What is the preferred material to fabricate piston rings out of? I know of lots of people using viton o rings, but when looking at those the places that sell them say they should not be used on steam or water. There are also lots of people saying cast iron, but then comes the issue of finding a source for it. I kind of like the idea of using plastics. Has anyone ever used ptfe/delrin/nylon? Have you ever heard of someone 3d printing piston rings out of ABS? Another thought was using pvc as it is pretty easy to come by.
I saw a photo of a green twin oscillating steam engine on the Preston Services website a few years ago, and a Canadian buddy of mine challenged me to make one. Long story short, I built a foundry, used a 3D modeling program to model the engine using 3 photos, made the patterns, and cast the parts for a 60% scale engine. I recently got the engine running, and it can be viewed here: https://www.youtube.com/watch?v=UxIZ4iuhLyM The plan at this point is to finish the painting work on the engine, and publish it in Live Steam and Outdoor Railroading magazine. It was a long journey to learn the foundry work, but I was able to cast some of the parts in gray iron, with the remainder being cast in 356 aluminum.