I started to turn some knobs today, put a piece of blackwood that I had turned round between centers in the pin jaws on my Nova G3. Right away I noticed a lot of runout on the piece. It's been ages since I had used those jaws so don't remember if I had the issue before.

Dug out an indicator and magnetic base to do some investigation. The OD of the chuck had about .002" runout, respectable I think. I put the shank of a 1/2" drill bit in the jaws and ran the indicator on the remaining full round (the pic looks like the indicator is dropping into the flute but it's not) part of the shank. Runout was .010" right in front of the jaws. I removed the chuck and checked the spindle on the 3520B--zero runout on the shoulder right in front of the bearing.

So pulled the jaws off the G3 and put them on a G2 that is threaded for the spindle, not an insert chuck as the G3 is. Runout on the OD was .003, the drill was exactly the same .010" runout.

I don't know what is acceptable but when I can see runout on a chucked part it seems to me that's too much. What should one expect? Looking around the internet I find numbers for spindle runout but not chuck jaws.

Thanks, Gary

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