Piston/Sleeve Resizing Die

[pre1960]

I have been intrigued with the process of piston/sleeve resizing that has been offered in the rc community. I had 3 done and was very pleased. Anyway,Being a jurneyman tool and die maker I kicked some die ideas around my head for quit afew months, got some freed up shop time, and exacuted on building the first revision. I was prepared with "two" worn out piston/sleeve sets,along with a brand new in the package set to compare with. I compressed both sleeves for snug fit at top stroke end point( 5 minutes effort ) fallowed by 10 minutes of hand lapping for optimume fit. I find that RB factory piston sleeve fits are tighter than Mugen MT12 so I went alittle tighter on one than the other. The tighter fits are harder to break in , though resulting in better performance and longivity. I completley measured / compared with new set / and documented sizing to conclude my shop efforts with project. That evenning I reassembeled MT12 engine and installed in XXX-NT for breakin and testing the morning fallowing. In short she was very easy starting, and I ideld engine for 1min, 5min, 15min,and 40 minute interviles , cooling for 10 minutes in between. Not a stall...burned over 260ml fuel...proboble the best break in expereanced to date . Engine did stall with first throttle response( expect some load up after over 1 hour at idel) fallowed with a easy restart. On the dirt for 10 minutes of short bursts throttle. Another cooling of 10 minutes....Then beat the living snot out of that Drake , for a half hour. Inspecting engine that night the compression was excelent. And no problems found at dissasembly. Finally, I am curious to weather the intermediate/addvanced RC hobbiest can perform this process, should I offer a user friendly tooling/ Die set that is afordable?????? Reply postings are incouraged. Serious emails are welcome. Regards,

 

[j0olz]

I also have a lot of experience using CNC machinery (lathes, mills) i was wondering if you could better explain this technique to all the new people out there who dont really understand exactly how you were doing it. I mean, they may think you were banging it with a hammer back into shape.

 

[FastEddy]

Originally posted by j0olz
I mean, they may think you were banging it with a hammer back into shape.

What no hammer?
I’m all for trying new things but got lost in the process description.
Please explain it to me like I'm a twelve year old, well maybe like I'm six.

 

[pre1960]

I can elaberate. The die set is of "two" parts, that could be held in one hand. The lower die holds the sleeve . The upper die guids the piston into lower die, compressing the sleeve bore inside diameter to smaller size for snug fit. With finger preasure you will no longer push piston thru top surface...Piston will become tight 1/16" or more from reaching top surface. I used a hydrolic press to push upper die ,holding and guiding piston intoo lower die. Cruedly, A heavy duty vise would be my second choice, and the rubber mallet the Third. Seriously, Should the next revision be for a end user , he may only need a vise and few hand tools. Please don't ask me for the print with tollerances.

 

[x_789]

I understand the concept Pre the ? I have is. If you are compressing the sleve wouldn't that mean the od of the sleve will now be smaller. wouldn't that cause the sleve to be loose in the case? Also doing this compression of the sleve does it cause any adverse effects as far as the orginal heat treatment to the sleve. Will it not just expand back to its origianl size after it gets hot a few times and then not recontract to the new smaller size? X

 

[pre1960]

Great questions! By theory the OD is affected along with the ID. We are talking 0.001" to 0.002" here....Less than a humman hair. This would have a adverse affect on engine as it expands and contracts, causing a fluctuating piston/sleeve fit,and compression varriation. The resizing I had done thru outsourse I seen a very minimal problem here that I eliminated by simply running my engines at cooler temps.....190-220 degrees . Personally , I don't trust a NIB fresh novarossi engine, freshly broke-in will have any longivity running over 220. But ...But...But, The result of the sleeves compressed in "My" Die, were with a tight fit in engine case at reassembly....Its all in the way the alloys/ molicuels flow and re construct. After running a few hours I dissasembled engine and re assembeled ,again with as tight a fit , requiring to be lightly assisted with rubber mallet. I will give a true prospective of sanerio here so keep the questions and coments going. Thanks!

 

[j0olz]

ok, now u got my goin. All u need to do now is post some pics of the process and tools. This process really is fascinating. I remember i used to do it at my work with some really complez tools and machining. Practically re milling an entire sleeve. This is a very simple process. POST PICS!!!!!

 

[pre1960]

Weather It takes me 1 week or 6 months, After a Die is debugged and put in production, It MUST provide for A "SIMPLE PROCESS"; And be highly productive, Concistant, and operator friendly. I will look into providing pics and vids . Regards,

 

[pre1960]

PISTON/SLEEVE RESIZING SERVICES IS AVAILABLE FOR THOSE INTERESTED IN OUR TOOLING ..... OR PERSONAL END USE. We will not squeeze ,pinch ,or bake your investment. Details will be made available in our WebPage, and will become available for viewing as approved by this and other website" adminastration approval.

 

[pre1960]

Webpage now ready for viewing: http://www.acsu.buffalo.edu/~jfroth/pinch/