There´s another build of a very similar thing atm in HMEM, by max corrigan. Far be it from me to try to steal anyone´s thunder, I´ll post my widget here. It´s perhaps also more appropriate here, since I modded the original design to suit what material I had in hand, and to get an even faster runner. These things run real fast, given a pressure of some 50-60 psi (4-5 bar).
side view
As you can see, it has a simpler linkage between the eccentric and valve, to not to rob power in the linkage mechanism. The valve, which is a 8 mm stainless bar with two milled flats, does not really rotate, it swings back and forth in some 75-80 degree arc, like a windshield wiper axle. A lot faster, though.
Also note the "intake manifold", far simpler than in max corrigan´s engine. It´s just a flat brass bar with a milled cavity inside, to furnish air (steam) to the cylinders.
The puny flywheel has an alum. center and a press-fit bronze ring around, to give some swing mass to it. Way cheaper than a full bronze/brass disk (miser, miser)...
There´s also interference-fit bronze liners in the cylinders, similar to Rudy Kouhoupt´s compound engine, from which I copied the idea. I built that before this gadget, and bronze liners work real well with alum. pistons. The pistons have grooves (one each) filled with graphite yarn, also suggested by Rudy K. I´ve used also (plumber´s) teflon tape for similar purposes, it´s a good alternative. Graphite is way dirtier, though
Another thing you can´t see are ball bearings, they make for a very freely rotating engine. It turns 3 full rotations at a flick of a finger.
You might notice also the "balanced" crank cheeks, the plans call for round disks. They´re not really balanced, but I first made them round, and the machine walked right off the table when I gave it some compressed air. So I cut big chunks off both sides of the crank pins, and now at slow speeds anyways, it stays on the table without clamps or screws.
I´ll try posting a video sometime soon, running on compressed air, I don´t have a steam boiler. But I don´t see any reason why it wouldn´t run on steam as well. The only possible rusting parts are the ball bearings and the fly wheel attaching screw. All other steel parts are stainless.
As a side note, I attached this to a hard disk spindle motor, running as a generator. Old hard disks ran at 5000-something rpm, and used 12 V for the spindle. To run one as a generator, you must give it at least the same 5000 rpm, and not expect anything like 12 V back, more like 4-5 V, if that. They must run very fast indeed to get
12 V, I´d say well over 10 000 rpm, but that´s just a guess
And the amps are very meager, just some mA´s.
I have a good stock of huge 10 mm LED´s that need at least 1.8 V to give any light, with a 1.5 V battery there´s no emission at all. I connected one of those to the HD motor/generator and gave the engine some (= a lot of) air. To my surprise, the LED lit up, flickering (the HD generator put out AC), but VERY bright, and after some 5-10 seconds it went off, never to light up again. Hm. I connected 3 LEDs in series, gave gas again, and I had 3 LEDs flickering
That wasn´t for very long, though (several minutes), the engine would need oil (WD-40), and there´s no provision for it when running. But it was nice to see anyway
