I want to learn how to read these things. For example, what size hole and what type of screw does a 3/8-16-NC tap require? What does the NC and the -16 mean? 3/8 = requires a 3/8 inch hole?
Reading a tap & die set
- Thread starter Jmmsbnd007
- Start date
if the chart isnt included with your die set youre fuxor3d 
you dont make the hole you want to tap the same size as the tap/die, or itll just go right into the hole wont it?
so, the pilot hole has to be slightly smaller than the desired finished hole.
yes, the -16 is threads per inch (which would be a coarse thread, fine would be something like 24 or 32 for very fine)
been a while since i used one, and even then it wasnt terribly often. id guess the piece labeled 3/8 -16-nc is for something like a 5/16 bit? maybe a 9/32? go by a hardware store and they could probably help you, or hell, call one for gods sake
you dont make the hole you want to tap the same size as the tap/die, or itll just go right into the hole wont it?
so, the pilot hole has to be slightly smaller than the desired finished hole.
yes, the -16 is threads per inch (which would be a coarse thread, fine would be something like 24 or 32 for very fine)
been a while since i used one, and even then it wasnt terribly often. id guess the piece labeled 3/8 -16-nc is for something like a 5/16 bit? maybe a 9/32? go by a hardware store and they could probably help you, or hell, call one for gods sake
eplebnista
Lifer
- Dec 3, 2001
- 24,123
- 36
- 91
Taps have the drill size stamped on them too.
*stalks of grumbling about someone stealing his $300 Tap and Die set*
*stalks of grumbling about someone stealing his $300 Tap and Die set*
It's for a 5/16... I don't need help, just wondering how you read and interpret all the labels.Originally posted by: xSauronx
if the chart isnt included with your die set youre fuxor3d
you dont make the hole you want to tap the same size as the tap/die, or itll just go right into the hole wont it?
so, the pilot hole has to be slightly smaller than the desired finished hole.
yes, the -16 is threads per inch (which would be a coarse thread, fine would be something like 24 or 32 for very fine)
been a while since i used one, and even then it wasnt terribly often. id guess the piece labeled 3/8 -16-nc is for something like a 5/16 bit? maybe a 9/32? go by a hardware store and they could probably help you, or hell, call one for gods sake
"3/8 = requires a 3/8 inch hole?"
You DO need help, and eplebnista gave it to you, with no thanks I noticed.
You DO need help, and eplebnista gave it to you, with no thanks I noticed.
Well, how would I know if the 3/8 meant something else? It says 3/8, what else am I to assume? I want to know what the markings mean, I'm not looking for charts.
Ok to read the tap chart, remember that the size of the tap is gonna be bigger than the hole that has to be drilled. As you tap the hole, you are physically cutting the threads and making the hole bigger (to the size listed on the tap IE. 3/8".) A 3/8"x16 tap uses a 5/16" drill bit likewise a 7/16"x14 tap willl use a #U drill bit.
3/8ths would be the diameter of the thread, not the hole.
3/8 - 16 would be a 3/8ths thread diameter with 16 threads per inch.
NC = National Course
NF = National Fine
Both the above terms relate to the shape of the thread as well as how many threads per inch.
I finer thread requires a different tip shape (Crown) than a course thread, thus you have the two different standards.
Metric threads are another story, you have course, medium and fine but with one tip shape standard.
I am not even going to bother to try to explain pipe threads until you understand these basic terms first.
Thanks for the basic help... what's with naming drill bits with letters, anyway? Thanks to the guy above for explaining the whole it-turns-into-a-3/8-hole type thing.
I don't even understand pipe thread and I am a mechaic too. All I know is my air tools use a 1/4" fitting.
Number and letter bits have to do with machining and machine shop processes.
And your welcome.
Pipe threads are threaded with a tapered die or tapered tap, along with diameter and thread pitch, there is also taper per inch as well.
I have cut thread on pip for air lines in a shop I worked in, I just never understood how they named the sizes. a 1/4" pipe thread is actually for a fitting that has what looks like a 1/2" dia. Yes pipe thread tapers and has to be sealed with pipe dope or thread tape.
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