Super Tigre G32 1cc diesel - a 5cc version

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Ramon

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Hi guys, pleased to tell - it's been a good day ;) for that old cliche that you can learn something most days is not to be dismissed lightly and today was certainly a good one for it to ring true.

Began by making those contra pistons. These can be tricky little things to make not just in getting the right fit but in holding them to do so. Several methods of holding them, most fairly inadequate, have been tried in the past but when I did the 'Racers' though it might have been the Etas I think it dawned that maybe using an expanding mandrel 'in reverse' - removing the screw and allowing it's natural spring to grip the cavity in the top of the CP - might work. On trying it quickly became apparent that as long as there was a good .05mm interference with a slight tapered lead in the grip was sufficient to turn the outer faces and subsequently hone it to fit. It occurred today that if one mandrel was kept purposefully for this and all rear recceses were initally turned to fit they could be opened out later if desired.

This old mandrel was pressed into service, I think it's what I used previously - 12.7mm OD. The CP was bored 12.65 and was then turned and the concave face cut without any slipping problems
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It was felt that the new honing tool was much too wide to be able to use effeciently so I reverted to the old method of using two flat fine india stones - using lots of paraffin and oil as a lubricant this actually works extremely well but control of size is difficult as it's entirely down to feel, judgement of time and constant stopping to clean and check. The first one went fine, three 'goes' and checks and the CP fitted just right - a nice push fit using the drill as a press.
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The second however pushed easilly straight through the bore :eek:
This is not neccessarilly the 'make it again' set back it might at first seem as it is possible to 'grow' cast iron with the application of some heat. Forgive me for refering to him again but good old George in one of his many articles in a US magazine - Model Airplane News I think - described heating a worn cast piston to red heat and - I always thought it said - allowing it to cool. This does indeed work, the average 2.5cc piston growing perhaps 0.02- 0.03mm sufficient for re lapping. Several old diesels and one or two glows have certainly been given a new life using this method over the years. So the CP was duly heated and before I realised what I was doing had picked it up with the tongs and dropped it in the oil instead of letting it cool. Surprise of the day was finding upon measuring that it had grown a whole .06mm - 18.30 initially to 18.36mm. Up the loft and a rummage through the old control line folders and there it was - heat to cherry red and quench in oil :eek: - after all this time in letting it cool ::) 06 is a big difference to .02/3 and a much bigger help if the need is there

The CP, now hard took much more stoning but this time the fit was there and finally there was a set of parts .....
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..well two actually but one set now looks like this ;D
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Having previously got the drum valve to nice running fit quite some time was spent getting the drum valve to run freely as it had distorted slightly in the heat treatment. Having given the case a thorough clean in cellulose the shaft showed constant signs of abrasion. Stoning the distortion gradually improved the fit but it still seemed gritty. Then the penny dropped. The bead blasted surface was still retaining grit - just enough to come off on the hands and find its way to effect the fit of the drum valve. A quick blitz in the Ultra Sonic sorted this out and the shaft fitted without further problems. The rest of the engine went together okay, the only slight bit of fettling was on the outer diameter of the conrod which was just touching the inner surface but, it has to be acknowledged, the compression seal did not seem great, certainly not what was hoped for :(
Finally though, apart from the needle valve it was together at 6pm when with fuel can in my hand ready to try it Sue put her head round the door - "I'm just about to dish up" - ahh perfect timing ::)

So a little later it was strapped in the stand still minus needle valve and some fuel squirted through the ports, the compression screw had to be screwed in a surprising amount when suddenly it fired on the prime :D needle valve immediately fitted and it was off on it's first run ;D ;D
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The revs were kept well down but it has a gorgeous, deep, throaty, 'diesel pop' to it. It is assembled without gaskets but I think that there should be at least a paper one between liner and crankcase. It vibrates a little, that may be down to the low rpm or the mass of material in piston and crankshaft - scaling effect I'm afraid but it's early days that might diminish on a change of prop.

I shall now get the anodising done before assembling the second one so I guess for a 'Work in Progress' that's the end of the line. I confess I'm a mite tired :)

I'll come back with some more pics when they're finished completely.

Thanks for your comments along the way - all of them much appreciated

Regards for now - Ramon


 

rklopp

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Nice writeup, Ramon. I have never tried lapping the piston using the bore or vice versa. What I've typically done is finish the piston together with the contra as a solid rod with some extra length. The extra length helps with measuring and removing any taper. I polish the diameter in with 600- and 1200-grit paper backed up by an old flexible scale. I trim off the extra length, which gets rid of any barreling, and then part off and finish the piston insides, holding it in a soft collet.

