Elmer Verburg's
Open Column with Reverse
I'd looked at the plans for this engine a few times, but after seeing a completed model that someone else had made I had to try it.
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Always starting with what looks like it will be the toughest, the first thing I made was the bearing block.
A lot of mill work in this part. The air circuits are drilled holes that will be opened and closed by milled flats on the crankshaft. The crankshaft will act as the valve in this engine.
The picture above shows the crankshaft with the flats milled. It also shows the finished piston assembly with the shoulder bolt that will secure it. That bolt was critical and had to be made. The rest of the screws for the model were purchased.
There are three parts to the cylinder assembly, the air pipe, cylinder and base. All the parts are soldered together to complete it.
The reversing valve has two 1/16" milled slots in the back of it that will switch air flow to opposite flats on the crankshaft to make the engine run in either direction. The ball knob on the lever is a .177 BB drilled for the 1/16" diameter shaft.
Just a few more simple parts to complete the engine. The flywheel was made from 1" cold roll steel. The base is aluminum. The pillars are just 3/16" diameter brass, all cut to the same length, then drilled and tapped to accept 4-40 screws. The last part is the air inlet. It's just a piece of 3/16 brass turned down to .118" at one end, and threaded 4-40 to screw into the inlet hole in the block. It has a 1/16" hole drilled through it for flow.
A dozen 4-40 screws and it's done.
Great little model to build! It ran on the first attempt.
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In assembling the engine the steam pipe kinked. I couldn't live with that, so I made another pipe to replace it. These pictures are of the final model. I should make a wooden base for this one, but I probably never will...
For a copy of the plans Click Here
