Injected Diesel 56cc 2 Stroke, Will it ever work?"

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Hi Lloyd, I really admire your work!
I have a question for what might seem a potential issue, unless -of course - is not the complete design; which I believe is the case.
The link between cylinder liner and crank case, as seen in the picture, looks not that rigid and prone to cyclic bending during engine run. Will you add more reinforcements?
The nice part of any project is that only the owner has the final image of how it will look like. And it's a mix between design concept and methods to reach there.

I agree with you. Those 2 plates are 5mm 6061-T6 aluminum, but I think they will flex during operation. To fix that, there will be a cover plate with a flange machined into it such that screws will come thru the existing angled plates, into the cover plate, and lock the structure securely together. That plate will pilot over the snout of the crankshaft and support the bearings for the gear train. The gear train will have the main gear on the crankshaft, then up to an idler gear, then up thru another gear on the end of the camshaft on the right, then across to the left to the balance shaft, then again to the left to drive the roots blower at 2x overdrive. The location of the camshaft and the balance shaft will be a mirror image of each other, but will rotate in opposite directions. The camshaft and balance shaft will both have eccentric counterweights. The timing of the cam and balance shaft weights will be such that when the crankshaft counterweights are at the very bottom, the cam and balance shaft counterweights will be at the top. The crankshaft, camshaft, and balance shaft all rotate at the speed. That is how the 1-71 Detroit Diesel manual describes it, so I think it will work.
Thanks, Lloyd
 
(snip and high-lights by Lloyd)................................
The nice part of any project is that only the owner has the final image of how it will look like. And it's a mix between design concept and methods to reach there.

I was re-reading some posts and looked at your last sentence again in post #260. That is so true! 😍 When we have limitations in the tools and materials in our home shops, sometimes the "methods" play a much stronger role in the project. And sometimes the "method" is getting a tool to do something that it was never designed to do. Excellent observation.
Lloyd
 
July 6, 2024
Getting closer and closer.
I have added the odd shaped piece that is the crank cover and gear train plate. It is machined on the back side such that it has a flange on all edges to ( @NapierDeltic ) improve the rigidity of the assembly.
No gears are on it yet. I have set the head in place, along with the exh rockers to give a feel for what it will look like. The big ugly block on the left will become the cam shaft bearing block and also the lifter support. And on the right in a similar fashion will be the roots blower. The compartment at the bottom will house the pumps, etc.
Right now the beast is 11 kilos and 0.43 meters tall. I am glad I didn't have a serious weight or size goal. Just like budgets, they are a noble goal that is seldom met.
Engine-7-6-24.jpg
 
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But the .250" wall was a different animal. Not as pretty in the I.D. and there was a faint witness line from the ERW process, but the I.D measured right on the money. This time I started by honing the I.D. to 38mm, which meant removing only a few thou. I honed out nicely and the new 38mm rings fit nicely.

What do you use for honing tools in this diameter range?
 
What do you use for honing tools in this diameter range?
It's a brake cylinder hone I bought years ago at an autoparts store. It has one set of fine stones and will close down to about 19mm. I just chucked the liner in the lathe, protected everything as best I could with a bunch of rags, chucked the hone in the tailstock and manually moved the tailstock back and forth, while running at 300rpm. I used plenty of oil from a squirt can and stopped periodically to clean out the resulting slurry and mess. I clamped some stop blocks on the lathe bed to control how much the stones exited the ends of the bore, maybe 6mm. The stones are 28mm long.

It actually worked better than I expected. Moving the entire tailstock back and forth by hand, gently hitting the wooden stop blocks, made the process easy to control. I deburred the scavenging ports in the liner before I started honing. The large burrs probably would have messed up the hone.

If the finish is too smooth, some cloth can be used to build up a wooden dowel to the I.D. size of the liner, and them some 150 grit silicon carbide sandpaper taped around the cloth. Turn the lathe speed down and stroke the dowel and sandpaper just a few strokes and it will quickly add a nice cross hatch if that is your preference.

Lloyd

BrakeCylHone.jpg
 

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