Bog's Paddleduck Engine

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kvom:
I think I have the crankshaft assembly sorted. Following some of the above suggestions, I removed the bearing blocks, keeping themn in order and attached to the drill rod. I placed them on the surface plate, and while pressing down on all 4 with one hand I was still able to turn the rod with finger pressure on the other. Assuming from this that the hole heights were sufficiently equal, my suspicions turned to the base plate. I deburred all 8 mounting holes and also around the sides of all of the plate openings. Then I placed the blocks onto the base plate, still with the drill through the bores, and placed a brick on top of the blocks. I was still able to turn the rod, so I felt that perhaps the problem was solved. I reassembled the entire crank assembly, tightened up all of the screws, and I am now able to turn the flywheel and everything else with finger pressure. :beer:

When I have time again, I will repeat the exercise with the edge finder on the mill to ensure that the crank assembly is parallel to the center line before reattaching the top.

Thanks to all for the advice. :thumbup:

kvom:
Short update:

Got it all together, and with a bit more fiddling got it to a point where the shaft turns under finger pressure in both directions. The piston throw is where it should be, but I resisted the urge to start adjusting the valves and the other tuning tasks, as I had limited time to see it through.

I will get to try to turn the columns on the CNC lathe at school tomorrow afternoon, and have spent quite some time writing the g-code to do so. It still isn't coming out the way I want, however.

kvom:
My first try at running failed. :scratch:

I went through the chapter on tuning, and as far as I can tell the various components are set as indicated. I tried to adjust the bottom with the engine assembled, but found that tightening the crank webs sufficiently was a problem. Having a set of T-handle allen wrenches would have been an advantage. So I removed the top to adjust the bottom. Of course, when I put it back together things were stickly again. Eventually, as usual, the issue is traced to the crosshead guide rods, which seem to have to be "just so". I decided to ignore the problem for the time being and removed one of the rods from each crosshead.

My bits of threaded rod connecting the valves to the eccentrics were too long, so I had to reduce the lengths to get the valves set in the indicated positions. Once that was done I screwed on the top caps and replaced the blanking plates.

Then I discovered that while the input barb for the engine is for 1/8" tubing, my regulator takes 1/4". Sp it was off to the local hardware looking for a reducer with different size barbs on each end. No luck there, so I came home intending to make one on the lathe. While rummaging in some storage drawers, I found a Schraider valve with 1/4" NP threads, so I decided to put that as the engine input and hook up the regulator used for filling tires. ::)

Since it takes two hands to maneuver the hose, I couldn't see everywhere the air was escaping (engine didn't turn whatsoever). I did see oil all over one of the joints between the block and the steam chest. I need to enlarge the holes in the blanking plates and shorten a couple of the screws to get a tighter seal. I'll also make a double barb connector so that I can run the air hands-free and try to see where the leaks are.

Any other ideas gratefully solicited.

Darren:
You seem to be struggling with getting this one going, sorry can't help as you are way, way further than I am with this build.
But I wish you luck....

I was only looking at mine tonight thinking tomorrow I must make some more bits.... :ddb:
My enthusiasm has been swayed by not being able to source material for the block, but I'm still looking....

Brass_Machine:
Kirk,

I have no suggestions as I haven't built this engine. So nothing technical from me... that said, for me, if I put something down I am having problems with and leave it alone for a few days... I find going back to it is like going back with fresh eyes.

Hope it helps

Eric

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