What is the right tap size to use for a 1/2" NPT hole? 3/4" seems to be right but I've got a 3/4"-16 whch is too fine and a 3/4"-10 which is too course. It looks like a 3/4"-12 would be right. Or do they just sell a 1/2" NPT tap? I guess they do as I have both a 1/8" NPT and 1/4" NPT tap.

So...as I've written this it s probably a stupid post...and I probably just need to call someone...but as I need to go to lunch, maybe I'll get a quick answer while I'm gone.

Mark M.

Mark,

There are special taps for NPT. NPT is tapered and requires a special tap. Try taking the both parts male and female to Home Depot in the plumbing department. They might just do it for free. Otherwise they can sell you the tap.

1/2 NTP is a taperd thread, 14 threads per inch, drill size for hole is 45/64 (.703 dia).
AL