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TMX Scroll Chuck Variation

bp_newb

Plastic
Joined
Jun 28, 2018
Wondering if anyone has had this issue before... I've got a 6" TMX, 6 Jaw, Scroll Chuck. I have it fixtured into a set-tru type back plate that allows me to dial in work pieces. The issue I've discovered is if I dial in a drill rod, remove it, and then reinstall it, it only returns to zero if I use the same bolt to operate scroll.

So for example if I indicate when using bolt 1 to tighten.

BOLT 1: TIR 0
BOLT 2: TIR 0.004"
BOLT 3: TIR 0.007"

If I use Bolt 2 to tighten when dialing:
BOLT 1: TIR 0.007"
BOLT 2: TIR 0.000"
BOLT 3: TIR 0.004"

My guess is this is some sort of backlash issue? It's very repeatable. Has anyone dealt with this before? I know simple answer is always use same bolt for tightening.
 
Thanks.

It's barely a year old and I don't use it that much. Just started noticing it. So assume it's gotten worse recently for some reason.
 
Most of the chucks I use have only one key socket, so there is no such issue.

But I think I have seen chucks with three key sockets where one was marked with "0." I suspect the 0 socket was the one that was tightened when the jaws were finish ground. It does not matter which socket is used to remove the work, of course.

I have seen chucks with enough wear that the jaw gripping surfaces are not parallel when tight. That condition allows the work to wobble at random after tightening, so removing and installing work will result in random indicator readings.

Larry
 
Larry,
Thanks for input. Pretty sure this isn't a jaw wear issue. Since chuck is so new, and I haven't clamped anything tapered in it. I can grab a work piece that's sticking 8" out of chuck and apply pressure and nothing shifts. Also, results are very repeatable tightening the different sockets.

Luke
 
The scroll is fitted too loosely in the chuck body. Tightening each of the three sockets pushes the scroll off center in a different direction. You will always have to use the same socket that was used prior to truing.
 








 
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