tapped holes for clamping screws.


It was much easier to align the centrel line of the pin to that of the shaft than when held in the vise....


....and then mill either side to stops.


I don't think I've used it since leaving work - that could now change

Made a start on the liners today.  Once again these are made from freecutting En1a which is a good combination with a cast iron piston. Bored the blanks to size first using the expanding mandrel made for the previous ones as a plug gauge then roughed the outer surfaces in the chuck before finishing the outer surfaces to the bore on the same mandrel.

Finished ready for milling the transfer and exhaust ports


Where's the fourth one? Well that is a spare left over from the prevous engines and just needs the ports finishing by filing - more on those ops later.

The weather at last has turned so that can mean only one thing - distraction - the garden beckons 

Regards for now - Ramon

[peatoluser]

Ramon, it's always a pleasure to log onto your posts . There's always something to learn and admire.
following with great interest

peter

[Bogstandard]

Ramon,

I do have a spare set but was thinking the other day that these ones could be resurrected at some stage by silver soldering pads to the front as they are only mild steel after all - any one else done that?

Since buying my far eastern lathe about 5 years ago, I have stuck with far eastern chucks, both 3 and 4 jaw self centering, as 50% of my turning work is done using soft jaws, most of the other work is done in a collet chuck. They are very cheap to buy for these far eastern chucks, normally around 25 UK pounds per set.
So if I am doing any normal turning with the scroll chucks using the normally supplied hard jaws, parting, facing etc, they are plenty good enough anyway.

So for the person who doesn't have a lot of cash to spare to buy very good quality chucks, far eastern chucks are a good compromise if you do a lot of soft jaw work, as there is no difference after they are bored to size from a very expensive one.

I think I have bought almost all of mine from RDG, here in the UK.

Very good write ups and descriptions BTW.


John

[steamer]

Hi Bill, Don, Hugh, et al, good to hear from you as usual.

Don, That three jaw - a Pratt-Burnard precision ground scroll would you believe, goes way back to my first ML7 (possibly even the ML10 before that - does that have the same chuck mounting as the 7 ? Now that is a long time ago  ) It's done sterling service but has seen better days now. It was very pricey in it's day but when I tried to replace it a year or three back the cost was simply astronomical  and totally unjustifiable.

The soft jaws were bought from an agent who used to regrind all our cutters - they've been in use a long time and I am very frugal with machining them - the tapped holes are for holding slices of hexagon bar which further extend their use - I do have a spare set but was thinking the other day that these ones could be resurrected at some stage by silver soldering pads to the front as they are only mild steel after all - any one else done that?

Re the use of high tensile bolts Don, so far all the engines I've made have had the shafts made this way. Initially done to conserve a small, and only, piece of En24t it proved a viable way to limit the amount of this material both from an availablity and excess machining point of view. With that front end reducing from 32.0 diameter to 6.35 quite a bit of material and energy is saved. Bear in mind these engines will only ever get bench run though they are given their head when the situation allows. So far nothings gone awry - yet 


Hugh, I'm not keen on using carbide at home. Well versed to using it at work I feel the power of the Super 7 isn't really up to the demands of using the carbide efficiently so virtually all turning is done using HSS. I was given this tool by a good friend quite recently and decided to see if it would speed up matters on this En24t which it has - a big improvement over HSS but I still don't see a need to use it generally other than tough material or the odd hard spot in a casting.

Re that block referred to last night - heres some pics of the set up to mill those webs...

The block was made at work from some extremely tough cast iron - a redundant twenty ton press bedplate.Wheeled into the machine shop by the press shop foreman one morning with a 'Is this any good to you otherwise it's going in the bin remark' it was swiftly reduced to sizable chunks and stored for that rainy day  . Have no idea of the grade but very tough. I made the Waller cylinder from a piece of it and also a dividing device for the mill before redundancy took over - I guess like so much else it all ended in the scrap bin

It has three vee grooves ground in and plenty of tapped holes for clamping screws.


It was much easier to align the centrel line of the pin to that of the shaft than when held in the vise....


....and then mill either side to stops.


