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Turbo,
I am doing the pivot pin and I just made one test piece from 1/4" dia. round and left it oversize 0.164 (I think) for now until I get your final dim. I would drill a test piece of scrap with the nearest drill size to see what dia. you get, and remember drill bits drill a little larger. If we go by the drawing your hole should be about 0.158 for the hole. Maybe find or make a scrap pin of 0.156 to use as a test for fit. 0.002 clearance should be about right for the pin to turn OK.
Paul (pjf134)
 
Turbo,

The bushings measure 0.378 to 0.379 on all samples. Try drilling a scrap piece with a 3/8" bit and see what you get. If we can get close to 0.390, the bushing should slip in. If anyone tries to force it in, they risk breaking the bushing. Too loose and there may not be enough support for the bushing if there is some force applied. (Oops, I dropped it.)

The bolt circle is 0.313" radius at 120*, as shown on the drawing.
 
Hawkeye,
Are you allowing .011 Clearance for the bushing? .379 to .390
Paul
 
Paul, You're right. That should have been 0.380.

B34VD, I was visualizing just that treatment. The bevel would look good. The mounting holes aren't dear to my heart. Moving them inland won't hurt.
 
Hawkeye,
I figured the 0.390 was a typo.
B34VD,
Bevel and hole location is OK with me.
Paul
 
CAD or trig, Turbo.



BTW, are you guys documenting all this with pictures? It would be nice for those of us on the sidelines.
 
Turbo,

I take it you don't have a rotary table? Your main bearing hole and the three mounting holes would be relatively easy with one. The most accurate or at least repeatable method without one would be to make a template out of 1/8" - 1/4" steel, measured as closely as you possibly can. Then drill pilots with a prick punch, a center punch and a #3 center drill, followed by your through hole.

Since you have 0.375 thick material, I'd suggest drilling through with your tap drill (or, in this case, a size smaller), then drilling part way through from the back side with a clearance bit for a #2-56 screw (around a #44 drill). We don't need threads all the way through - just around the same as the thickness of a nut for that bolt. The clearance hole will guide the tap to start it straight.
 
Seems there is a bolt circle layout table in the Machinery Handbook.
 
Mike,
Thanks for the info, now only if the other 2 parts get the same 0.250 we are in good shape.
Paul (pjf134)

What do you all want the ID of the flywheel to be? I planned on reaming to 0.2490"...

John
 
John,
The bearings that Hawkeye did comes in at 0.250" and the crank that Scrapmetal is doing I am not sure of the dimension. I was going to make the axle .250", but I am waiting for final dim's before I do them. 0.249 should be OK for press fit on axle, maybe just have to add a little heat to the crank and flywheel to get them on the axle. The bearing or axle might have to be worked to make it a running fit.
Paul
 
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