First project on the South Bend

RWanke

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Aug 23, 2017
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I actually made my first useful project on the lathe today. I did not have a chuck key for my 3 jaw so I made one and did it the hard way. I don't have a mill so I took a piece of 3/4" dia. 12L14 stock and drilled and reamed a hole about 3" deep in it. I then took a piece of key stock and turned 3" of it to be about .001 oversized of the hole in the round stock. Heated the the round in the oven and stuck the key stock in the freezer. Had to use a little hammer persuasion to get it all the way in but I think it will be there for good. Chucked it back up in the lathe and cut a taper on the key end then drilled and reamed the hole for the T handle. Took a piece of 5/16 stock and turned down each end and threaded (with a die) to fit a 10-32 nylock nut. Pleased with the way it came out

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Very nice. If the key-stock start to slip, just drill a hole through the round body and put a pin through it.

Hope you had fun.

Ray
 
Oops. Guess I really should have posted this in the projects area.
 
I thought about that but I'll be really surprised if it slips. It was heated to a straw color (I'm guessing 425-450) and the key part, that had been in the freezer for about 30 minutes, went in about 3/4 way before it started to seize. It took a thorough hammering to get it the rest the way in. Enough so that it mushroomed the square part of the key enough that I had to file it back square.
 
With a shrink fit, the allowance should be only .001 per inch of diameter, same as for a press fit. The act of putting the male part in the freezer would not be much help due to the small amount of temperature difference between ambient and the temp. in the freezer. You could have heated the female part to blue or black heat, and with the correct fit, likely you would have had no problem in assembling it.
Due to the fact that a shrink fit does not smear over the tool marks as does a press fit, a shrink fit has around 5 times the holding power than the press fit.
 
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