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| Compressed Air 3 cylinder radial engines |
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| cfellows:
I saw Nick Muller's 3 cylinder radial engine several weeks ago on another forum 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. Chuck |
| cfellows:
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). Chuck |
| cfellows:
I completed the heads and began work on the body casting today. My fixture isn't very fancy, but it's all I had and worked find. I bored the opening for the cylinder with 1/4", then 3/8", then 1/2" end mills going very slowly. I finished the bore diameter to 9/16 using a boring head. Nick's castings are pretty accurate so no special fixtures were needed. The cylinder clamping ring seems kind of fragile, so I was slow and cautious drilling, splitting, and tapping it. I drilled the crankshaft bore out to 7/32" and Loctited in a 7/32" OD x 3/16" ID brass tube. I figured that would make better bearing material for the crankshaft. Next, I'll start the crankshaft... Chuck |
| cfellows:
Today I finished the connecting rods and the pistons. I made the rods out of 1/4" x 3/16" aluminum, the milled the crankshaft ends to overlap each other. Chuck |
| Divided he ad:
Looks like you've got this one well under way Chuck :thumbup: Interesting to see your workholding set-ups. Logged for use someday in the future :) Waiting for the next instalment :coffee: Ralph. |
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