On Sat, 10 Sep 2011 10:51:36 -0700, Jim Stewart
wrote:

Wes wrote:
Anyone have good pointers to where I can get a 6" scroll chuck with an adjustable back
plate? I know Buck makes one, I'm not sure what chuck we have on the LeBlond at work but
it is sweet being able to dial in concentricity. I'm trying to find the best deal on a
good chuck.

I need to get this accessory purchased soon. I just heard that the AG for Michigan may be
lifting the disability to own suppressors in my state soon which would divert my metal
working budget to my gun budget.

Don't mean to be a smart-ass, but could someone
tell me the advantage of a 3-jaw chuck that you
can dial in verses a 4-jaw independent chuck.

It seldom takes longer than 2-3 minutes for me
to dial in a 4-jaw chuck to .001". I have a
dial indicator and base all set up and seldom
use a 3- jaw chuck any more. Am I missing
something?
Greetings Jim,
I do a lot of work that has to run true better than .0005". When I
dial in a part in the 3 jaw adjustables it repeats better than .0005"
at that diameter and chucking pressure. When I change diameters and
need to re-adjust the chuck it almost never takes me more than 2
minutes. HOWEVER, if I had only one chuck it would be a 4 jaw. Lots of
the time I bore jaws, and three jaw chucks with top jaws make that
real easy. None of my 4 jaw chucks have top jaws, but I'm sure they
can be had. BTW, I bought several years ago a 4 inch chuck on a 5C
arbor. It is Chinese made. I was unable to find one that wasn't. I
took it apart and made it adjustable. The jaws were all in the same
plane and perpendicular to that plane but the back face of the chuck
was not perpendicular to the jaws. I tightened the jaws onto a just
turned spud and machined the back of the chuck true. Then I modified
the chuck to be adjustable, with only 3 equally spaced screws instead
of 4. It repeats better than .0008". And adjusts fast, but not as fast
as 4 screws.
Cheers,
Eric