Tapping NPT pipe threads (2024)

I need to tap some pipe threads, but because of the taper, I'm not sure how deep to go with the tap.
You Tube can often be a quick reference.
I found this one - what y'all think ?
Quite remarkable to me !

If you drill the correct drill size thru, then maybe start with 10 complete turns of the tap handle to start. The use a quality fitting, or the fitting your going to use, and from start to hand tight should be 3 turns.

likely you'll need to go another 1/2-1 turn to get the right depth.

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As to the video, that's one way of doing it. Certainly how my fabricator buddy next door would do it

For any pipe thread I do on a Bridgeport I have the tap about 1/8" under the top of the tap wrench, and use a bar whose diameter is approx .002 under the width of the flats of the tap. Put that in a chuck/collet and use it to guide the tap to keep it straight

Oh my. What a video.

Without the benefit of a thread gauge, leave the last six to seven threads on the tap showing and you should be fine.

I've always left 8 threads on non-gaged stuff. Leaves a little room for a touch-up later if it's ever needed.

Edit: just watched the video. Oh my.

eKretz said:

I've always left 8 threads on non-gaged stuff. Leaves a little room for a touch-up later if it's ever needed.

Edit: just watched the video. Oh my.

Click to expand...

That should be titled "How Not To Cut a NPT Pipe Thread!!!"

Overland said:

I need to tap some pipe threads, but because of the taper, I'm not sure how deep to go with the tap.
You Tube can often be a quick reference.
I found this one - what y'all think ?
Quite remarkable to me !

how to tap 1/4 npt thread - Google Search

Click to expand...

LOL!

And that's the first result chosen by google - I wonder how many defective parts they will take responsibility for!

NPT gauges are cheap, just buy one.

Edit: I missed the video, I was referring to the text result atop, I will refrain from copy pasting it here lest it be taken as endorsem*nt...

guythatbrews said:

Oh my. What a video.

Without the benefit of a thread gauge, leave the last six to seven threads on the tap showing and you should be fine.

Click to expand...

I don't know how common it is, but I have NPT taps from two different premium manufacturers (Reime Noris and UFS) that have the gauge length ground in as a specified distance from the end of the tap, read it from the datasheet, tap to that depth, go. They gauge perfect with a two step gauge every time.

dkmc said:

I watched the video. I've run across some of his plumbing work.
Only thing missing was a view of his plumbers crack.

Click to expand...

Crack kills.

Overland said:

I need to tap some pipe threads, but because of the taper, I'm not sure how deep to go with the tap.
You Tube can often be a quick reference.
I found this one - what y'all think ?
Quite remarkable to me !

how to tap 1/4 npt thread - Google Search

Click to expand...

Well, you should have it under control now!

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Think Snow Eh!
Ox

It would be less stressfull watching a man beat a sack full of kittens
than watching that drilling and tapping video. Seriously.
And the perfect thing is, that guy in his mind, probably thinks he is
going an excellent job. So excellent, he decided to make a video to
share his excellence with the world. I also love his drill matches his shirt.
The quintessential essence of perfect.

-Doozer

Doozer said:

I also love his drill matches his shirt.

Click to expand...

There's a rumour it matches the tattoo on his ass, but maybe we don't want to find out.

You been hangin' at the Y?

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Think Snow Eh!
Ox

Doozer said:

And the perfect thing is, that guy in his mind, probably thinks he is
going an excellent job. So excellent, he decided to make a video to
share his excellence with the world.
-Doozer

Click to expand...

And the pathetic thing is, a high percentage of the viewers actually 'learned' how to tap pipe threads. And think that is the proper way to do the job.

dkmc said:

And the pathetic thing is, a high percentage of the viewers actually 'learned' how to tap pipe threads. And think that is the proper way to do the job.

Click to expand...

This is my whole beef with you tube "learning". Although hopefully most folks will realize this guy is not the right teacher for anyone, some won't.

There is no vetting of content. Could be ill advised, an absolute lie, or downright dangerous. But it is popular because it is passive. You don't even need to be literate. Grab a beer, sit back, and be learnt. But the more I get teached seems the less I know. At least I drank some beer so it's a good day.

I'm not knocking the beer drinking part. It's the best part!

Not to say there isn't some great informative stuff on you tube. But if you don't know what you don't know it's hard to suss out the good from the bad. And therein lies the rub.

I won't deny you tube is great for figuring out how to take your washing machine apart. Or finding where those sneaky automotive engineers hid your crank position sensor.