Taps & Dies

Signed-In Members Don't See This Ad

beck3906

Member
Joined
Aug 13, 2005
Messages
2,139
Location
Belton, TX 76513
Is there anything way to determine the double and triple leads if not obviously stamped on the tap or die? Is there a way to determine whether the tap is a Norma, bottoming, or starting?
 
Signed-In Members Don't See This Ad

Monty

Group Buy Coordinator
Joined
Mar 4, 2005
Messages
8,363
Location
Pearland, Texas, USA.
From the McMaster-Carr web site:
starter.png starter tap
through.png through or normal tap
bottoming.png bottoming tap

Not sure about how to distinguish a double or triple start.
 

skiprat

Passed Away Mar 22, 2022
In Memoriam
Joined
Oct 19, 2006
Messages
7,812
Location
In a Skip in Wales
Any decent brand of tap will have the spec etched on it. Something like M10 x 0.5 x 3 etc

If you have a normal one to compare, you will see the helix angle is far more on the multi start.

I'll take a pic or two of various ones if you would like. Just gonna eat first and take my daughter back to uni.......
 

magpens

Member
Joined
Feb 2, 2011
Messages
15,911
Location
Canada
Send them all to me and let me figure them out !!!!! :biggrin::wink:

You could do a trial in a piece of scrap to determine whether it's triple, double, or single ... examine the threads and count the starts.

There is some useful info on the web about distinguishing the tap types ... I'll see if I can find it again.

Here it is:

http://www.newmantools.com/taps/taptech.htm

[FONT=HELVETICA, VERDANA, ARIAL][SIZE=-1]The kind of hole to be tapped has much to do with the style of tap that's best suited. Some holes go all the way through. Others, while not throughholes, still are relatively deep. Some are quite shallow, little deeper than diameter. Each of these three kinds of holes through, deep-bottoming blind, and shallow bottoming, has a tap or group of taps best suited to requirements.

Taper Taps have 7 to 10 thread chamfers to distribute cutting action over many teeth and the taper also acts as a guide in starting.

Plug Taps, with a chamfer over four threads, is most widely used in through holes and where there is sufficient room at the bottom in blind holes.

Bottoming Taps are made with just enough chamfer for starting in the hole, only 1 to 2 half threads. As the name implies, it is designed to thread blind holes to the bottom.


And also Wikipedia:

[/SIZE][/FONT]
Bottoming tap or plug tap. The tap illustrated in the top of the image has a continuous cutting edge with almost no taper — between 1 and 1.5 threads of taper is typical. This feature enables a bottoming tap to cut threads to the bottom of a blind hole.
Tap and die - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Tap_and_die
 
Last edited:

Rockytime

Member
Joined
Jun 3, 2014
Messages
1,074
Location
Arvada, CO 80003
Hi Skiprat, You make excellent tutorials. I have a question. All my lathes are imperial or inch. The only thing I own that are metric are my electronic calipers. Since 1mm is equivalent to 0.03937 if I were to get metric taps and dies for pens is 0.04 close enough? I think it would work but not sure. I have never cut threads that small.
 
Top Bottom