Next, I lap the cylinder to fit the piston using the method you described, although I use diamond paste in oil. I have used both homemade aluminum and commercial brass split laps. The latter are so cheap it is hardly worth messing with making a lap. I use a cheapie Asian ultrasonic cleaner with detergent to clean the cylinder before testing the piston fit.

For the nano cylinders, I lapped using 3 micron diamond until I had practically a mirror finish. I don't see much use in trying for "plateau honing" on a 5.5-mm bore. I figure it's best to scale the scratches with the scale of the engine. For the bigger Mill 1.3 engines, I left some of the scratches from the coarser grit lap after lapping some with the 3-micron paste. The hope was to achieve a plateau honed finish. It seems to have worked, because the Mills engines run beautifully and seem to be retaining compression well.
 

Don1966

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Ramon thanks a bunch for the lapping lesson and how to make laps. I really enjoyed it and learn a lot more then I knew about lapping. Will you be showing us how you anodize the engine? That is one thing I would like to learn how to do also.

Don
 

metalmad

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you make it look so easy Ramon :bow:
looking forward to the video.
Pete
 

ShedBoy

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:bow: :bow: :bow: Wonderful stuff Ramon

Brock
 

kutzdibutz

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Absolutely amazing work that is! :bow:

And th_wwp - ah, no, it should read 'We want Vi-de-o!'

Cheers, Karsten
 

Runner

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Ramon, fantastic workmanship, fantastic pictures and write-ups and all done at a pace that beggars belief, no wonder your a mite tired.

Dare I ask since the spinner wasn't fitted, were you able to start the diesel with a flip of the finger on the prop?

Congratulations on a job very well done :bow: :bow:

Brian
 

steamer

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Oh Ramon....what will I do with you....That's not a proper test stand!

It needs more instrumentation! Tell ya what, just because I'm a buddy, send that beaut over here to me and I'll do a proper battery of tests and submit a report....should only take 3 or 4 years to complete....

....... ;D


That's awesome Ramon, and I want to thank you for your excellent write ups! Lapping is another one of those very simple yet extremely powerful tools, and your write up is the best I've seen!

:bow: :bow: :bow:

Dave


 

Ramon

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Hi guys, thanks for the response, nice to hear from you.

Thanks for the insight into your methods 'RK'. I particularly like the sound of doing the piston and contra piston in one hanging though does this not mean you have to leave the top of the liner tighter to get the interference fit required for the CP. Having said that if it's cast then it could be 'grown'. You've also made me think about the kind of 'finish' inside the bore using the technique I described. Though very smooth and as round as I can measure it's not honed. I think on my next engine I will lap the liner first as described then hone it with a cylinder hone to get some decent 'scratches' in the surface before lapping the piston in. BTW have you had any luck with getting those Nano's running yet?

Don, I did the anodising today which went well. I hope you won't mind but I don't really want to go into the process at this stage. I have an article which is due to be published fairly soon in ME describing my attempts so don't feel it would be fair to pre-empt it. Hope you understand. However I did post on here in reply to somones questions on it sometime ago - just the basics but enough to get the idea. Perhaps a search will bring it up

It's not a difficult process and it's certainly worth pursuing.....
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Just remember to wear gloves when dyeing :)
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Well I think that really is it on this thread. Dave, Brian and all the others - I appreciate you taking the time to send thanks and respond. As the Waller engine thread and now this developed so the need to remember to take photos at all stages became a requirement more than just a personal record of some of the ops. You've seen just over 200 on this - there were well over 600 taken and the time to sit and go through them as well as post takes a fair bit of time - usually at the end of the day, much to my long suffering wifes mock disdain. Her usual phrase - happened about ten minutes ago - "Bathroom's free" tells me it's gonna be another late one.

The engines are now both assembled, tomorrow I'll take some pics and put them in 'Finished Projects' which I guess is where they should be.

Hope you've all enjoyed the journey - thanks again

Ramon
 

Don1966

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No Ramon, thank you for you generous and unselfish journey and posting your teaching for us. I am sure you have inspired many a forum fan here. I do understand about not getting started on anodizing no apology needed here. I will be looking in the finished section for your final video.

Best regards Don
 

dsquire

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Ramon said:
Hi guys, thanks for the response, nice to hear from you.
.
.
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Don, I did the anodising today which went well. I hope you won't mind but I don't really want to go into the process at this stage. I have an article which is due to be published fairly soon in ME describing my attempts so don't feel it would be fair to pre-empt it. Hope you understand. However I did post on here in reply to somones questions on it sometime ago - just the basics but enough to get the idea. Perhaps a search will bring it up

It's not a difficult process and it's certainly worth pursuing.....

