Fits and Starts

I have managed to get crank attached to the crankshaft. A simple operation of you do it correctly or, in my case, not so much.

The drawings call for a press fit. This is where the shaft is about .001″ larger than the hole. You usually obtain it by using an “under” reamer, in this case a .124″ reamer to go with a .125″ shaft (O-1 drill rod). I had no such reamer and my choices were order a complete over/under set which seemed expensive or buy a single reamer for double the per/unit price of the set and a trip across town. So, of course, I opted for the third choice, use the nearest drill I had.

That turned out to be a #31 drill at .120″. Surely 5 thousandths is close enough for me to press a shaft in. Technically, I proved this to be true. Now if you specify that the shaft in question should not acquire a bend in it during the process then, no, I did not. It would not line up the holes in the flywheel bearing which is kind of the point.

I knocked the erstwhile shaft out with a punch and hammer and ordered the o/u reamer set like I should have done. I lucked out in that I did not have to remake the crank so I figured I should quit while I was ahead.

Here is the properly press fitted crankshaft in place.

Next I need to drill and tap for a set screw on the flywheel hub and then I think I will do the bits to connect the crank to the beam so I can see some bits moving together.

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