Help identifying a reamer

[Jim F]

DET #1 probably means "detail #1" .
We use that at work alot, different parts to use making tools, usually different parts for a die to make multiple parts from the same blanks.

 

[twooldvolvos]

If you drill a slightly smaller hole then ream it you could measure the hole with a snap gauge.

Stu

That's probably the most accurate way I've heard yet. Empirical is the way to go!