Elmer's Oscillating Cylinder Engine #42

[Kim]

Those parts came out great!  It can be stressful to get a good symmetrical radius on a part like that, but your method seemed to work out quite well.

Kim

[RReid]

Those look really nice. Machining time is often 99% thinking and set-up and 1% cutting.

[90LX_Notch]

Excellent recovery Eric.

-Bob

[EricB]

Still working. I set the frame aside for now to make some of the bits that mount to it, starting with the bearings. Since I hate cutting stock by hand I set up a tiny cutoff saw on my lathe for the brass. Sherline's cross slide does not like to be clamped like this and is easy to distort and bind so tighten gently.

I realised I would need some sort of stop for my mill vise. After searching the web for answers I drilled and tapped both sides of the vise 10-32 and mounted a strap clamp. I changed that out for one with a threaded hole for a moveable stop and started on the bearings themselves. The mounting holes are drilled from the bottom almost to the top. When I get around to shaping the top the holes will be exposed.

Today I sized a block for the bearing bracket that supports the flywheel and stacked up all the parts to get a peek of what the finished engine will look like.

I have a brass round for the flywheel that I started for another project and cut undersize.

Eric

[RReid]

That looks like it's coming along really nicely, Eric. 

[EricB]

Almost done with the bearings. Shaped the tops today. The first cuts brought the ends down to finish size and exposed the mounting holes on all 4 blocks. Next most of the excess was removed from the tops.

To make the top curves I first setup the rotary table and indicated it in. Then I made a mandrel and mounted a block on the mill. I was wanting to make sure I had enough clearance between the headstock and the rotary table so I made it a little long, but I failed to consider the X travel limits of the mill. My setup needed another 1/4" to get to the end of the part. I shifted the mandrel in the chuck to get the clearance, but I probably could have just removed the stop screw from the mill table.

I did the first bearing in steps to find the depth I wanted and then cut the other three to full depth without changing the Z setting.

The finish of the curves did not come out as nice as others I've seen. I rubbed them with a scotch brite pad to make tham look a little better. I guess I'll need to use some sand paper on them.

One of the bearings needs a pair of studs to mount the steam inlet which I need to make first.

Eric

[Bearcar1]

You are doing some nice work there Eric. If I may suggest, make yourself up a set of filing buttons to assist you in cleaning up the tops of your bearing blocks, They are invaluable and will help keep the surfaces flat and the edges crisp.


BC1
Jim

[propforward]

Top notch work - really good work on making the top radii - a very difficult feature.

[crueby]

Another commonly used method to round over the tops of the caps is to clamp them in the mill vise, with a small piece of round rod or a drill bit under the cap as a spacer - take a pass with the mill, unclamp/rotate the cap slightly, press down on the cap onto the rod while clamping again, take another pass. Only needs 6 or 8 passes to round it off, gives good results, still can need a little filing or sanding to smooth over the little steps that are left, but its an easy setup.

[propforward]

That is a really neat trick. 

[EricB]

Thanks for all the comments. I'm having a good time solving the puzzles of how to make each part.

Jim, I was hoping to avoid making filing buttons but that's probably the best way to clean up the finishes.

Chris, I thought about using the method you've shown, but I paid a lot for that rotary table so I'm using it for everything!

I started working on the steam connection last night. For the inside head Elmer suggests using two pieces soldered together to "avoid making chips out of valuable metal."  This part is basically the same as the inside head but cut from a solid piece. Lots of chips!

Eric

[EricB]

Here is the rest of the steam connection work. It still needs a little more finishing, and the flange is a bit oversize. I need to get better about measuring.

Eric

Edit: I put it back in the chuck and worked the flange down to its proper size.

[propforward]

I paid a lot for that rotary table so I'm using it for everything!

I get that! 

Top shelf work you are doing - really nice parts. Very impressed.

[EricB]

I made the flywheel today. The brass round I had planned on using was much too large to turn into chips so I did some extreme parting from a smaller diameter chunk of stock using the mill. I know this is way past what I should have tried with such a little machine but it handled the load ok. The cut end looked horrible but so does a hacksaw cut.

I faced the sides and reduced the diameter also on the mill.

Not shown, I drilled and reamed the crank shaft bore and hogged out the sides using and end mill and the rotary table.

Finally I put it on the lathe, using the same mandrel I made for the outer radius on the bearings, and finished it to the size I wanted. I'm not sure if I'll cut some spokes, drill some holes, or leave it solid. I'll need to find a set screw to fix it to the crankshaft.

Eric

[RReid]

That flywheel look great, a nice finish on it. Good on you finding ways to make small tools do big jobs!