I don't think I've used it since leaving work - that could now change

Made a start on the liners today.  Once again these are made from freecutting En1a which is a good combination with a cast iron piston. Bored the blanks to size first using the expanding mandrel made for the previous ones as a plug gauge then roughed the outer surfaces in the chuck before finishing the outer surfaces to the bore on the same mandrel.

Finished ready for milling the transfer and exhaust ports


Where's the fourth one? Well that is a spare left over from the prevous engines and just needs the ports finishing by filing - more on those ops later.

The weather at last has turned so that can mean only one thing - distraction - the garden beckons 

Regards for now - Ramon

Nice Fixture Ramon!.....I like it!

Thats about 100 x 50 x 25 or so?

Dave

[Ramon Wilson]

Hi John, Thanks for your input.

Yes I have a far eastern 5" 3jaw still awaiting the back plate to be fitted though I do not have any soft jaws for it as yet . As you say, cheap or expensive, the beauty of soft jaws render either attribute more or less equal 

The PB chuck has the internal Myford fitting and that was what I was more interested in in replacing. Having decided a new one was out of the question I was fortunate enough to find a little used replacement at the last but one Myford Open Day. This is a Toolmex version with a heavy reversed backplate and internal thread. Using it yesterday to bore those liners it literally seized solid, the jaws stuck half way. I stripped it down to find it absolutely full of swarf and thick grease. Examination showed that the back plate inner face doesn't meet the chuck inner face so allowing swarf to get in. An o ring popped in between will hopefully put an end to that.

Dave (Steamer), a little bigger - it's 125 x 75 x 50

Regards - Ramon

Peter - My apologies, I didn't mean to ignore you. Thanks for your kind comments - it's good to see you have an interest but yours ,for me, is much more inspiring

[Ramon Wilson]

Hi Guys had a repreive today - it rained like hell  only one place to be then 

Just a few pics of cutting the porting in these liners which may be of interest to someone. Not a difficult operation but one that has to be done with a degree of accuracy if the timing is to remain as designed. The original liners were quite 'high tec' in their day - for model aircraft engines that is  - in that they were investment cast steel and had the transfer ports cast in. Close examination of the Mk1 & 2 originals showed the tops of the transfer ports to be flat and square to the bore whereas most other engines of the day having angled ports being drilled or milled giving an elipse form inside the liner.  I filed the Mk 1 & 2 ports to a gauge but it occurred doing these that providing the holes were correctly located filing could be done until the inked up port just showed an indication of ink. The ports were made a bit larger as per the liner in the Elite that I was loaned. You will notice some slight difference in them - that is by choice, just to see if theres any performance difference.

First off was to mill the passages...


...then set the milling attachment at 35degrees and plunge cut the ports with a 3mm FC3 cutter. The position of this was established by CAD and datumed off the lower surface of the exhaust flange which is the datum face for the timing for both ports. The liner was moved radially to widen the cut to match the passages by engaging backgear and applying radial motion by turning the main drive pulley by hand - there's a surprising amount of control doing it like that 


The cut outs were done at the same time as these would be used to align the liner to the rotary table for the next op....


....which was to cut the exhaust ports using the same cutter as was made for the Mks1 & 2


All finished ready for lapping. The one with the fins on is for the Elite Mk2 which had shrunk on fins and a separate head. I popped the liner in the freezer whilst I had my dinner and then later heated the fins with a hot air gun. Despite having a rod through the bolt hole as a guide to align the bolt hole with the pillar between the exhausts the speed at which it contracted did not give enough time to get perfect alignment  It ain't coming off now though


It will be a while before the lapping gets done - I'll leave the cast iron till last. Next will be some of the less exciting ancillary bits - cylinder bolts and rotor pins etc - in the meantime the box of goodies grows 


Time for a day off, weather looks favourable tomorrow - it's my first race 

Have a good weekend now
Regards to all - Ramon

[Jasonb]

Hope the wind blows for you, assuming its a sailing race.

J

PS Good to see your article in MEB.

[steamer]

Hope the wind blows for you, assuming its a sailing race.

J

PS Good to see your article in MEB.

Ditto!    Nice article and hope you do have fair winds!

