3/8 NPT threading

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Unka' George [George McDuffee]

------------------------------ Watch out w'en you'er gittin all you want. Fattenin' hogs ain't in luck.

Joel Chandler Harris (1848-1908), U.S. journalist. Uncle Remus: His Songs and His Sayings, "Plantation Proverbs" (1880).

"Proctologically Violated©®" wrote in message news:rtCKh.331$ snipped-for-privacy@newsfe12.lga...

Did you check at Home Depot? :-)

A rule of thumb machinists use (I are one) is five threads from the top of the tap. It may not yield a perfect depth, but will keep you out of trouble. It is always functional.

Harold

Which end of the tap is the "top"? Did you mean "tip"?

Joe Gwinn

Correct. Starting with the last full thread, count down to the surface. Five full threads still exposed should pretty much guarantee a functional fit.

Harold

Why do they have all the extra threads for?

Wes

you have to run the tap all the way into the block your tapping. why not get a pipe nipple and try it in your tapped hole?

"Proctologically Violated©®" wrote in message news:rtCKh.331$ snipped-for-privacy@newsfe12.lga...

"Dick Cheney's Left foot" wrote in message news:XV_Kh.2080$ snipped-for-privacy@newsfe12.lga...

Absolutely wrong! That would yield a well oversized thread. Aren't you paying attention? (Trolls usually don't).

Tapping that deep might be functional with a nipple, but try that with automotive angled brass fittings and see how you'd run out of the ability to tighten the thread, and it would still be lose.

.why not get

Which would readily show you that you had already tapped too deeply if you drove the tap to full depth.

Harold

The OP was refering to standard plumbing fittings. wake up harry

I've tapped quite a few NPT in my day. I find that I typically need to run the tap quite deeply in order to get a pipe nipple to seat 75% its full depth. Nothing wrong with using a pipe nipple as a cheap thread gauge, run the tap in and test, run in some more......etc.

Tony

Quiet, Tony. I'm sleeping. :-)

Harold