Occasionally I hear from others who have built the simple Stirling engine from my plans. Most people end up making some kind of modifications to the plans. That’s fine with me, in fact I enjoy seeing how other people solve a problem. The only area where experimentation could be risky (in terms of ending up with a running engine) is probably with the power piston and cylinder. Those two components need to achieve compression with very low friction. If you find a readily available and inexpensive piston and cylinder combination with low friction and decent compression please post a comment. Anything from 1/2 inch to 1.5 inches diameter would be useful. Of course if you have a lathe you can make an even closer tolerance piston from aluminum easily and it works well in the brass cylinder. I’ve also had good experiences with nylon pistons. My goal on the simple Stirling 1 engine was to design an engine that didn’t require a lathe or tapping, just a drill press, a hacksaw, and files.
Peter Gross in Tasmania built this engine with a few modification. Most notable are the use of a PVC displacer cylinder (ABS is apparently not readily available where he is) and the use of a CD to attach flywheel weights.
And some detail photos of his engine:
Peter Gross also offers this advice for cutting the brass tube for the piston, cylinder, and other small brass tubes:
1. Using a drill press, drill a hole exactly the same size as the tube OD in a small piece of wood (eg. 8x2x0.75″ dressed pine) then clamp the wood in a vice.
2. Push the tube through the timber to the required length then cut against the wood using a “junior” hacksaw with a sharp fine blade while holding the tube from the other side of the wood.
3. After cutting the end of the tube can be smoothed accurately using a fine file against the wood. This gives a nice square end on the tube without crushing it or cutting your fingers.
4. The wooden jig can be used many times by simply drilling extra holes of the required size. For the larger tubing sizes I used a hole saw.
Powered by dry ice
Ryan Proctor built this simple Stirling engine. The video shows it running backwards using dry ice. Ambient air becomes the heat source. Ryan later went on to design and build a larger Stirling engine as a college project.