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Drilling off-centre with boxford lathe! - how do I correct it?

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Bluechip:
Chris

I don't know whether this is relevant.

Nothing to do with headstock 3-jaw chucks, but I had a similar problem with the Myford, so I'll stick it in anyway.
I had a useless Chinese drill chuck with this fault. Don't know brand name 'cos it didn't have one.
Why doesn't that surprise me ?



Took ages to suss out what was wrong, it ain't obvious, but the 6JT socket was not axial. Not by much, but it made a hell of a difference.
Paricularly on small holes.It gave erratic results as the arbor can go in the tailstock at any angle. So, the error differs each time.

Dave BC

pabird:
Chris, if your 3-jaw is holding the part off center and you suspect that the jaws are incorrectly installed remove them and look for a stamped number on each. Install them in the chuck's slot with the same number. Now this is where I had a similar problem, my jaws were installed correctly but still wouldn't close and meet at the center of the chuck. I found that if I turned the chuck key backwards while putting slight pressure on the jaws with my other hand I could feel the scroll passing each jaw and the jaw would drop slightly. When the scroll passed the #1 jaw I could turn the chuck key in the normal way to close the chuck and the jaws would be in perfect alignment. Hope this helps. Smitty

Gerhard Olivier:
Chris simular problem mine was that the chuck just could not get any better than 0.84mm runout.  No solution ( that I could think of) other than to use slightly ovesize material and alway skim the surface to cut it concentrc then drill.  Problem with that is all work needs to be done in one setup. I re skimmed the backplate opened and cleaned the chuck checked jaws -  but mine does this with both external and internal jaws.

My conclusion was it is a rubbish chuck?????
gerhard

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