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3 Cylinder Radial Compressed Air Engine

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I saw Nick Muller's 3 cylinder radial engine several weeks ago and asked him if he would be willing to sell me one of the castings.  He graciously agreed to and yesterday the casting arrived via US Mail.  There was no glaring evidence that the package had been opened by customs and, so far at least, no invoice from the Post Office or Customs Office for any fees or duties.

The casting was nicely done although it did require some cleanup with a file to remove flashing and smooth some of the edges.  Here is a photo of the casting mounted over the 3" 3-jaw chuck on my 7" minilathe. 

Not the best work-holding method, but by taking light cuts and slow feeds, I was able to face off and turn down the outer end.  I also drilled out the center hole for the crankshaft, starting with 1/8", followed by 5/32", and finishing up with 3/16". 

I plan to mostly follow Nick's plans but want to incorporate my slave exhaust valve in the head, so the top end will be quite different.  My head design won't be quite as nice looking as Nick's, but I can't use my slave valve with his design... bummer.


Will be following Chuck.


Wow Chuck....i hope you at leasr stopped long enough after the fairbanks to take a breath :) Will look forward to following along on this one too!!


I, for sure, will be following too!

I don't remove flash, because I know everyone has his own opinions how things have to look afterwards.
Chuck, what you did was the most critical machining, but you mastered it! I have ruined a few castings at that step. :)


Thanks, folks, gotta keep making some chips while I'm fussing with the paint job on the Fairbanks. 

I made a prototype of the cylinder.  I also made the head as an integral just because I could and it simplifies things (if it works).

The piece was made from a 1 1/8" length of 3/4" diameter brass round.  The bore is 7/16".  The cuts for the fins are .060" deep and the diameter of the bottom which will slide into the casting is 9/16" diameter. The side with the small hole will face the front of the engine where the compressed air will be admitted with a tube, much like Nick's design.  The large hole, then, will face the rear.  The slave exhaust ball bearing and spring will be inserted from this end and will serve as the exhaust port.  This obviates the need for an exhaust port in the crankshaft, simplifying construction and reducing the air leakage (hopefully).



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