I had built numerous reciprocating engines out of legos before, some with two cylinders, each double acting. Legos is ideally suited for this sort of task. Building one out of wood seemed a logical next step. The engine I built was a single cylinder double acting engine. The valves is a specially carved out piece of hardwood sliding in an enclosure with other holes cut in it. Its nearest the camera in the picture, and actuated by the crankshaft in the middle. The main piston is the large thing in the back, which attaches to the large wheel.
For fun, I added some auxilary pulleys for stepping the rotational energy up or down, but the engine was never powerful enough to actually power anything - in large part due to blowby in the main cylinder. There is no seals in the piston, and it has to run freely even with low precision and wood warpage. It was very sensitive though - I could run it on 400 pascal, or about 4 cm of head when measured with water. It could only run on air - steam would have quickly swelled it and completely jammed it up.
I have since written a more detailed page about this air engine on my woodworking website.
As it turned out, if exercised long enough, every unit would eventually turn into a "bad unit". It was too late to fix the hardware design by that point, but the machine did allow us to better study the problem, and test a software workaround for it.
This isn't the only wooden machine I built for testing products at RIM. One of my other machines was the pager rotating machine
The neatest of these vehicles I ever built is the above wooden tractor. The tracks are block chains all made of wood. Each chain is independently powered by a VW bug wiper motor (perfect size and format for the job). This vehicle worked amazingly well, and thanks to most of the weight on one end, it turned very easily, and could climb even very soft and unstable surfaces, such as a pile of planer shavings. I was amazed by how well the chains worked, and by how much abuse they could take.
I have since written a more detailed page about this tracked vehicle on my woodworking website.
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