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Tapping Internal Threads

The Importance of Choosing the Right Tap

For precision cutting, choosing the right tool is essential. Taps, which are used to create internal threads on a workpiece, provide accuracy, customization, and cost-efficiency across a wide range of machining and manufacturing tasks. With the right tap, threads are formed with precision, ensuring excellent engagement, durability, and wear resistance. Taps come in a variety of materials, coatings, flute designs, lengths, and other specifications. To help you select the ideal tap for your needs, the following provides an overview of each specification, ensuring optimal efficiency and productivity.

Order HSS Taps Order Nitro Spiral Point Taps Order Nitro Spiral Flute Taps

Determining the Application

 

Hand tapping requires manual control and is best-suited for low-volume or delicate tasks where feel and on-the-fly adjustments are crucial. This method offers flexibility in tight or hard-to-reach spaces but is a slower, manual process.

Hand tap vs machine tap

Machine tapping, executed with a drill press or tapping machine, with specialized designs to efficiently handle chips, is ideal for high-speed, consistent threading in high volume, offering greater precision and uniformity while reducing operator fatigue and effortlessly handling tougher materials.

Determining the Type of Hole

When choosing what taps are right for you, you will need to consider the type of hole you're trying to make; whether you'll be hand or machine tapping, and the materials on which you'll be working.

• A blind hole does not go all the way through the material.

• A through hole goes completely through the material.

Through and blind holes

Tap Geometries

For Hand Tapping of Through and Blind Holes

Taper taps
Plug taps
Bottoming taps
Tap sets

For Machine Tapping of Through and Blind Holes

Spiral point taps
Spiral flute taps

Tapered Taps for Threading Pipe

Tapered pipe taps

Choosing the Right Taps

  Hand Taps Spiral Point Taps Spiral Flute Taps Pipe Taps
Application Wrench (manual) Machine Machine For tapping into pipes and fittings
Description Hand taps have 3 standard
chamfer geometries including
taper, plug, and bottoming.
They have straight flutes and
are the most popular and
versatile styles of
taps in general machine tapping
operations.		 An additional grind on the tip of the tap propels the
chips ahead causing less
load and clogging in the flutes.
The combination of forward chip
ejection and reduced cutting
torque allows for faster and
more efficient tapping in through
hole applications
 The design of spiral flute
taps is conducive to improved chip flow. The flutes pull the
chips out of the workpiece,
which reduces the changes of tap
breakage in blind hole applications.
Featuring helical flutes that propel the chips upward and allows for better coolant flow to the cutting area, helping
to dissipate heat and prolong tool life.
 Pipe taps are specialized tools used for tapping NPT pipe threads to mate with threaded pipe and fittings that conform to standard pipe
sizes and provide tight,
leak-proof connections.
Chip Removal Manual chip breakage Chips break automatically
- Evacuates chips down		 Chips break automatically
- Pulls chips out		 Manual chip breakage
Type of Hole Through (for Taper and Plug),
     Blind (for Taper, Plug and Bottoming)		 Blind for Plug Blind for Bottoming Through for Plug

Selecting the Tap Based on the Material

The next step is assessing the material you'll be working on. Once you know the material, you'll be able to match it with the appropriate tap material and coating.

