Clausing runout in chuck, how to correct

Hi,

Went looking at a lathe today, had some drill rod and a dial guage with me so set it in the chuck and started it rotating. It was immediately obvious that there was some runtout and it was about 10 thousands of an inch. I checked up and down the bed and the runout was consistent so I know the chuck was parallel, the bed was in great shape, but again the chuck worried me. I played with it for a while, looked at the jaws but the error was consistent. The lathe hasn't seen much 'hard' work in its life apart from a lot of foam cutting for various mold making. Everything works and it's generally a very nice machine. The question is, what do you think would cause it and do you think a new chuck would solve the problem? Or does it need to be reground. To be honest the seller was hanging around and I would have liked to have spent some more time, he wasn't pushy just making me uncomfortable! Thanks

You can make a boring ring and regrind or turn the clamping surface. Before doing that you should see if it can be adjusted to center. That all depends on how it mounts to the spindle. If it is bolted try loosening the bolts and tapping it in before retightening the bolts.

Ben

Also make sure the jaws are matched correctly. They should be numbered and match the number on the Chuck.

Ben

Ben,

Thanks, after thinking about it I did some googling and found various explanations, then went to youtube and looked at the Keith Fenner and Tubalcain videos where they both regrind their jaws. My suspicion, again after thinking about it, and the condition of the rest of the machine is that it just needs some fine adjustment. Thanks.

Quote:

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Originally Posted by bhurts

Also make sure the jaws are matched correctly. They should be numbered and match the number on the Chuck.

Ben

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Ok, that is good to know.