M14×0.8 triple start thread die
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. Got my triple start thread taps and die in the mail 
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hooked
Member
I am just a beginner, but I have been learning with an M14. I am finding that .545 - .550 seems to be ideal for me. So I have been targeting .545 and getting great fits. I am using a different pitch, though.
Rick Herrell gave me a great tip recently in another thread:
"Use the 10% rule when making tenons for threading with a die."
"Reduce the nominal tenon size by 10% of the thread pitch."
nominal tenon size: 14mm = .551
pitch: .8mm = .0135
10% = .00135
.551 - .00135 = .549
Rick Herrell gave me a great tip recently in another thread:
"Use the 10% rule when making tenons for threading with a die."
"Reduce the nominal tenon size by 10% of the thread pitch."
nominal tenon size: 14mm = .551
pitch: .8mm = .0135
10% = .00135
.551 - .00135 = .549
duncsuss
Member
Honestly, it is MUCH easier to stay with the measurement system of the tap & die.
In metric - a general rule is to make the tenon 0.1mm smaller than the nominal major diameter. So for your M14 x 0.8 x 3 die, make the tenon 13.9mm - and chamfer the end 2mm at 45 degrees so the die can glide on easier.
When you drill a hole to tap - use a drill bit that is diameter minus pitch: 14 - 0.8 = 13.2mm.
For the tenon - you can reduce the diameter a bit more if you feel comfortable doing so. I like to reduce it a little so the peaks of the threads are not sharp. It feels nicer, and because I polish the tenon before cutting the threads, the flat-tops are shiny so it looks nicer too.
In metric - a general rule is to make the tenon 0.1mm smaller than the nominal major diameter. So for your M14 x 0.8 x 3 die, make the tenon 13.9mm - and chamfer the end 2mm at 45 degrees so the die can glide on easier.
When you drill a hole to tap - use a drill bit that is diameter minus pitch: 14 - 0.8 = 13.2mm.
For the tenon - you can reduce the diameter a bit more if you feel comfortable doing so. I like to reduce it a little so the peaks of the threads are not sharp. It feels nicer, and because I polish the tenon before cutting the threads, the flat-tops are shiny so it looks nicer too.
PatrickR
Member
x2 - most lathes are metric the tap and dies are metric. It is much easier to simply work in metric, calculations to imperial is just extra work.
wimkluck
Member
Here is a quick guide. I have never understand why you calculate in inches. Metric is a lot easier.
| TAP MAAT | SNIJTAP | ||
| INCH | METRISCH | BOORMAAT | DECIMALE EQUIVALENT |
| 0-80 | 3/64 | .0469 | |
| M1.6 X 0.35 | 1.25mm | .0492 | |
| M1.8 X 0.35 | 1.45mm | .0571 | |
| 1-64 | 53 | .0595 | |
| 1-72 | 53 | .0595 | |
| M2 X 0.40 | 1.60mm | .0630 | |
| 2-56 | 50 | .0700 | |
| 2-64 | 50 | .0700 | |
| M2.2 X 0.45 | 1.75mm | .0689 | |
| M2.5 X 0.45 | 2.05mm | .0807 | |
| 3-48 | 47 | .0785 | |
| 3-56 | 46 | .0810 | |
| 4-40 | 43 | .0890 | |
| 4-48 | 42 | .0935 | |
| M3 X 0.50 | 2.50mm | .0984 | |
| 5-40 | 38 | .1015 | |
| 5-44 | 37 | .1040 | |
| M3.5 X 0.60 | 2.90mm | .1142 | |
| 6-32 | 36 | .1065 | |
| 6-40 | 33 | .1130 | |
| M4 X 0.70 | 3.30mm | .1299 | |
| 8-32 | 29 | .1360 | |
| 8-36 | 29 | .1360 | |
| M4.5 X 0.75 | 3.70mm | .1476 | |
| 10-24 | 26 | .1470 | |
| 10-32 | 21 | .1590 | |
| M5 X 0.80 | 4.20mm | .1654 | |
| 12-24 | 16 | .1770 | |
| 12-28 | 15 | .1800 | |
| M6 X 1.00 | 5.00mm | .1969 | |
| 1/4-20 | 7 | .2010 | |
| 1/4-28 | 3 | .2130 | |
| M7 X 1.00 | 6.00mm | .2362 | |
| 5/16-18 | F | .2570 | |
| M8 X 1.25 | 6.70mm | .2638 | |
| 5/16-24 | I | .2720 | |
| M8 X 1.0 | 7.00mm | .2756 | |
| 3/8-16 | 5/16 | .3125 | |
| 3/8-24 | Q | .3320 | |
| M10 X 1.50 | 8.50mm | .3346 | |
| M10 X 1.25 | 8.70mm | .3425 | |
| 7/16-14 | U | .3680 | |
| 7/16-20 | 25/64 | .3906 | |
| M12 X 1.75 | 10.20mm | .4016 | |
| 1/2-13 | 27/64 | .4219 | |
| M12 X 1.25 | 10.80mm | .4252 | |
| M14 X 2.00 | 12.00mm | .4224 | |
| 1/2-20 | 29/64 | .4531 | |
| 9/16-12 | 31/64 | .4844 | |
| 9/16-18 | 33/64 | .5156 | |
| 5/8-11 | 17/32 | .5312 | |
| 5/8-18 | 37/64 | .5781 | |
| M16 X 2.00 | 14.00mm | .5512 | |
| M16 X 1.50 | 14.50mm | .5906 | |
| M18 X 2.50 | 15.50mm | .6102 | |
| M18 X 1.50 | 16.50mm | .6496 | |
| 3/4-10 | 21/32 | .6562 | |
| 3/4-16 | 11/16 | .6875 | |
| M20 X 2.50 | 17.50mm | .6890 | |
| 45/64 | .7031 | ||
| 23/32 | .7188 | ||
| M20 X 1.50 | 18.50mm | .7283 | |
| M22 X 2.50 | 19.50mm | .7677 | |
| M22 X 1.50 | 20.50mm | .8071 | |
| 7/8-9 | 49/64 | .7656 | |
| 7/8-14 | 13/16 | .8125 | |
| M24 X 3.00 | 21.00mm | .8268 | |
| M24 X 2.00 | 22.00mm | .8661 | |
| 1-8 | 7/8 | .8750 | |
| 1-12 | 59/64 | .9219 | |
| M27 X 3.00 | 24.00mm | .9449 | |
| M27 X 2.00 | 25.00mm | .9843 | |
| 1-1/8-7 | 63/64 | .9844 | |
| M30 X 3.50 | 26.50mm | 1.0433 | |
| 1-1/8-12 | 1-3/64 | 1.0469 | |
| M30 X 2.00 | 28.00mm | 1.1024 | |
| 1-1/4-7 | 1-7/64 | 1.1094 | |
| M33 X 3.50 | 29.50mm | 1.1614 | |
| 1-1/4-12 | 1-11/64 | 1.1719 | |
| 1-3/8-6 | 1-7/32 | 1.2188 | |
| >M33 X 2.00 | 31.00mm | 1.2205 | |
| 1-3/8-12 | 1-19/64 | 1.2969 | |
| M36 X 4.00 | 32.00mm | 1.2598 | |
| M36 X 3.00 | 33.00mm | 1.2992 | |
| 1-1/2-6 | 1-11/32 | 1.3438 | |
| M39 X 4.00 | 35.00mm | 1.3780 | |
| 1-1/2-12 | 1-27/64 | 1.4219 | |
| M39 X 3.00 | 36.00mm | 1.4173 |