Steam Engine

First big metal project on the lathe, a small single cylinder single action wobbler engine, turned from solid brass. I wasn't working from plans, more just winged it with the materials I had in my shop. It stands about 4" high. Runs well on about 15psi of air, starts to shake above 40psi, and turns into walking device at about 80psi. Not the most balanced of engine designs. Fun to make though. See below for a video and construction photos.

Turning the flat on the piston. The heat shrink tubing you see is packing material, behind the brass piece are two lathe tool bits used to provide support and space the piece being turned away from the back of the chuck. I had to flatten one side so it would clear the crank at the bottom of the engine.

Finished piston next to the cylinder/column/crank assembly.

That little pin is what attaches the piston to the crank wheel.

Its press fit into place using a 2 ton arbor press. The trick is to turn the pin slightly oversize so it doesn't quite fit in the hole, then use the press to persuade it. I did the same thing with the crank shaft and flywheel.

Turning the column. I heard that turning a square into round on the lathe is supposed to be hard on the tooling but I found with a piece this small I just set the lathe to its slowest speed, and took lots of light cuts. I did manage to jam the bit once, but fortunately my lathe is belt driven so the belt slipped and didn't cause any damage.

Finished cylinder and column. Those two large extra holes on the side are where I miss drilled the column, they are now lubrication holes. The smaller hole is where the air supply/exhaust hooks up.

I added this chunk of brass to the bottom of the engine to stabilize it. It is attached with a single screw and a pair of alignment pins. Also gives me a good place to tap a couple holes for the mounting screws.

When I tapped the holes in the base I used the wrong tap. So after some swearing I realized that I could just make my own brass screws. here is one being parted off the lathe. I used a die to cut the threads. Once parted the slot at the top is cut with a hacksaw.