Fix for binding in 3-jaw chuck?

Aug 20, 2006 1 Replies
B

I have a Cushman 6" 3-jaw that I got at the dump. It fits a 10" Atlas. It had some superficial rust, so I broke it down and cleaned it. When I put it back together, the jaws bond in their slots. #'s 2 & 3 free up when the back plate is tightened up, but #1 still sticks. The sticking is such that it can't be moved by hand, but will move with taps from a dead-blow hammer.



I am about to put some valve grinding compound on the binding surface and lap it down. Is this the best way? I feel that if I try to use a stone I will remove metal where I shouldn't. Advise please.



Thanks, Bob


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B

Well, I went ahead and "lapped" in place. I did use Ajax instead of valve lapping compound. Quite a bit less aggressive. Cleaned it real well with "spirits" and then scrubbed with hot soapy water. Nice and smooth now.

I checked it with a DTI: .003 TIR. According to Teenut: "Standard 'accuracy' on non precision 3 jaw chucks is .003" TIR. This is found to be quite adequate for purposes for which a three jaw is properly used."

I'm happy, if a little guilty about not doing it "right". WTF, it's a dump chuck.

Thanks to all repliers, Bob

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