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Tap & Drill Chart

TapandDrillChart.pdf

Tap and Drill Chart
(Recommended tap drill to use for 75% depth of thread)

To Tap this Size Screw   Or Bolt: Use This Drill Bit: (Closest Fractional:) Decimal Inches
0-80 NF 3/64″ 3/64″ .0469
0-80 NF 3/64″ 3/64″ .0469
1-64 NC #53 .0595
1-72 NF #53 1/16″ .0595
2-56 NC #50 .0700
2-64 NF #50 .0700
3-48 NC #47 5/64″ .0785
3-56 NF #45 .0820
4-36 NS #44 .0860
4-40 NC #43 3/32″ .0890
4-48 NF #42 3/32″ .0935
3mm- .060mm 2.5mm .0984
1/8-40 NS #38 .1015
5-40 NC #38 .1015
5-44 NF #37 .1040
6-32 NC #35 7/64″ .1100
6-36 NS #34 .1110
6-40 NF #33 .1130
6-48 NS #31 .1200
4mm-0.70mm 3.4mm .1338
4mm-.075mm 3.4mm .1338
8-32 NC #29 .1360
8-36 NF #29 9/64″ .1360
8-40 NS #28 .1405
3/16-24 NS #26 .1470
10-24 NC #25 5/32″ .1495
3/16-32 NS #22 .1570
10-32 NF #21 5/32″ .1590
5mm-.090mm 4.2mm .1653
5mm-.080mm 4.3mm .1693
12-24 NC #16 11/64″ .1770
12-28 NF #14 3/16″ .1820
12-32 NEF #13 .1850
14-20 NS #10 .1935
1//4-20 NC #7 13/64″ .2010
14-24 NS #7 .2010
6mm-1.00mm 5.2mm .2047
1/4-24 NS #4 .2090
1/4-28 NF #3 7/32″ .2130
1/4-32 NEF 7/32″ 7/32″ .2188
1/4-40 NS #1 .2280
7mm-1.00mm 6.1mm 15/64″ .2401
5/16-18 NC Ltr.F 17/64″ .2570
8mm-1.25mm 6.9mm 17/64″ .2716
5/16-24 NF Ltr.I .2720
8mm-1.00mm 7.1mm .2795
5/16-32 NEF 9/32″ 9/32″ .2812
9mm-1.25mm 7.9mm .3110
3/8-16 NC 5/16″ 5/16″ .3125
9mm-1.00mm 8.1mm .3189
9mm-0.75mm 8.3mm .3268
3/8-24 NF Ltr.Q 21/64″ .3320
10mm- 1.50mm 8.7mm .3425
10mm- 1.25mm 8.9mm 11/32″ .3503
10mm- 1.00mm* 9.1mm .3583
7/16- 14 NC Ltr.U 23/64″ .3680
11mm 1.50mm 9.7mm .3818
7/16-20 NF 25/64″ 25/64″ .3906
12mm- 1.75mm 10.5mm .4133
12mm- 1.50mm 10.7mm 27/64″ .4212
1/2-13 NC 27/64″ 27/64″ .4219
12mm- 1.25mm* 10.9mm 27/64″ .4291
1/2-20 NF 29/64″ 29/64″ .4531
1/2-24 NS 29/64″ 29/64″ .4531
14mm-2.00mm 12.2mm .4803
9/16-12 NC 31/64″ 31/64″ .4844
14mm- 1.50mm 12.7mm .4999
14mm-1.25mm* 12.8mm .5039
9/16-18 NF 33/64″ 33/64″ .5156
5/8-11 NC 17/32″ 17/32″ .5312
16mm-2.00mm 14.2mm 35/64″ .5590
5/8-18 NF 37/64″ 37/64″ .5781
16mm- 1.50mm 14.7mm .5787
11/16-11 NS 19/32″ 19/32″ .5938
18mm-2.50mm 15.8mm 39/64″ .5220
11/16-16 NS 5/8″ 5/8″ .6250
3/4-10 NC 21/32″ 21/32″ .6562
18mm-1.50mm* 16.8mm .6614
3/4-16 NF 11/16″ 11/16″ .6875
20mm-2.50mm 17.8mm 11/16″ .7008
7/8-9 NC 49/64″ 49/64″ .7656
7/8-14 NF 13/16″ 13/16″ .8125
22mm-1.50mm 20.9mm .8228
7/8-18 NS* 53/64″ 53/64″ .8281
24mm-3.00mm 21.4mm 53/64″ .8425
1.8 NC 7/8″ 7/8″ .8750
24mm-2.00mm 22.3mm .8779
1.12 NF 59/64″ 59/64″ .9219
1-14 NS 15/16″ 15/16″ .9375
1  1/8-7 NC 63/64″ 63/64″ .9844
1 1/8-12 NF 1 3/64″ 1 3/64″ 1.0469
1 1/4-7 NC 1 7/64″ 1 7/64″ 1.1094
1 1/4-12 NF 1 11/64″ 1 11/64″ 1.1719
1 3/8-6 NC 1 7/32″ 1 7/32″ 1.2188
1 3/8-12 NF 1 19/64″ 1 19/64″ 1.2969
1 1/2-6 NC 1 11/32″ 1 11/32″ 1.3438
1 1/2″-12 NF 1 27/64″ 1 27/64″ 1.4219
*These Sizes Are Spark Plug Taps

2 Responses to "Tap & Drill Chart"

Andy

August 23, 2014 at 8:53 am

Hi. I’m have a brass gear shift knob on a round steel shaft, and the coupling which brings the interior dimension of the knob socket down to the exterior dimension of the shaft is made of copper (actually a piece of plumbing supply that fit the bill perfectly). I had it installed on the shaft years ago. It is held in place with two set screws. Over time, the softer copper has eroded so that the threads holding one of the set screws are mostly gone. (Curiously the other set screw is as tight as the day it went in). The hole either needs to be re-tapped and a larger set screw used, or it needs to be replaced. I’d rather drill a new hole so I can keep the same size of screw. Besides, since I have to do this anyway, I’d like to drill two holes so that the shaft is gripped at 2, 6 and 10 o’clock instead of just 12 and 6 like it was. A local machinist did it for me back in the day but I want to do it myself this time, and I’ve never tapped a screw before. Existing set screw (the good one) is 4mm but is too tiny for me to read the thread pitch or count, which I think is what your chart wants when it says 0.70mm or 0.75mm. I figured I’d ask the guy at the store to set me up with the correct tap drill & screw at the same time, but I sort of like to want to know more before I do. Can you make any suggestions? And, thinking of using Permatex blue when I re-install the knob… good idea or not? thanks guys

AutoDrill

August 23, 2014 at 3:16 pm

Hello,

We could likely help you if you were local as we have a thread pitch gauge set to check fasteners, etc. However, seeing that there is likely a good distance between us, we would suggest purchasing the tap and set screw (as well as potentially the tap drill size) all at the same time to help guarantee success.

If this is a permanent installation, then use a strong, permanent Loctite type material to keep it in place. Otherwise, consider using something such as Vibra-Tite as it goes on in liquid form and then hardens up but can be removed later on if needed.

Much success to you!

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