Form Tapping NPT

BoscoDrummer · Mar 7, 2018

I have some Threads to cut into 110 copper, i have heard thread forming taps are preferred in this material. That being said the type of threads are pipe. Is form tapping NPT threads even a thing? I'm not planning on doing it but just wondering.

Mtndew · Mar 7, 2018

Yes you can buy NPT form taps.
Thread milling would be a better option IMO because form tapping mushrooms the C110 copper.

litlerob1 · Mar 7, 2018

Threadmilling would be preferable, but if you need to use a Tap, I would use an Interrupting Tap; In the picture; Regular on the Left and Interrupted on the Right.

BoscoDrummer · Mar 7, 2018

Litlerob1 I am not familiar with interrupted taps. It looks like the start of the tap is regular for lead start then begins its interrupted pattern. Seems like it cuts every other tooth. Is the benefit lower cutting preassure?

litlerob1 · Mar 7, 2018

BoscoDrummer said:
Litlerob1 I am not familiar with interrupted taps. It looks like the start of the tap is regular for lead start then begins its interrupted pattern. Seems like it cuts every other tooth. Is the benefit lower cutting preassure?

No, I would guess it has a similar pressure, but it breaks the chip. Notice MtnDew's post doesn't say form Tapping will create the Mushroom effect, it just says "Tapping". While a Form tap IS going to take much more pressure and the technology is in fact displacement, ANY Tap is going to create that Mushroom effect. C110 is soft, so I like to break the chip.

R

Mtndew · Mar 8, 2018

litlerob1 said:
Notice MtnDew's post doesn't say form Tapping will create the Mushroom effect, it just says "Tapping".

Check again, maybe your glasses had a smudge on them

litlerob1 · Mar 8, 2018

Mtndew said:
Check again, maybe your glasses had a smudge on them

I don't wear Glasses, I wear freakin' Goggles. But I did miss it. I still say the same thing as in #5 any tap will cause pooching in Copper, never tried forming an NPT but can only assume it would be worse. NPT tapping is displacing.

R

Leg17 · Mar 8, 2018

That 110 soft copper is real 'grabby' when trying to tap a straight hole.
(Or drilling or reaming, for that matter.)
I expect a tapered tap to be even 'more grabbier'.
Thread forming seems like it could be the 'grabbiest', but I have never tried it.

litlerob1 · Mar 8, 2018

Leg17 said:
That 110 soft copper is real 'grabby' when trying to tap a straight hole.
(Or drilling or reaming, for that matter.)
I expect a tapered tap to be even 'more grabbier'.
Thread forming seems like it could be the 'grabbiest', but I have never tried it.

They must've covered that technical data in the second part of the class. "Grabby" :stirthepot:

Leg17 · Mar 8, 2018

litlerob1 said:
They must've covered that technical data in the second part of the class. "Grabby"

Nah, you had to stay after for extra credit to get the proper lingo.
But, now you have it for free!!

metalmagpie · Mar 9, 2018

Leg17 said:
That 110 soft copper is real 'grabby' when trying to tap a straight hole.
(Or drilling or reaming, for that matter.)
I expect a tapered tap to be even 'more grabbier'.
Thread forming seems like it could be the 'grabbiest', but I have never tried it.

Try lubricating with a can of evaporated milk, no kidding.

metalmagpie

Leg17 · Mar 9, 2018

Velly Intalesting.
And maybe not shtoopid.
(It's a generational thing for those that remember 'Laugh In'.)

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