Who made the chuck? If it came with the Grizzley, it is likely
not US made -- just as the Grizzley is not US made.

The chuck is to replace the original chuck. I asked the manufacturer if
it was US made, he said it was. I am not divulging the maker at this point.

Almost certainly a metric spindle thread. Do you have a set of
metric thread pitch gauges? The diameter (1-3/4) works out as about
44.45mm, and the thread pitch as 3.18mm (likely 3.2mm).

Uh, I hope that a pitch gauge refers to a number of leaves with the
thread teeth stamped out. I only have Imperial. If an 8tpi drops in
pretty damn close, what will using a metric pitch gauge do?

I think finding an M45x3 nut will be the cheapest way to determine the
actual thread... Comments?

Hmm ... the downloadable spec sheet does *say* 1-3/4 x 8, but
I'm not sure that I trust it.

http://www.ibmmuseum.com/OhlandL/lathe/G9972Z_fm.pdf

This is the original owner's manual. If you look, there are two listed
spindle threads right next to each other, M45x3 and 1 3/4 x 8.


It does say "Country of origin: China", and they list the
following chucks:

5" 3-Jaw Chuck with Two Sets of Jaws
6-1/2" 4-Jaw Chuck with Reversible Jaws

Are these the ones in question, or did you get a chuck from another
source?

A 5" from another source.


O.K. The manual also says 1-3/4x8 spindle. So, perhaps the
problem is in the chuck backplate.

Is it normal for the bolt hole centers in the chuck to start at 4.451 on
top, expand to 4.487 on the chuck bottom, then back to 4.470 on the
adapter plate? Sort of makes me wonder how well the adjustment feature
will work when the mounting bolts are already against the outside of the
counterbore...