[Meldonmech]

Hi Ramon,
                 What a Brilliant article, the finish you have on the engine body is better than die castings.
The machining tips, tooling, and set ups are excellent. I used the holding fixture for taper ball handle making way back when building the Quorn T&C Grinder, and I agree it was very useful , pleased you  passed that one on. I have made made quite a few special milling cutters using the same materials and hardening techniques as yours, however it never occurred to me to make the cutter heads separately. It  saves on materials,  can be easier to make, and the shank can be used for various heads.
           I started reading this article today and couldn't put it down like a good thriller.

                                                        Well  Done          Cheers  David

[Ramon Wilson]

Hi Guy's - where on earth has that week gone ? Time certainly flies when you're enjoying yourself that's for sure.

Firstly thanks for your kind words David - it's always nice to hear that someone benefits.

Despite some garden distraction what time managed in the workshop has been well spent though. All the cylinder head bolts are turned and slotted, the stainless pan head screwshave been reshaped to round heads and  the rotor disc wear plates and rotor pivot pins made.

The wear discs were apparently an aftermarket part no doubt to reclaim a worn backplate face. The original Mk1 I had loan of did not have one fitted and the circular wear marks were quite prominent in the ali surface. The 5cc Mk 1 was left as per the original but the Mk 2 had a plate made which is also what has been done here on all four.

The original appeared to be a stamping but these have been made by parting off some En1a of the correct diameter about 1mm thick then holding it in soft jaws and facing it to 0.8mm. The blanks were then lapped to a fine finish on the wearside using a pot magnet as a holder. Lapped on a lapping block to begin with they were finished by polishing on 2500 grit Wet and Dry on a ground cast iron surface.
Still holding it in the soft jaws the inlet segment could be removed - I thought of Vince and his flywheel doing this - same op, just a lot smaller but no doubt same anxieties 

The edges were defined first - any error here alters the desired timing.


Then the segment removed


They fit into the recess in the backplate and are held by the rotor pivot pin. No means are there other than clamping pressure of the pin to prevent them rotating - obviously if they did it would alter the timing but that isn't something that's occurred so far


I can't remember who but someone was recently asking about rounding something in the lathe - these stainless screws were soon reshaped using a home made cutter - the profile was just milled into a piece of GFS and heat treated. Note the colour - because of the amount of screws to do and their toughness this was tempered to light straw.

Shape to begin with...


....and finished.

The tool shows no sign of wear after shaping 48 screws - that includes 16 on the previous engines. Hope that's of use to someone.

The rotor pins were turned from silver steel and screw cut UNF 8-32 L/H. (Only suitable L/H tap available). I've screwcut some pretty varied materials over the years but nothing can be worse than silver steel. for some reason this material is always a pig to screwcut and this time would prove no different. That said only one had to be made twice and the rest though not brillliant were acceptable.

These were heat treated one at a time so as to give good 'positional' control when quenching. By plunging them into the oil squarely to the surface any potential distortion is kept to a mimimum - particularly at the narrow point where the thread runs out.
A piece of copper tube was tapped to hold the threaded end and the main body of the pin then heated to a bright red. Once up to that it was removed from the flame for a few seconds and allowed to cool to a dull red before quenching in oil. Doing this helps stabilise the temp through the part.

These couple of shots are posed after using the scrapper but give some idea of the colours involved. Because of having to handle the camera this first image has the part somewhat brighter than would be the normal colour taken to.
- this is actually much too hot.....


.....this is more the 'red' ready for quenching


Once quenched the pins were polished back to bright steel and cleaned of all traces of oil before tempering in a tray of hot sand.
The sand should be very hot before putting the part in as this helps ensure consistency if multiple parts are being treated. It is not a good idea to put more than one part in at a time as once up to temp required it's surprising how quickly it will travel through it's desired colour and once past - well 


Finished ready to fit to have the rotors fitted. Though they look near black in the image they are in fact a nice blue going on brown to look at in shop light - well pleased with the outcome


Think I should just say that the above re heat treat is based purely on practical work experience and not one of academic knowledge - this is not to teach granny - just my way of going about heat treat at home based on many hours of doing it correctly with the proper kit in a commercial environment.

Well that's as far as things are at the moment - the rotors are next so the workshop will be permeated with that nice aroma of machined tufnol and after that its on to the pistons and finally some fitting work 

As always hope this of use to some one

Regards - Ramon