I filled out the less common sizes in my tap and die collection from
the bin in a second-hand store, without regard to the OD of the dies,
since I'd probably only turn them by hand to repair existing threads.
Recently I got out the 1/4-18 NPT die to clean up rusty threads and
noticed that it was missing the adjusting screw that holds the die
open against the pressure of the diestock clamp screws.

The die is 1.5" round and the adjusting screw enters radially into the
slot, not perpendicular to the slot on a chord like normal split dies.
I made a 32TPI screw which fit when turned to 0.295" OD, not much more
than 0.281" or 9/32" which is a standardized thread:
https://www.amazon.com/Special-Threa.../dp/B0141JFGRM
The die manufacturer is Card, USA.

The female adjusting screw thread in the die is noticeably tapered.
Since this is a pipe thread die the exact cutting size doesn't matter
and the die OD is under 1.500" with the home made screw fully
inserted, but I have other similar dies for straight threads and
adjusting then to cut the right size without a gauge would be tedious
if my custom setscrew is out of spec..

Does anyone have this type of die to measure or know whether or not
9/32-32 is the proper thread size for this adjusting screw?

Thanks
-jsw