I am wondering about tapping a 1/4" NPT threads. The drawing from my customer shows the hole 18mm deep and tapped this depth. I see from the handbook the tapping size is 7/16". when i drill my hole then go to tap it, the tap won't go down this depth, maybe only 10mm. Should the hole be tapered ?
Also he has given me a dwg. of a 10mm thick plate with a hole drilled & tapped 1/8" NPT. I assume/guess i just tap from one side as far as the tap will go??
There must be some standard that these thread depths should be. any help appreciated.