Inspired by Chuck's opposed 4, I decided that I would have a play with rotary porting to see what I could learn about timing. Half way through some experimenting, this idea of a test bed motor came from nowhere!
Building the bits.
Compressed air is supplied to the copper tube. I don't have steam but I am sure it would work.
The machining took about four hours and I then had a running motor. At 10 psi it runs at 2,000 rpm and at 20 psi it makes 5,500 rpm, I did not want to try it higher!
What did I learn? Rotary ports work easily and there is no need for extreem precision, stationary leakage is no problem. Timing is not that critical. Speed is best governed by restricting the exhaust.
Has anybody got anything to add about the design of rotary ports? Then I can get on with this next project.
In that case the material I used must have been bronze ! When I turned it I needed to hone the lathe tool because it seemed not to want to cut, the tool seemed worn and blunt. The swarf was little fine hair like strings and the tool left patterning when facing.to tell the difference between brass and bronze is simple. brass is yellow and hard and makes flaky chips when machined. everything else is bronze. imo brass is just one of the bronzes (copper alloys).
if your material makes stringy chips or makes continuous chips when drilled, or is darker than bright yellow, its bronze of some kind.