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gary hart
10-31-2007, 04:16 PM
Got an old 4 jaw chuck that use for holding larger work cause of its big hole behind the jaws. When all the jaws are snugged down daylight could be seen at the front of the jaws. Made for problems setting up a shaft and having it pointing parallel to lathe bed. Guess the chuck has had too much over tightening when work was held at jaw tips during its life.

Surface ground the jaws. Took jaws off and shimmed them out so the back of the jaws were tipped in a little and ground them.

Worked great, get good contact for full length of jaws now.

http://img.photobucket.com/albums/0903/ghart3/chuckjawgrinding.jpg

Forrest Addy
10-31-2007, 04:43 PM
Old four jaws make great Christmas tree stands, welding clamps, door stops, pendulum bobs for dynamic sculpture, mailbox ornaments, ballast, etc. No end to the applications. If you can resurrect an old four jaw by grinding out the bell mouth, more power to you.

miker
10-31-2007, 04:53 PM
Thanks for the post Gary. Is it neccessary to have them ground spot on parrallel or just at least biased to be gripping more toward the front??

Rgds

gary hart
10-31-2007, 07:07 PM
Michael, thinking gripping more to the front. Had first ground the jaws square to the chuck face but this made little change. Guessing the slot the jaws ride in are wore or metal displaced. Just guessed at amount to tilt, used double thickness of index card paper about .013"as a shim. Lucked out and the jaw prints left on piece of chucked up aluminum appeared same front to back on all jaws, so called it good.

oldtiffie
11-01-2007, 06:25 AM
Michael, thinking gripping more to the front. Had first ground the jaws square to the chuck face but this made little change. Guessing the slot the jaws ride in are wore or metal displaced. Just guessed at amount to tilt, used double thickness of index card paper about .013"as a shim. Lucked out and the jaw prints left on piece of chucked up aluminum appeared same front to back on all jaws, so called it good.

Thanks Gary.

Seems OK as you have allowed for the wear in the jaw guides.

Until I were sure that it was not case-hardened I'd be careful of taking too much more off.

Case-hardening, as the name suggests, is a means of hardening the outer layer/s to a high level of harness, which can cause brittleness if all through the job or in this case, chuck jaws. The inner part is not as hard but is very tough and resiliant.

On the other hand, the jaws may be hardened right through in which case, case-hardening is not an issue.

Nice job.