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chiphead42
08-01-2004, 10:53 AM
Hello Folks
I am a hobbist with limited experience. I recently got a new 3 jaw & threaded backplate for my Atlas 12x36 lathe. Chuck made in India not great but thought I could make it useable. I have read the articles on this & other groups & in the mags. about mounting chucks. The chuck came
with 3 tapped holes, I drilled the plate to match & put set screws
against the bolts for adjustment.
Got chuck body within 1-2 thou. r/o. chucked 2" bar that I had turned earlier, 7-8 thou. r/o,chucked 3/4" bar same r/o. I used a die grunder mounted on tool post to try true up jaws. With chuck turning slow took light cuts until all jaws ground. R/o same as before, put ink on jaws, ground again 'till jaws clean now have 18-20 thou r/o. I can't see how this could happen I am stumped.
Any help will be much appreciated.
TIA chiphead42

Mike Burdick
08-01-2004, 11:51 AM
Did you "preload" the jaws before grinding?

If not, here's what I'm referring to:
http://www.loganact.com/tips/chuck-jaw.htm

A word of caution: BEFORE cutting and grinding on a chuck make sure you know exactly what the problem is. This is accomplished by doing testing in a very methodical and deliberate manner. In other words “look before you leap”! Thinking and measuring are cheap compared to buying a new chuck. Hey, the whole problem could have been a tiny chip or burr - you never know until you check for consistency of the measures.

Here's an example of how to mount a new chuck to your lathe:

http://www.lathes.co.uk/latheparts/page7.html

_______________________________


[This message has been edited by Mike Burdick (edited 08-02-2004).]

chiphead42
08-01-2004, 04:14 PM
Thanks Mike
I did not preload the chuck. I will make a fixture and do that, should solve the problem. chiphead42