Taps and dies

[Rob]

Hi folks

Apologies for this starting way off topic but I've been reading with interest the posts on cutting threads.  This is something I've never done but have the occasional need to.

Many of you clearly have lots of experience....any pointers please at the right tools (quality wise) to purchase and some simple starter information would be gratefully received.

Many thanks

[Ken S]

Rob,

I have found this series interesting:

http://www.youtube.com/watch?v=q7UvwyLSdsM

Just in case the link doesn't work, do a Google on "tubal cain taps".  I think the demonstrator, Tubal Cain, is a retired metal shop teacher.  He has done a series of you tubes. 

Ken

[Rob]

Thanks Ken

Ill check that out tomorrow. Off to celebrate my 50th today :-)

[Ken S]

Happy Birthday, and many more happy birthdays, Rob.

Ken

[Herman Trivilino]

Just in case the link doesn't work, do a Google on "tubal cain taps".  I think the demonstrator, Tubal Cain, is a retired metal shop teacher. 

Wow, Ken, that's a very interesting lesson.  What an impressive tool collection!  Who's gonna inherit that?

I'll have to check out more of his videos.

Rob, I just have a very small and inexpensive tap and die kit.  I'm not very experienced with them either.  I wonder what happened to my father's collection of tap and dies?  Which brother got those?

[Herman Trivilino]

Off to celebrate my 50th today :-)

Happy birthday, Rob.  50's a big one.  Get yourself something special like an ear ring.  It'll make you feel young again (after it stops hurting).

[Jeff Farris]

Herman, you're full of surprises!

[Elden]

Rob, happy birthday!
Maybe Herman meant for Rob to get for himself so he could have in stock so as to get himself out of the dog house later on!

[Herman Trivilino]

No Elden, that requires a matching pair.   

[Elden]

Rob watch all of Tubalcain's you tubes on taps and dies. I believe there 3 on taps and 3 on dies. He also has very informative ones on drill bits.

[Ken S]

I found this online and thought it might be of interest:


STANDARD & METRIC THREAD SIZES

STANDARD thread size refers to a thread measurement system commonly used in the United States called the 'Unified Thread Standard'. This system uses two numbers to identify thread size, for example: 1/4-20 or 2-56.

The first number references to the major diameter of the screw (major diameter is the outside diameter of the screw measuring on the outside of the threads, minor diameter is the smaller shank diameter, measuring between the threads). Larger screw sizes typically use a fraction in inches to identify major diameter, so a 1/4-20 screw has a major diameter of 1/4". Smaller screw sizes will use a 'gauge' number such as 0, 1, 2, 3, 4, 6, 8, 10, etc., to identify major diameter.

The following formulas can be used to translate the gauge number into decimal inches or metric (or use cross refernece chart below).
Where 'n' equals gauge number:
n x 0.013 + 0.06 = major diameter in decimal inches
n x 0.3302 + 1.524 = major diameter in millimeters

The second number (80, 72, 64, 56, 32, 20, etc.) specifies the number of threads over a distance of 1" (25.4mm).

So using the above information, a standard thread size of 2-56 has a major diameter of:
0.086" (2 x 0.013 + 0.060)
2.184mm (2 x 0.3302 + 1.524)
with 56 threads per 1" (25.4mm).

Following is a cross reference showing: number gauge / decimal / metric:
       
0   0.060"   1.524mm
1
0.073"
1.854mm
2
0.086"
2.180mm
3
0.099"
2.515mm
4
0.112"
2.845mm
5
0.125"
3.175mm
6
0.138"
3.505mm
8
0.164"
4.166mm
METRIC thread sizes also use two numbers to identify thread size, for example: M3.5 x 0.60. The first number describes the major diameter in millimeters (to find decimal equivalent, divide millimeters by 25.4, 3.5 ÷ 25.4 = 0.137"). The second number designates the pitch of the thread, which is basically the distance from any one point on a thread to a corresponding point on the next thread. Following is a cross reference chart showing how pitch relates to threads per inch (25.4mm):
   0.30mm   84 3/4       0.60mm   42 1/4
   0.35mm   72 1/2       0.70mm   36 1/4
   0.40mm   63 1/2       0.75mm   33 3/4
   0.45mm   56 1/2       0.80mm   31 3/4
   0.50mm   50 3/4           

[Herman Trivilino]

The following formulas can be used to translate the gauge number into decimal inches or metric (or use cross refernece chart below).
Where 'n' equals gauge number:
n x 0.013 + 0.06 = major diameter in decimal inches
n x 0.3302 + 1.524 = major diameter in millimeters

So the diameter increases with increasing gauge number.  The opposite of wire gauge numbers!

The second number designates the pitch of the thread, which is basically the distance from any one point on a thread to a corresponding point on the next thread.

That distance being measured in millimeters, correct? So in standard measure it's the number of threads per inch, and in metric it's the millimeters per thread.  Interesting.  And confusing, too.   

Now I think I'm closer to understanding those numbers printed on my taps.