Well, spent some time in the shop today and made a little headway on the compressor. It was one of those days when I did a little "machinist dancing", you know, one step forward and two steps back.
I welded up the air tank for the compressor. Apparently I didn't do enough prep on the steel as I ended up chasing some air leaks around. It seems that once you have a dirty weld, it is really hard to clean it up and weld over it without just moving the leak. I finally peaned the last little pin hole leak with a ball pean hammer and that stopped it.
The next challenge was to make a small check valve that would be located on the tank. That would take some pressure off the compressor. I modified a couple compression fittings and made a brass sleeve that was soldered between them. A 7/32 diameter ball bearing was use for the check.
To test out the compressor I belted it up to an electric motor. This probably run the compressor a little faster than the model engineswill run. I had only one piston ring on hand so the efficiency is probably down a little. I'll add another later. I also ran the compressor without any oil for this try out. It pumped up to about 20 psi but wouldn't go any higher.