I was aware of the nature of the chuck jaw mounting from Richards description. However there remained the real state of the term "running out" and he has now clearly identified that there is no run out when in operation. Which leads me to one last question for Richard if I may………….when you measured the "run out" of 0.3mm on one jaw, was that with the jaws clamping on a piece of stock, or were the jaws unclamped?

Edited By David George 1 on 04/10/2019 23:15:29

A good quality three jaw chuck should have no more than about 0.05mm runout. 0.3mm is way way way too much, even on a cheap chuck or a worn out old chuck. Anything over 0.1mm would be classified as defective in most contexts.

"Welding wire to pack the gap"????????????

That sounds like a big gap to have between a jaw and the slot in the chuck. I am imagining 1.5mm (1/16" ) welding wire. If so, I think that you have a heavy doorstop, and are in the market for a new chuck.

Unless you fancy some interesting remedial work on the chuck body! (Make up a new "Slot" to be fitted into the chuck body to restore the jaw/chuck fit to where it should be. )

If so, maybe you should take up an offer of physical help from some one within reasonable driving distance.

THEN you can start dealing with any jaw misalignment.

Howard

0.3 mm is still too big a gap, between Jaw and chuck in my book.

And the source of the jaw run out has not been found. Not that a sloppy fitting jaw will help matters.

My suggestion is still to investigate for damage / swarf / errors in a logical sequence before removing metal.

Without checking everything to find the error, it can never be corrected..

A scattergun approach may find the error, if you are lucky; but a logical sequence of checks is likely to find it sooner., more certainly.

Howard

Michael,

I can find no reference to squashing welding wire to 0.3mm, in Richard's 04-10-2019 22:30:57 post.

The post says "I have enlarged the tenon slot in the jaw slightly, which has improved run out….now the one tenon slot is bigger and causes movement when tightened, which i have alleviated by using some welding wire to pack the gap"

Now I am wondering how the metal removed from the jaw can be replaced to make the jaw a good fit in the chuck body, again, so that finding the cause of the 0.3mm run out can be investigated, and, hopefully corrected.

Richard,

You need to find someone relatively near to you, who has the knowledge, and facilities to get things back on track, and then start investigating the source of the problem.

Hopefully, you will get the chuck back together, with the knowledge of where the problem is. Then action can be taken to cure it, possibly grinding the jaws so that are in alignment.

Howard

Fat fingers again, and again and again

Edited By Howard Lewis on 05/10/2019 18:24:11

Edited By Howard Lewis on 05/10/2019 18:25:09

I took the mention of squashed welding wire in the original post to be an attempt to cure the 0.3mm run out. The mention of increasing the clearance of the jaw in the slot came later.

Lets just hope that he gets it sorted ot rather than having a scrap chuck!

Howard