Taps for hard materials

[John Stevenson]

When you are tapping, especially on hard materials, you start off taper, second then plug.

The difference in these being the amount of lead on the tap but once you are past the lead you are up to full OD no matter what number tap it is so all the work is being done by the lead.

Doing some stainless today and just thought that i have not seen the taps I use posted on here.

Don't know if they have a special name or not but I call them serial taps. Still taper, second and plug but as well as the difference in leads the OD is also reduced on the taper and second so it reduces cutting forces.

You have to use them in order as the taper or second will not finish a thread.




I have tipped these so you can see the flats on the crests of the threads showing the reduced OD.
I get these for a good tool company in China, not expensive but not cheap rubbish either.

[J Tiers]

The taper tap doesn't look as tapered as some of the GTD tapered ones I am familiar with. That set is for-sure the proper sequence, though.

The tapered tap also helps a lot in getting the tap started right when hand tapping. if you run it in well, you get enough good threads to start the next one, and so on.

is it the light? Or do those have the "pixie dust" nitride coating?

[Peter Neill]

Just as a point of interest, they are called 'Serial Taps'.
And yes, they took me by surprise a few years ago as I was just used to first; second; and plug.

Edit: Edited 'cos I didn't notice John already said they were Serial taps.

[JCHannum]

Just a FYI, the usual three piece tap set consists of taper, plug and bottoming taps.

The serial taps are not in common use here, but have their uses in hand tapping. They are not inexpensive though if you can find them.

[rkepler]

Just a FYI, the usual three piece tap set consists of taper, plug and bottoming taps.

The Brits use a different naming scheme that we do on the proper side of the Atlantic.

[John Stevenson]

The Brits use a different naming scheme that we do on the proper side of the Atlantic.

Proper side?
Is that going east to west or west to east ?
If we go east to west we get to New York
If we go west to east we get to California

So what's the proper side ?

[rkepler]

So what's the proper side ?

My side, of course.

Sheesh.

[38_Cal]

Interesting...had not run across that type of tapping "system" before. Makes perfect sense, though. Most of the taps I use are small, 6-48, 8-40, and gun specific sizes. Since many of the holes I need to tap are blind, I don't see where they would have an advantage for me over standard types.

David

[JCHannum]

David, with the standard US three tap system, you achieve the same effect without the need for running the taps in full depth.

A question and aggravation for me is why does the taper tap frequently have a point on the end with no thread cutting function at all? I grind these off, particularly when tapping blind holes as they often prevent getting any thread started at all.

[RobbieKnobbie]

Funny, I use them specifically for blind holes (though I generally skip the long taper tap). Nothing else will get that last thread.