The Committed-Catch Gate

Three physical conditions decide the tool before any feature does, and each can rule out a whole family on its own. Answer them in order.

Gate 1 — bore

Run an impression block first if you are guessing.

Gate 2 — annular clearance

An overshot has to physically go around the pipe inside the hole.

Gate 3 — commitment

A conventional die collar cuts thread and stays. That is a commercial decision as much as a technical one.

Answer all three gates to see the routing.

This routes on physical availability only. Fish-top condition, string design and the economic fishing window still apply — and the pipe has to be stationary for any thread-cutting tool to work at all.