Homemade Stainless Steel Hot-Air Engine


| July/August 1993



hot air engine

After the initial success of the first engine, it seemed like a good idea to make another engine - bigger and better.

I started collecting antique engines about 1984, after I attended a Pioneer Day Celebration at Barberville, Florida. Those old engines fascinated me, and I decided that this would be an interesting hobby.

Eventually I bought, sold or traded some 25 engines. Since I didn't have much space in my garage, it was necessary to trade or sell some to get more interesting ones. It was soon evident that all these heavy 'toys' were getting too difficult to handle.

About this time a friend of mine, Alan Phillips, gave me some reprint catalogs of early Sterling Cycle engines. After reading this literature I decided that I must have a hot air engine. Unfortunately, none could be found locally. The only course of action left was to construct my own. The only information available was several cut-away views in the reprinted catalogs, so this is where I started.

Fortunately, I had previously taken a very comprehensive welding course at the local community college. For some reason or other my fascination with working with stainless steel led me to try to make a model of stainless steel. My first attempt took approximately three hundred hours. Of course, since it was a trial and error operation, it goes without saying that I ended up making several parts more than once! The first power piston was not properly sized in relation to the displacer. The little engine tried to run but just couldn't get going. Dilemma-make it bigger or smaller? On a hunch, I made it smaller and the engine ran. Success at last, what a rush!

I polished all the parts and took the engine to Zolfo Springs, where it was a hit. Lots of offers to buy, but when you put so much effort into something, you don't want to part with it for any amount of money.

After this initial success it seemed like a good idea to make another engine-bigger and better. So, back to the shop and engine number two began to take shape. This one is also stainless steel and has precision ball bearings in the rod ends as well as the main shaft. The first engine had needle bearings for the main shaft and pins for all the rod connections. As I was now an 'experienced' hot air engine builder, this one took only about half the time to complete. I finished this one by bead blasting to get a nice satin finish.