View Full Version : Anyone tried grinding jaws of a DRILL chuck?

J Tiers
07-08-2010, 10:04 PM
The brilliant bulbs at work have managed to score up the jaws of the "CF" brand 16mm chuck I put on the DP at work (my chuck, put on in self defense, as I sometimes need to drill a hole)

As a result, drills in it wobble, although the runout of the chuck body is only a matter of 0.1mm. 10mm from the jaws, it is more like 0.5mm, which is way too much.

I figure there may be a way to grind the jaws true again, since I am NOT going to replace it, and I doubt I could get jaws for it.....

Anyone done it?

Got any good tips on doing it?

07-08-2010, 10:14 PM
Yup,on a few chucks infact.

I use a Dremel chainsaw grinding stone,the bigger one 7/32 IIRC.

Gentley clamp the stone in the chuck,then clamp the stone's shank in the DP vise.Release the stone from the chuck.

Using the lowest speed start the DP up and gently close the chuck up until it just touches the jaws(index finger and thumb,just a quick,light bump).Stroke the quill up and down on the stone closing the chuck up more as the work progresses.

Last chuck I did was a 5/8" keyless that was running out .015 at 4".Less than 2 minutes running at 150rpm had it to within .0015,good enough for most folks.

07-08-2010, 10:23 PM
might have been in one of Guy Lataurds books the idea of revolving the chuck around a cylindrical abrasive stick....I haven't done it and would have think through a set up....I guess weird's is the same type of idea but you get the shank to hold onto

J Tiers
07-08-2010, 10:24 PM
hey, Darin... REALLY GOOD PLAN.....

I had figured on doing it outside the DP (lathe, etc), but your plan is pretty well guaranteed to do a good low runout even if the DP is out a bit.....


Thank you.

07-08-2010, 10:46 PM
Yup,it works good,so good I keep a "special" chuck at work with witness marks matching ones on the DP's spindle.I keep it hid away from the knuckle draggers.

So long as the pressure used to close the chuck is light and your careful for obvious reasons it works well.

J Tiers
07-08-2010, 11:50 PM
Already did the deed.... but since I had the chuck here, I did it on the lathe.

The runout after was constant at about 3 thou out to 3 inches, and about 2/3 of the "parallel runout" was gone also. (basically the same thing, the only part left was parallel runout)

By "parallel runout", I mean the amount that the jaw center is eccentric vs the spindle center, NOT counting wobble.

Jaws look quite nice, the ridges are gone, as is the bell-mouthing

Thanks again.