On Mon, 24 Oct 2005 16:13:26 -0700, larry g wrote:

I'm thinking that this is a production gauging tool. I can see it for
checking head height on something like a rivet, bolt, or other similarly
shaped item. Drop the unit under test into a hole and slide it under the
micrometer head and measure the head height from the disc with the holes in
it. I'm guessing that the disc with the holes in it is ground and the two
faces are parallel.
lg

The disk is ground. I put it on my surface plate and measured, the faces
of the disk are parallel. The micrometer head is an old Brown & Sharpe.

It came in an old box of machinist's clamps and calipers that I bought
at an auction. Hate to just pitch it, maybe I'll stick it on Ebay if
no one wants out of this group. If you do want it, make an offer.