Compressed Air Radial Engine

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cfellows:
Today I got started opening up the timing gear cover. Milling, filing and sanding are not my favorite operations, but it did turn out OK.

Here you can where I've got the back part of the crankcase in a 4 jaw chuck on a rotary table. I'm using a 1/4", 2 flute end mill to do the hogging, taking .050" per pass.

Here you can see the whole lash-up.

For the last pass of the cut, I've switched to a ball end mill to give me a radius at the bottom.

Here I've moved over and am cutting out the waste on the other side.

I've finished up all the work with the end mill.

Several operations later, I've removed the rest of the waste, and filed and sanded to get it prettied up.

The next series of pictures shows the part on the engine in various positions so you can kind of see what it's going to look like.

Still have a little refining and tuning to do, then I'll get on with cam...

Chuck

Bogstandard:
That is coming along just great Chuck, it sure is a long way from the original poppet valve concept.

You have really brought it along over the years. What next, a V-8.

John

cfellows:

--- Quote from: bogstandard on February 24, 2011, 05:06:32 PM ---That is coming along just great Chuck, it sure is a long way from the original poppet valve concept.

You have really brought it along over the years. What next, a V-8.

John

--- End quote ---

Thanks, John... Funny you should mention a V-8, I've been thinking about it, or maybe a V-6 just to be different. I've also been thinking about about an inline 6 and a straight 8. I think either of those would also be a pretty interesting engine.

In my earlier years of model building, all the emphasis was on getting the engine to run and looks were secondary. But these engines spend a lot of time in the display case not running but I still look at them every day. So, I've kind of learned that it's important to make them look interesting and "pretty" when they are just sitting there. So now I spend a lot more time trying to make them look like the real thing, just smaller.

Chuck

cfellows:
Tonight I made the cam for my radial. I was able to use my new rotary mounted chuck and it worked great. The cam is made from a 1.125" diameter brass disk about 5/32" thick. The lobes of the cam extend 1/16" so the disk diameter that is left is 1" diameter. In this first picture I have started cutting the disk. I advanced the disk .030" into the cutter, then turned the chuck with 28 turns of the crank. This rotated the cam 140 degrees. Then I raised the cutter above the work and turned the crank another 8 turns, rotating the the disk 40 degrees before lowering the cutter back into the disk. Then I repeated the procedure to cut the other half of the cam. I made two more passes advancing the part .020" then another .015" for the final pass.

Here is a picture of the whole setup:

Here is a picture of the arbor setup I used to hold the disk for milling:

Here is the timing gear and cam setup as it will sit in the engine:

I still have to round off the cam lobe tips and fasten the cam to the final gear in the gear train. I will probably cut a radiused slot in the cam disk so I will have some timing adjustment available to me.

Chuck

cfellows:
After a week of being sick and a couple of weeks working on projects deemed higher priority by the chief financial officer, I finally got some work done on this engine. I completed the profile on the cam disk, attached it to the final timing gear and made and fitted the valve lifters. Running the assembly with my drill proved it to be a smooth working assembly. I think this part is going to be particularly interesting to watch when the engine is running slow.

Chuck

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