I was not excited with the engine running in single action mode. It required at least 50 psi to keep it running even though the engine seemed to turn over easily with no tight spots.
I was a bit suspicious of that crank web/flywheel combination. It was made from a 3” diameter x 1” thick piece of brass and at just over 2 pounds I thought it would be sufficient to do double duty.
I found a nice piece of scrap cast iron 0.7” thick x 3.5” diameter so I decided to make a “second” flywheel with it and see if engine performance improved. After facing both sides, I bored a central hole 0.750” diameter for fitting to a hub.
I turned a hub to fit this hole, then I drilled/reamed the hub ½” to fit the crankshaft. I drilled and tapped two 10-32 holes for set screws.
I fastened the hub to the flywheel with some Loctite and after curing, I drilled a 1/8” hole at the interface of the hub and flywheel. Then I put a 1/8” piece of brass with a drop of Loctite in the hole. After curing I milled most of the excess brass off, then faced to flywheel to finish it.
Now, with this second flywheel adding almost 2 pounds the engine runs slowly on 20 psi. It may be that doubling the scale requires a bit more mass in the flywheel. Once I get it to run in double action mode, the flywheel may be unnecessary.
Side view 1:
Back view :
Every engine seems to have its own peculiarities and this one is no exception. I double checked my valve slot dimension and it follows the plan OK. But the valve position has a very small arc in which the engine runs well in either direction. That made setting the valve for the first running a bit time consuming. I managed to get the reversing feature working but the valve position does not have a lot of “wiggle room”
There are two springs working in this engine. One of them holds the cylinder against the column. I think I have that one right because I’m not seeing many bubbles of oil coming out of that interface. So it’s strong enough to form the seal, but not so strong as to be a major source of friction. The other spring forces the valve against the column. I think that one is too weak since the valve often drifts off its optimum setting causing the engine to slow down. And note the oil spray in the back view around the valve. I’ll need to work on this.
Finally, I need to address the double acting feature. I may need to remake the packing gland since installing it introduces too much friction.
I should have this engine at Cabin Fever as a work-in-progress.