What Size Drill Bit for a 1/8 NPT Tap?
2021-8-17u2002·u2002Size Of The Drill Bit. Now that you know how to measure for a leak-free seal, you need to know the size of the drill bit required for a 1/8 NPT tap. As a general rule, the size of the drill bit required can be easily estimated by subtracting the pitch of the thread from its diameter. A 1/8 NPT tap requires an R-shaped drill bit.Get Price