Terry wrote:

I may take another pass on the shoulder because it is a very tight fit.
I did undercut the shoulder. The backing plate is larger than the
chuck, so I can not indicate the back of the chuck. But I can indicate
the front of the chuck, and I did this very carefully by closing the
jaws all the way, and lifting the indicator point over each of the
three gaps. This showed it was about +.003" on one side of the chuck
indicating that it was not square to the backing plate which measured
.0002" on the part extending past the chuck.

I will pull of the backing plate, counterbore the bolt holes and take
another .0005" from the shoulder and try it again.

Thanks


Suggest you find out if the front of the chuck body is parallel to the back.
This would be easy if you had a surface plate and surface gage onto which you
could catch a dial test indicator, but there are many ways to do it.

Easy does it taking off that .0005"! I've been known to use a (shudder) file
under such circumstances ..

GWE