[TODD KOLLMAN]

Anybody Got Any Ideas To Combat Part Lift On A Sliding Jaw Chuck?

[HuFlungDung]

Remachine the chuck jaws?

Use a tailcenter.

Reduce overhang.

Reduce depth of cut.

Reduce feed.

Machine a stop plate to go against the spindle nose, but fit snugly inside the chuck. This will allow you to dead end a certain range of parts against a stop and prevent push-through. You can be imaginative and add a threaded stop bolt in such a plate, to increase the useful range.

[TODD KOLLMAN]

Thanks for the input, but what I am trying to overcome is the lifting action of the jaws due to the sliding master clearance(combined with the jaw/bolt distortion from chucking). Wondered if anybody had come up with a jaw design that incorporated a pullback feature.

[Hogger]

Are we talking soft jaws on a 3 jaw lathe chuck? If so I've found that boring the jaws on a taper so they get bigger in dia. closer to the chuck will help get better part contact at high chuck pressure, especially with longer jaws, .001 per inch is a pretty good starting point, then when you clamp the part start clamping it lightly so that the jaws only contact at the outer tips, then increase the pressure untill the rear of the jaws make contact, if you get full contact at too low a pressure then rebore with more taper per inch. And always use a chucking ring at the rear of the jaws if you want accuracy.

[TODD KOLLMAN]

Thanks,
That actually was my next move but haven't done it yet. One thing that has helped to a degree is to insert a fairly hard piece of rubber or urethane inside the jaws below the part. The jaws grip the rubber first taking up all the clearance prior to gripping the part.