Just remember to wear gloves when dyeing :)

We totally understand seeing as it is going to be published. Please let us know when it is published.

Well I think that really is it on this thread. Dave, Brian and all the others - I appreciate you taking the time to send thanks and respond. As the Waller engine thread and now this developed so the need to remember to take photos at all stages became a requirement more than just a personal record of some of the ops. You've seen just over 200 on this - there were well over 600 taken and the time to sit and go through them as well as post takes a fair bit of time - usually at the end of the day, much to my long suffering wifes mock disdain. Her usual phrase - happened about ten minutes ago - "Bathroom's free" tells me it's gonna be another late one.

I realize that it is a lot of work with the photo's and the writing and then having to organize it all so that it makes sense to someone that may not understand the process. I think that you have made a top rated job of it. I think that you deserve the gold.
!cid__cup.gif

The engines are now both assembled, tomorrow I'll take some pics and put them in 'Finished Projects' which I guess is where they should be.

I'll be watching for them Ramon

Hope you've all enjoyed the journey - thanks again

Ramon

I know that I have enjoyed watching this come together and look forward to your next project whenever and whatever it might be.

Cheers :)

Don
 

Ogaryd

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Hi Ramon,

Just wanted to thank you for your time and energy posting this build. I've learned so much.

All I can say about your engine is WOW. :bow:

Gary
 

vcutajar

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Thank you Ramon for the very detailed descriptions and photos.

Vince
 

Jasonb

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Thanks for another very informative build diary Ramon, its certainly going to come in handy on the firefly.

Can I ask where you get the 1000g lapping compound, I can source upto 600g quite easily but searches have so far drawn a blank on teh finer stuff or could a metal polish be used for the final lapping of piston to liner? I suspect the answer will be that you have had that little jar for years :)

Jason

PS Whats next ;)
 

Ramon

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Hi Guys - thanks as ever for all your kind comments, it's certainly nice to hear that the time spent is appreciated.

Thanks for understanding re the article - I don't know exactly when but it should not be too long.

Jason , I don't know a source these days, just as you suspect I have had mine for many years However ;D I also have some powder, more than enough to let you have some so send me a PM when you have a mo

Brian, (Runner) my apologies but I overlooked your question last night. The engine(s) were both started by a good old traditional flick. I would like to say I don't possess such a thing as a starter but that wouldn't be quite true - I bought one at a swapmeet last year for the boat - still haven't used it though. Personally I visualise the potential of doing so much damage with one that I much prefer the 'digital' method ;).


Drawings - ah the drawings. Some may have noticed I have not given much mention to them. Well after being so certain in the first instance that they were suitable for the download section I simply could not believe the discrepancies, errors and misssing information that they exhibited :-[. The Racers and the Etas were made from pencil drawings and whilst there was obviously the odd thing here or there there was nothing of the magnitude of these :-[ :-[. Talking about this with Sue - my embarrassment that is - she pointed out that they were done after I came out of hospital - hmmm maybe the anaesthetic played apart then. Well whatever, that's not an excuse but possibly a reason. I have though, as the anomalies presented themselves updated the drawings to 'as built'. I won't upload them now but should anyone want a copy I could easily send them the PDF files if they PM me.

Today was spent tidying up and taking it easy. I did run the second engine tonight - which performed as well as the first. Though there doesn't seem to be any leakage I still think a paper gasket needs fitting 'tween liner and case. Not possible today as my circle cutter has been put away somewhere safe and totally unaccessible - rather I can't bloody find it :D so it will have to wait until the weekend shopping trip to buy another when of couse after which I will ::).

I'll put some final pics of the finished engines over on the other thread.

Regards - Ramon
 

canadianhorsepower

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AH:eek: don't know what to say
I was knocked out when I saw this I broke my jaw when it hit the desk
 

gus

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Model Engineers' Workshop magazine 194 had a very good and instructive article on
"Home Anodising" .Never though it could done at home.Front page showed I.C. Aeromodel Engines beautifully done and dyed.

Much as i like to,there is no way I can go into it as most of the chemicals are controlled.They won't sell unless you have a license.License is given to an individual working for a company buying the restricted chemicals.The lincensee is held responsible for safe storage.
Years ago I had to apply for license to buy chemicals to make packing foam.Poor Gus gets fined for spillage.

Please post foto of your accomplishment. Congrats
 

Jasonb

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Gus, that article in MEW was written by Ramon!!

J
 

gus

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Gus, that article in MEW was written by Ramon!!

J


Ooops. I got so engrossed by the content,I missed out the author----Ramon.
I subscripe to both ME magazines.

The anodising and dye was so well done.Perhaps I try to find a way to buy the chemicals.
 

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