This style of Threaded
Hole Centerline Location Gage is made similar to the Flexible
Threaded Hole Centerline Location Gage except that it is not slit. The
design intent here is that the Solid Threaded Hole Centerline Location Gage
is screwed hand-tight to the part surface that is perpendicular to the
thread. The pressure against the collar, as it is tightened, forces
the Solid Threaded Hole Centerline Locator to self center against the internal
thread flank angles. Yeah, it probably works, after all it is the
most popular style of threaded hole locator. There are many sizes
available from stock from at least two different manufacturers that
make these as a primary product.
The bottom side of the collar has been relieved so that only the
outer most diameter contacts the surface of the part. The problem
here arises if the surface is not perpendicular by design or in
error. Screwing against a sloped surface may tip the locator and
misposition the Threaded Hole Centerline Location Gage; which in turn will
give a very repeatable false reading.
A good thing is that it can be calibrated, but make sure the bottom
surface of the collar is checked for wear.