Selecting materials

Drill Size Decimal Equivalent Chart

Drill Size Decimal Equivalent mm Drill Size Decimal Equivalent mm Drill Size Decimal Equivalent mm
80 0.0135 0.343 31 0.12 3.048 5/16 0.3125 7.938
79 0.0145 0.368 1/8 0.125 3.175 O 0.316 8.026
1/64 0.0156 0.396 30 0.1285 3.264 P 0.323 8.204
78 0.016 0.406 29 0.136 3.454 21/64 0.3281 8.334
77 0.018 0.457 28 0.1405 3.569 Q 0.332 8.433
76 0.02 0.508 9/64 0.1406 3.571 R 0.339 8.611
75 0.021 0.533 27 0.144 3.658 11/32 0.3438 8.733
74 0.0225 0.572 26 0.147 3.734 S 0.348 8.839
73 0.024 0.610 25 0.1495 3.797 T 0.358 9.093
72 0.025 0.635 24 0.152 3.861 23/64 0.3594 9.129
71 0.026 0.660 23 0.154 3.912 U 0.368 9.347
70 0.028 0.711 5/32 0.15625 3.969 3/8 0.375 9.525
69 0.0292 0.742 22 0.157 3.988 V 0.377 9.576
68 0.031 0.787 21 0.159 4.039 W 0.386 9.804
1/32 0.03125 0.794 20 0.161 4.089 25/64 0.3906 9.921
67 0.032 0.813 19 0.166 4.216 X 0.397 10.084
66 0.033 0.838 18 0.1695 4.305 Y 0.404 10.262
65 0.035 0.889 11/64 0.1719 4.366 13/32 0.40625 10.319
64 0.036 0.914 17 0.173 4.394 Z 0.413 10.490
63 0.037 0.940 16 0.177 4.496 27/64 0.4219 10.716
62 0.038 0.965 15 0.18 4.572 7/16 0.4375 11.113
61 0.039 0.991 14 0.182 4.623 29/64 0.4531 11.509
60 0.04 1.016 13 0.185 4.699 15/32 0.4688 11.908
59 0.041 1.041 3/16 0.1875 4.763 31/64 0.4844 12.304
58 0.042 1.067 12 0.189 4.801 1/2 0.5 12.700
57 0.043 1.092 11 0.191 4.851 33/64 0.5156 13.096
56 0.0465 1.181 10 0.1935 4.915 17/32 0.53125 13.494
3/64 0.0469 1.191 9 0.196 4.978 35/64 0.5469 13.891
55 0.052 1.321 8 0.199 5.055 9/16 0.5625 14.288
54 0.055 1.397 7 0.201 5.105 37/64 0.5781 14.684
53 0.0595 1.511 13/64 0.2031 5.159 19/32 0.5938 15.083
1/16 0.0625 1.588 6 0.204 5.182 39/64 0.6094 15.479
52 0.0635 1.613 5 0.2055 5.220 5/8 0.625 15.875
51 0.067 1.702 4 0.209 5.309 41/64 0.6406 16.271
50 0.07 1.778 3 0.213 5.410 21/32 0.65625 16.669
49 0.073 1.854 7/32 0.2188 5.558 43/64 0.6719 17.066
48 0.076 1.930 2 0.221 5.613 11/16 0.6875 17.463
5/64 0.0781 1.984 1 0.228 5.791 45/64 0.7031 17.859
47 0.0785 1.994 A 0.234 5.944 23/32 0.7188 18.258
46 0.081 2.057 15/64 0.2344 5.954 47/64 0.7344 18.654
45 0.082 2.083 B 0.238 6.045 3/4 0.75 19.050
44 0.086 2.184 C 0.242 6.147 49/64 0.7656 19.446
43 0.089 2.261 D 0.246 6.248 25/32 0.78125 19.844
42 0.0935 2.375 1/4 (E) 0.25 6.350 51/64 0.7969 20.241
3/32 0.0938 2.383 F 0.257 6.528 13/16 0.8125 20.638
41 0.096 2.438 G 0.261 6.629 53/64 0.8281 21.034
40 0.098 2.489 17/64 0.2656 6.746 27/32 0.8438 21.433
39 0.0995 2.527 H 0.266 6.756 55/64 0.8594 21.829
38 0.1015 2.578 I 0.272 6.909 7/8 0.875 22.225
37 0.104 2.642 J 0.277 7.036 57/64 0.8906 22.621
36 0.1065 2.705 K 0.281 7.137 29/32 0.90625 23.019
7/64 0.1094 2.779 9/32 0.28125 7.144 59/64 0.9219 23.416
35 0.11 2.794 L 0.29 7.366 15/16 0.9375 23.813
34 0.111 2.819 M 0.295 7.493 61/64 0.9531 24.209
33 0.113 2.870 19/64 0.2969 7.541 31/32 0.9688 24.608
32 0.116 2.946 N 0.302 7.671 63/64 0.9844 25.004

Tap Drill Size Chart

Tap Size Drill Size Probable % Thread
M3-0.5 40 70-79
5-40 38 65-72
5-44 37 63-71
M3.5-0.6 33 72-81
6-32 36 71-78
6-40 33 69-77
M4-0.7 3.25 mm 74-82
8-32 29 62-69
8-36 29 70-78
10-24 25 69-75
10-32 21 68-76
M5-0.8 4.2 mm 69-77
12-24 16 66-72
12-28 15 70-78
M6-1.0 10 76-84
1/4-20 7 70-75
1/4-28 3 72-80
5/16-18 F 72-77
5/16-24 I 67-75
M8-1.25 6.7 mm 74-80
3/8-16 5/16 72-77
3/8-24 Q 71-79
M10-1.50 8.4 mm 76-82
7/16-14 U 70-75
7/16-20 25/64 65-72
M12-1.75 13/32 69-74
1/2-13 27/64 73-78
1/2-20 29/64 65-72
M14-2.0 15/32 76-81
9/16-12 31/64 68-72
9/16-18 33/64 58-65
5/8-11 17/32 75-79
5/8-18 37/64 58-65
M16-2.0 35/64 76-81
3/4-10 21/32 68-72
3/4-16 11/16 71-77
M20-2.5 11/16 74-78
7/8-9 49/64 72-76
7/8-14 13/16 62-67
M24-3.0 53/64 72-76
1-8 7/8 73-77
1-12 59/64 67-72
1-14 15/16 61-67
1-1/8-7 63/64 72-76
1-1/8-8 1 76
1-1/8-12 1-3/16 66-72
M30-3.5 1-3/64 75
1-1/4-7 1-7/64 76
1-1/4-8 1-1/8 76
1-1/4-12 1-11/64 72
1-3/8-6 1-7/32 72
1-3/8-12 1-19/64 72
M36-4.0 1-1/4 82
1-1/2-6 1-11/32 72
1-1/2-8 1-3/8 76
1-1/2-12 1-27/64 72
NPT Tap Size Taper Pipe Drill Size Straight Pipe Drill Size
1/8-27 R 11/32
1/4-18 7/16 7/16
3/8-18 37/64 37/64
1/2-14 45/64 23/32
3/4-14 59/64 59/64
1-11.5 1-5/32 1-5/32
1-1/4-11.5 1-1/2 1-1/2
1-1/2-11.5 1-47/64 1-3/4
2-11.5 2-7/32 2-7/32