I realized that I don't have photos of all my engines on the web. So here they are. All the little engines I've made over the last 4 years.
Connecting rod model. This is a single acting model to show the connecting rod mechanism. The valving is done inside the bearing with the shaft.
Here is a wobbler model. This was my first engine. Valving is done by moving the entire piston so the ports align.
This is the largest layout so far. large 3" flywheel driven by two double acting pistons. It's not super smooth running due to defects in the valve box. I might go back some day and try again. I still need to string up the rope and belt to spin the generator at the far end, and build the governor.
This is a model of the Scotch Yoke to convert linear to rotary motion. It works well but is not balanced. Valving is again done in the bearing with the shaft.
I picked the Grasshopper because of all the unusual moving parts.It's actually pretty smooth and works well. single cylinder double acting with a home-cast 3" flywheel.
The latest engine. Designed to run in model boats. The valving is on top using an oscillating rod. Hard to get port alignment clean. I have a whole post about this engine posted earlier. Very smooth runner, in fact will run on lung power which is about 3-4 PSI!