I just completed this engine and it runs! It is built from plans that were published by the Edelstaal Technical Institute in 1972. I downloaded them quite a while ago but I don't remeber the source. Based on the information in the booklet that came with them, this was a kit that was marketed to owners of Unimats. It has a 1/2 inch bore and a 5/8 inch stroke. So far I have been able to run it on 20 pounds of air pressure. All of the machining was done on a Smithy 3in1 machine. With the exception of the 3/16 CRS rod used for the columns and crankshaft and the brass tubing, all of the other materials were pieces of scrap of dubious parentage. The only real problem that I had was when I broke a tap in the final hole in the cylinder. I annealed the brass pipe and then bent it in a jig that I made out of wood. All in all, it was a fun project. I will post some pictures of the work while it was in progress and a video as soon as I learn more about how to use Photobucket and my camera.
I spend about two hours a day on this board and Home Model Engine and read all of the posts. I can't thank the people enough who have given their time and energy to these sites. I have learned so much. I feel both inspired and intimidated by the projects that I have seen. These are the best sources of information that I have found.
Thanks to all,
Jack
