How to minimize runout centering in a 3 jaw chuck?

HMF

Site Founder
Administrator
Joined
Sep 22, 2010
Messages
7,223
While centering in a three-jaw scroll chuck, some runout is evident. Does anyone have any strategies for centering in a three jaw chuck?

Thanks,


Nelson
 
There is truth to be found in both viewpoints. If a 3 jaw is truly worn-out, then a simple jaw dress won't make it new again. Grinding is only part of the solution. On the other hand, if rebuilding a 3 jaw, then certainly, the jaws should be ground. This includes all the steps and all the faces.

I think that terminology is the problem here. Repair vs. rebuild. Both have their places.

For example, on one of my machines, I have a fairly new, good overall condition 10" 3 jaw. In paranoia, someone over-tightened it on a piece chucked in just the last 3/4" or so of the jaws. That of course, "sprung" the chuck. Now, if the top jaws are removed, the master jaws chuck pretty true, but if the tops are on, there is runout and a very light grip (if any) away from the face. Seems like this is consistent throughout the chucking range. My thinking is that this chuck would benefit from a light dressing on the jaws. I've not done it yet, but plan to.

On the other hand, another machine has a well worn 12" 3 jaw. Lots of slot everywhere. I plan on a teardown to see what needs to be done to make it serviceable. Very likely more than a simple grind of the jaws.
 
Back
Top