Tap Drill Size for NPT & NPTF Taper Threads
Tap Drill Size for NPT and NPTF Taper Threads

You got the job. You ordered and received material. You ordered and received taps and gages from North American Tool. The job is now out in the shop to be manufactured and the first operation is to produce a hole before tapping. How do you determine what tooling to do that with?
Holes before tapping pipe threads are produced either straight or tapered. The choice of method is