3 Cylinder Radial Compressed Air Engine

[cfellows]

I saw Nick Muller's 3 cylinder radial engine several weeks ago and asked him if he would be willing to sell me one of the castings.  He graciously agreed to and yesterday the casting arrived via US Mail.  There was no glaring evidence that the package had been opened by customs and, so far at least, no invoice from the Post Office or Customs Office for any fees or duties.

The casting was nicely done although it did require some cleanup with a file to remove flashing and smooth some of the edges.  Here is a photo of the casting mounted over the 3" 3-jaw chuck on my 7" minilathe. 



Not the best work-holding method, but by taking light cuts and slow feeds, I was able to face off and turn down the outer end.  I also drilled out the center hole for the crankshaft, starting with 1/8", followed by 5/32", and finishing up with 3/16". 

I plan to mostly follow Nick's plans but want to incorporate my slave exhaust valve in the head, so the top end will be quite different.  My head design won't be quite as nice looking as Nick's, but I can't use my slave valve with his design... bummer.

Chuck

[vcutajar]

Will be following Chuck.

Vince

[b.lindsey]

Wow Chuck....i hope you at leasr stopped long enough after the fairbanks to take a breath Will look forward to following along on this one too!!

Bill

[MuellerNick]

I, for sure, will be following too!


I don't remove flash, because I know everyone has his own opinions how things have to look afterwards.
Chuck, what you did was the most critical machining, but you mastered it! I have ruined a few castings at that step.


Nick

[cfellows]

Thanks, folks, gotta keep making some chips while I'm fussing with the paint job on the Fairbanks. 

I made a prototype of the cylinder.  I also made the head as an integral just because I could and it simplifies things (if it works).









The piece was made from a 1 1/8" length of 3/4" diameter brass round.  The bore is 7/16".  The cuts for the fins are .060" deep and the diameter of the bottom which will slide into the casting is 9/16" diameter. The side with the small hole will face the front of the engine where the compressed air will be admitted with a tube, much like Nick's design.  The large hole, then, will face the rear.  The slave exhaust ball bearing and spring will be inserted from this end and will serve as the exhaust port.  This obviates the need for an exhaust port in the crankshaft, simplifying construction and reducing the air leakage (hopefully).

Chuck

[b.lindsey]

Chuck, is that cylinder sitting on a pink granite surface plate or the wifes countertop. If the former i am jealous

Bill

[cfellows]

Chuck, is that cylinder sitting on a pink granite surface plate or the wifes countertop. If the former i am jealous

Bill

It's the wife's kitchen counter top, but now that you mention it, I don't see why I couldn't use it as a surface plate...  as long as she didn't catch me! 

[Tennessee Whiskey]

Just don't wipe it down with WD40 when you finish, it's a dead give away

Eric

[Don1966]

Chuck are you going to take a breather bud, you burning the candles at both ends here. 
Well you are certainly off to a good start anyway.

Don

[Swifty]

Chuck, you get more done in a day than I get done in a month. My wife is happy that I have a hobby, but within reasonable limits, your wife must be very supportive or just wants you out from underfoot.

Paul.

[cfellows]

Well, I am retired and we have the house pretty much set up the way we want it.  We don't travel or entertain and my wife has her social groups and the grandkids that keep her busy.  So, other than chores like yard work, taking out the trash, etc., I'm pretty much free to do what I want.  Actually, lack of energy keeps me out of the shop more than anything.  I could have been out in the garage making the other two cylinders for this engine but instead I spent the afternoon and evening putzing around on the computer and watching TV.  Sitting in my Lazyboy with my laptop cruising the internet consumes at least 3 or 4 hours every day.  But, in fairness, it is usually educational and hobby related stuff.

Chuck

[MuellerNick]

I just thought, that it might be a nice addition to my plans, if I include your slave valve system as an alternative.
If you allow, Chuck!


So that would be a modified crankshaft and a new cylinder head with the valves.


Nick

[cfellows]

I just thought, that it might be a nice addition to my plans, if I include your slave valve system as an alternative.
If you allow, Chuck!

So that would be a modified crankshaft and a new cylinder head with the valves.

Nick

Sure, Nick.  Feel free to include it in your plans.  I made the head and cylinder as one piece, but it should be easy enough to make the head separate from the cylinder. Attached is a rough drawing with the dimensions I used on my version.

Chuck

[cfellows]

I completed the heads and began work on the body casting today.  My fixture isn't very fancy, but it's all I had and worked find.





I bored the opening for the cylinder with 1/4", then 3/8", then 1/2" end mills going very slowly.  I finished the bore diameter to 9/16 using a boring head.  Nick's castings are pretty accurate so no special fixtures were needed.  The cylinder clamping ring seems kind of fragile, so I was slow and cautious drilling, splitting, and tapping it.





I drilled the crankshaft bore out to 7/32" and Loctited in a 7/32" OD x 3/16" ID brass tube.  I figured that would make better bearing material for the crankshaft.

Next, I'll start the crankshaft...

Chuck

[Don1966]

You go chuck, Looking good bud. Dang your making headway. 

Don