Working with Tap & Dies

[ARRX7]

Hello! I'm new to the forum and new to fabricating stuff on my own. I figured it's time for me to step up (and save money).

I just purchase a, gulp, harbor freight tap and die set (standard) to place a threaded hole in a block off plate on my intake manifold.

The tap is 24 threads per while the brass nipple I was planning on using (boost nipple) is 27 per, so I'm thinking, this ain't gonna work.

My question is can I expect to find brass fittings with 24 threads per or have I purchased a tap and die kit that just doesn't work with most bolts, nipples, or anything else I may come across in a typical hardware store? TIA

~M

[brn agn]

Your brass nipple likely has NPT threads, which means that the threads are tapered vs. straight like a bolt. The tapered threads provide a more efficient seal. My recommendation is to purchase a tap that will work with your part.

If you decide to go this route, do not run an NPT tap all of the way through the part you are threading. If you do, the minor diameter of the threads will be too large and you nipple will either be very loose, or will not seal.

Below is a link to an NPT pipe tap. HTH.

http://www.grainger.com/Grainger/items/4GT61

[ARRX7]

Perfect! Unfortunately, the Graingers in my area are closed. At least I now know what to get. Thanks for your help. Incidentally, if I wrap the fitting with Teflon tape, shouldn't that help with sealing?

[CarlC]

Teflon tape or paste is a good addition.

If memory serves, for a 1/2" NPT 7 threads of the tap should still be exposed at final depth. It's is always easier to tap a little deeper than to go to far on a tapered tap.

[brn agn]

The link to the Grainger website is the first one I thought about. You should be able to get the same tap from places like Ace Hardware, Lowe's Home Improvement, etc...



Good luck!