Elmer's Oscillating Cylinder Engine #42

[propforward]

Looking really, really good. That slide valve is calling your name!

[EricB]

Getting closer to finished. Today I finished the bearing bracket, drilled and tapped the flywheel hub and installed the set screw, drilled oil passages in the tops of the bearings (though not called out in the bearing diagram they are shown in the overall diagram so I put them in), remade the thrust spacer for the crankshaft, and made a small pulley so the engine can do some work when its finished.

Still meditating on the slide valve.

Eric

[RReid]

Lookin' like an engine now. 

[EricB]

Is it just me, or does difficulty increase as the size of the part decreases?

This was a week of do I make a new part or can I salvage the mess I've just made.

I started with the rocker bracket. Looks simple enough. I figured I'd mill out the basic shape, drill some holes, and radius the ends. Easy! I don't even need to lay this one out, just clamp a bar of brass in the vise and start cutting. So I milled out the center carefully reading the hand wheels, then freed the part from the bar with a slitting saw. Perfect! Until I checked it against the diagram. Somehow it came out 1/4" too wide! Same as the diameter of the end mill I was using. OOPS!

Made a new one after carefully laying it out on the stock. Much better, but how do I hold it to drill the holes for the rocker shaft and keep them in line with the bracket? Maybe I should have done that first? Anyway I set it aside to think about while I made other mistakes.

My solution was to clamp my mill vise on its side and drill through that way. The two mounting holes were next, and I finished by milling the radii using the method Chris suggested on page 3 for the top radii of the bearings.

That's one.

Eric

[EricB]

The next part on the list was the valve itself. I had a cutoff piece from the rocker bracket that was the right size and had a machined surface to use for the port face so I clamped it in the vise and went to work. I was on the last pass cleaning up the end of the cutout and turned the hand wheel in the wrong direction to start the pass.

I figured the part was ruined but I went ahead and finished it anyway, missing the width of the slot for the valve rod by almost +.020". Maybe I can salvage this one.

Next was the valve rod. I had made one earlier when I was trying to decide how to taper the sides of the base, but I didn't use any support while turning it and it came out a mess. I also did not have a die to thread it with at the time. I made the new rod supported by the follower rest and finished it to final size with fine sand paper. Once the die arrived I cut the threads and drilled and milled the flats on the driving end. I used Sherline's dividing attachment for this. It's easier to setup than the rotary table. I had to improvise a machinist jack. I should make a proper one some day.

I made the valve nut to compensate for the mistakes I made with the valve. The gouge in the face shouldn't hinder operation but the slop arround the valve rod might. To solve that I made a boss on each side of the nut to take up the extra space. The nut was turned from 3/8" stock and shaped on the mill with the indexing head.

Hopefully all this will work.

Eric

[RReid]

"Experience" is just a shorter and more elegant way of saying "past mistakes". I think your valve fix is a good one and will work just fine. And I would argue that setting the vise on its side to drill the bracket is perfectly "right" way to do that job.

[EricB]

I was once told it was best to learn from other people's mistakes.

Here are some pictures of today's progress. I only have one more part to make and a bunch of finish work like dressing up the heads on all those little bolts.

Along with the rocker shaft crank I also made the pins for the small end of the crank, the valve rod, and the link pivot (mounted on the frame), and pressed them all in.

I need to start thinking about my next project. I have a PMR #3 in waiting. My wife suggested cleaning the garage.

Eric

[gary.a.ayres]

This looks great.

Am seriously thinking of giving this engine a go next (or at least a version of it), and if I do this thread of yours will be an excellent resource.

[EricB]

Thanks Gary!

In my original post I said I didn't think this design would be too complex. Well I missed the mark on that one. I was hoping to make something more interesting looking than a stack of blocks with a push rod sticking out. In that regard I think I succeeded. Here are the pictures of the engine with all the parts made and the final hardware in place. I'll let ya'll be the judges on if it's interesting looking.

There are a few parts I'm not pleased with. The fork that drives the valve rod is made according to the plans but somehow it looks out of place. I'll probably remake something with a bit more curve to it to replace it. The nuts for the steam connection are too large and the wrong material so I be making those again too. I'm also not convinced the solid flywheel is the right choice but I'm not ready to mess it up trying to cross out the center. I'll need to take it apart and clean up the finishes at some point too.

I don't plan on painting any of it but I will be mounting it to a wood base. Seems like the right thing to do.

To my surprize it actually runs with a little bit of air. What could be better than that?

Eric

[Flyboy Jim]

Good job Eric..........it looks great!  I'm betting that, if you let it age for a little while, you will end up being perfectly happy with how it looks now. 

Jim

[gary.a.ayres]

Yes - a beauty!

[MJM460]

Hi Eric, an interesting engine beautifully done. 

MJM460

P.S. Looking forward to the video!

[RReid]

Well done Eric, congratulations! Those first runs feel great don't they? Watch out though, they tend to set the addiction hook.

[EricB]

Here's a video. Sorry but all you can hear is my compressor.

<a href="https://www.youtube.com/watch?v=r7IdMiCZDrY" target="_blank">http://www.youtube.com/watch?v=r7IdMiCZDrY</a>

Eric

[crueby]

Runs great, looks great, nice and smooth.  Excellent!