aczlan
Good Morning!
Neat, threading conduit at work (Rigid die set and power head) I was taught to run the tap in until there are 1-2 threads past the end of the die for a regular end and 1-2 threads past the end of the fixture that the die mounts into for a box thread (to go into a box).There's a specific number of turns an NPT tap is supposed to go in for a given thread size. You should be able to Google up a chart. I'd be surprised (disappointed really) if the cheapskates overseas aren't short tapping shit to save on tooling.
Aaron Z