1" Bore x 1" Stroke Vertical I.C.

[Brian Rupnow]

Well, I must say---that worked out even better than I thought it was going to do. The radius on both sides only took a few minutes. Now I'll press that shaft out and loctite a shaft in the other hole so I can finish the machining at that end.

[crueby]

Wow - lotsa progress!   

[Brian Rupnow]

I can't believe how well this turned out. Machining these bosses qualifies as "something I hadn't done before". Tomorrow there are about 13 or 15 holes to be added (most of them tapped). I haven't got the ball bearings yet, but they are supposed to arrive tomorrow. I don't want to separate the pieces, get all set up to bore the cavities in my 4 jaw chuck lathe, and then not have the bearings. Since there are major cavities to be bored in both halves, I have to try and decide if I should drill and tap all the holes I can now, and put up with interrupted cuts while I'm boring the major cavities, or wait until after I have bored the major cavities to put in all the threaded holes. Probably the second option makes more sense, and I do have other parts I can be working on while I wait for the bearings.

[Brian Rupnow]

I have enough aluminum plate and steel ring to make a two piece flywheel. Of course, this lets me fool around a bit with the design. I kind of like this. The outer steel rim would be attached to the aluminum center with steel pins which extend thru the steel flywheel into the aluminum spokes. The heads of the pins might be visible where they extend thru the outside diameter of the flywheel, then get machined flush or I might even make them from brass and let them be a design feature.

[Brian Rupnow]

Now I need some help. I am searching for a 4 or 5 blade plastic fan or propeller that is 1.375" to 1.5" outside diameter.  I'm not too concerned about the shaft size because I can make my shaft to suit. I would like to source it in North America, I don't care where it is made. I spent half an hour Googling nd couldn't find one. I want to use it as a cooling fan on this engine and I don't have room for anything larger in diameter. Does anyone have a source or a link?---Brian

[crueby]

Take a look at the Graupner and Dumas RC boat props, they make both brass and plastic props in that size range.
https://www.ebay.com/b/Dumas-Hobby-RC-Model-Vehicle-Body-Propellers-Blades/182203/bn_105904918
They can be mounted on a shaft and turned down on the lathe (light cuts) to get them to a square-ended blade, like would fit in a duct pipe, and the shaft hole can be bored out to suit.

[Jasonb]

Can't you just cut one from some thin sheet and give each blade a twist, that's how I did then on the Thomson and RMC

[Brian Rupnow]

This morning yielded a flywheel made of pieces from my "left over bits" bin. The outer rim is mild steel heavy wall tube and the web and inner hub are turned from a single piece of aluminum. The web is deeply offset on one side so that when mounted the flywheel hides most of the ignition points. I still have holes to cut on the aluminum part, but I wanted to be working on something until my ball bearings arrived in Barrie. I just got a call that they are in, so I will put on my Covid Hazmat suit and be off downtown to Canadian Bearings to pick them up.

[Brian Rupnow]

We got bearings!!

[Brian Rupnow]

Okay---that's enough fun for one day. I kind of like the flywheel.

[Brian Rupnow]

 My plan is to drill 1/8" diameter holes around the outer ring and the inner web and Loctite 1/8" dowel pins into place on the center of the web, as shown. That may be subject to a bit of change, but not much. I don't really want to weld anything because of heat distortion, but I may make the 1/8" pins a from brass and a bit longer than necessary and then turn the o.d. of the outer ring so that all that really can be seen it two round brass dots at each web spoke.

[crueby]

Very neat solution!  In looking at the picture of the flywheel/web so far, I had originally thought it was all one piece. Watching along...

 

[Brian Rupnow]

The round piece of aluminum was 3.50" in diameter. The inside of the heavy wall tube cleaned up at 3.428" diameter. I put in a 3.50 countebore for the aluminum web to set up against.

[Craig DeShong]

I like the flywheel 

  

[Brian Rupnow]

Hi Craig---Glad you stopped by!! Today was the day to start counterboring the crank-cases. In this view, you can see that I have the counterbore for the 3/8" crankshaft bearing in place (It's a really deep one), and the large counterbore for the crankshaft, con-rod, and balance weights. There will be a second set-up in the 4 jaw to put in the counterbore for the camshaft bearings and cam. I would have been finished this side except that I had to take good wife down street to pick up a new microwave oven. In this horrible Covid winter, almost anything is a good reason to get out of the house.