Taps

[EdK]

I need to get some HSS taps and have had some questions about taps for awhile now so I thought I'd get them answered.

1. What makes a hand tap a "hand" tap versus any other type of tap?
   
2. What's the purpose of taps with the different numbers of flutes? I've seen taps with from 2 to 4 flutes.
   
3. Can a so called hand tap be used for power tapping?
   
4. Are coated taps worth the extra money?
   

Thanks,
Ed

[PixMan]

Hand taps have no chip control geometry, such as spiral point or spiral flute, which machine taps do have. As such, you have to reverse direction every 2 or 3 turns to break chips.

The number of flutes increases or decreases load "per tooth", though less flutes makes for a stronger tap. More flutes helps carry chips away better. I practical terms, you notice no real difference in how much pressure it takes to cut the thread.

NEVER use a hand tap for power tapping. You want to do a power tap cycle in one pass, and hand taps need that chip-breaking reversal every couple of turns.

Yes and no. If you have really abrasive material or have to do lots of holes, coatings help. There are TiN, TiCN, THL and more. The right coating can make all the difference in the world when you need to get it done. Rarely is this an issue in most home shop situations.

[Arbalest]

Don't know Ed, but there are also
5. Thread "forming" Taps that don't remove any material
6. Serial Taps:

http://www.arceurotrade.co.uk/Catalogue/...ic-BSW-BSF

No need to thank me Ed, glad to be of help ...

[Mayhem]

(10-03-2012, 06:25 AM)PixMan Wrote: ...NEVER use a hand tap for power tapping. You want to do a power tap cycle in one pass, and hand taps need that chip-breaking reversal every couple of turns...

That is a very valuable piece of info (in fact the whole lot was valuable). I often wondered about the chip breaking if a hand tap was to be used. Now I know not to try and to stop wondering!

[stevec]

I prefer spiral point or tip "gun" taps. They are intended to be used only for through hole tapping but I have been able to reverse them successfully and I drill the blind hole much deeper than I need to tap it in order to accomodate the string like chips that are forced ahead of the tap by it's design.

[Mayhem]

I never saw Arbalest's response until now, as we posted at the same time.

I have only recently heard about the thread forming taps, which produce an internal version of a rolled external thread.

Serial taps are a new one to me but a brilliant piece of marketing design, as you need to buy three taps to produce a thread. Someone had their thinking cap on there!!!

[stevec]

I can see where serial taps might be a help in the following "Excellent for tapping deep holes and tough metals such as stainless steel. ".
Especially for small (like 2mm) sizes but it sure sounds like an excellent marketing scheme as Mayhem mentioned and a "make work" plan for the user.

[EdK]

(10-03-2012, 06:30 AM)Arbalest Wrote: Don't know Ed, but there are also
5. Thread "forming" Taps that don't remove any material
6. Serial Taps:

No need to thank me Ed, glad to be of help ...

I already knew about thread forming taps but hadn't heard of serial taps.

Ed

[EdK]

(10-03-2012, 06:25 AM)PixMan Wrote: Hand taps have no chip control geometry, such as spiral point or spiral flute, which machine taps do have. As such, you have to reverse direction every 2 or 3 turns to break chips.

The number of flutes increases or decreases load "per tooth", though less flutes makes for a stronger tap. More flutes helps carry chips away better. I practical terms, you notice no real difference in how much pressure it takes to cut the thread.

NEVER use a hand tap for power tapping. You want to do a power tap cycle in one pass, and hand taps need that chip-breaking reversal every couple of turns.

Yes and no. If you have really abrasive material or have to do lots of holes, coatings help. There are TiN, TiCN, THL and more. The right coating can make all the difference in the world when you need to get it done. Rarely is this an issue in most home shop situations.

Enco has it all wrong then. Here's their description of a hand tap.

"Hand taps are popular in hand use, in general machine tapping, or CNC tapping. They are also appropriate for tapping the vast
majority of materials in through or blind hole conditions."

It doesn't surprise me though.

Ed

[stevec]

Sounds like an Enco pronouncement.