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Guide to CNC Tapping (manufacturing Threads)
Guide to CNC Tapping (manufacturing Threads)

This guide provides a comprehensive overview of CNC tapping, detailing the correct tap sizes and drilling techniques to ensure precision and efficiency in your machining process.

Updated over 4 months ago

CNC TAP CHART

Tapping is an essential machining process used to create threads inside holes, and understanding the correct dimensions and procedures is key to achieving precise results. This CNC Tap Chart Guide serves as a comprehensive reference for selecting the right tap sizes and drilling methods for various thread types. Whether you're working with coarse or fine metric threads, the guide helps you align taps accurately, maintain tool longevity with proper oil usage, and avoid common pitfalls such as tool overheating. Mastering the use of this chart ensures efficient and high-quality tapping in any CNC operation.

Using Tap Guides

Tap guides are an integral part in making a usable and straight tap. When using the lathe or the mill, the tap is already straight and centred. When manually aligning a tap, be careful, as a 90° tap guide is much more accurate than the human eye.

Using Oil

When drilling and tapping, it is crucial to use oil. It keeps the bits from squealing, makes the cut smoother, cleans out the chips, and keeps the drill and stock from overheating.

Pecking

Pecking helps ensure that bits don’t overheat and break when using them to drill or tap. Peck drilling involves drilling partway through a part, then retracting it to remove chips, simultaneously allowing the piece to cool. Rotating the handle a full turn then back a half turn is common practice. Whenever the bit or tap is backed out, remove as many chips as possible and add oil to the surface between the drill or tap and the workpiece. Hand Tapping Procedure 1. Select drill size from chart. When choosing a tap size, this chart is the first place to look

Metric Thread Table - Coarse Pitch (M1-M68)

Metric thread sizes, including the core diameter (d1/D1).

Nominal
Size

d=D
(mm)

pitch
(mm)

Root radius
(mm)

d2=D2

Pitch diameter
(mm)

d3 (Minor Diameter Male thread)
(mm)

D1 (Minor Diameter Female Thread)
(mm)

h3 (thread heigh male)
(mm)

H1 (Thread height female)
(mm)

Tap Drill
(mm)

M1

1

0.25

0.036

0.838

0.693

0.729

0.153

0.135

0.75

M1.1

1.1

0.25

0.036

0.938

0.793

0.829

0.153

0.135

0.85

M1.2

1.2

0.25

0.036

1.038

0.893

0.929

0.153

0.135

0.95

M1.4

1.4

0.3

0.043

1.205

1.032

1.075

0.184

0.162

1.1

M1.6

1.6

0.35

0.051

1.373

1.171

1.221

0.215

0.189

1.25

M1.8

1.8

0.35

0.051

1.573

1.371

1.421

0.215

0.189

1.45

M2

2

0.4

0.058

1.74

1.509

1.567

0.245

0.217

1.6

M2.2

2.2

0.45

0.065

1.908

1.648

1.713

0.276

0.244

1.75

M2.5

2.5

0.45

0.065

2.208

1.948

2.013

0.276

0.244

2.05

M3

3

0.5

0.072

2.675

2.387

2.459

0.307

0.271

2.5

M3.5

3.5

0.6

0.087

3.11

2.764

2.85

0.368

0.325

2.9

M4

4

0.7

0.101

3.545

3.141

3.242

0.429

0.379

3.3

M4.5

4.5

0.75

0.108

4.013

3.58

3.688

0.46

0.406

3.8

M5

5

0.8

0.115

4.48

4.019

4.134

0.491

0.433

4.2

M6

6

1

0.144

5.35

4.773

4.917

0.613

0.541

5

M7

7

1

0.144

6.35

5.773

5.917

0.613

0.541

6

M8

8

1.25

0.18

7.188

6.466

6.647

0.767

0.677

6.8

M9

9

1.25

0.18

8.188

7.466

7.647

0.767

0.677

7.8

M10

10

1.5

0.217

9.026

8.16

8.376

0.92

0.812

8.5

M11

11

1.5

0.217

10.026

9.16

9.376

0.92

0.812

9.5

M12

12

1.75

0.253

10.863

9.853

10.106

1.074

0.947

10.2

M14

14

2

0.289

12.701

11.546

11.835

1.227

1.083

12

M16

16

2

0.289

14.701

13.546

13.835

1.227

1.083

14

M18

18

2.5

0.361

16.376

14.933

15.394

1.534

1.353

15.5

M20

20

2.5

0.361

18.376

16.933

17.294

1.534

1.353

17.5

M22

22

2.5

0.361

20.376

18.933

19.294

1.534

1.353

19.5

M24

24

3

0.433

22.051

20.319

20.752

1.84

1.624

21

M27

27

3

0.433

25.051

23.319

23.752

1.84

1.624

24

M30

30

3.5

0.505

27.727

25.706

26.211

2.147

1.894

26.5

M33

33

3.5

0.505

30.727

28.706

29.211

2.147

1.894

29.5

M36

36

4

0.577

33.402

31.093

31.67

2.454

2.165

32

M39

39

4

0.577

36.402

34.093

34.67

2.454

2.165

35

M42

42

4.5

0.65

39.077

36.479

37.129

2.76

2.436

37.5

M48

48

5

0.722

44.752

41.866

42.857

3.067

2.706

43

M52

52

5

0.722

48.752

45.866

46.587

3.067

2.706

47

M56

56

5.5

0.794

52.428

49.252

50.046

3.374

2.977

50.5

M60

60

5.5

0.794

56.428

53.252

54.046

3.374

2.977

54.5

M64

64

6

0.866

60.103

56.639

57.505

3.681

3.248

58

M68

68

6

0.866

64.103

60.639

61.505

3.681

3.248

62

Metric Thread Table - Fine Pitch (M1-M64)

Metric thread sizes, including the core diameter (d1/D1). The table below shows fine thread sizes commonly available for different fine metric thread.

Nominal
Size

d=D
(mm)

pitch
(mm)

Root radius
(mm)

d2=D2

Pitch diameter
(mm)

d3 (Minor Diameter Male thread)
(mm)

D1 (Minor Diameter Female Thread)
(mm)

h3 (thread heigh male)
(mm)

H1 (Thread height female)
(mm)

Tap Drill
(mm)

M1.0x0.2

1

0.2

0.029

0.87

0.755

0.783

0.123

0.108

0.8

M1.1x0.2

1.1

0.2

0.029

0.97

0.855

0.883

0.123

0.108

0.9

M1.2x0.2

1.2

0.2

0.029

1.07

0.955

0.983

0.123

0.108

1

M1.4x0.2

1.4

0.2

0.029

1.27

1.155

1.183

0.123

0.108

1.2

M1.6x0.2

1.6

0.2

0.029

1.47

1.355

1.383

0.123

0.108

1.4

M1.8x0.2

1.8

0.2

0.029

1.67

1.555

1.583

0.123

0.108

1.6

M2x0.25

2

0.25

0.036

1.838

1.693

1.729

0.153

0.135

1.75

M2.2x0.25

2.2

0.25

0.036

2.038

1.893

1.929

0.153

0.135

1.95

M2.5x0.35

2.5

0.35

0.051

2.273

2.071

2.121

0.215

0.189

2.1

M3x0.35

3

0.35

0.051

2.773

2.571

2.621

0.215

0.189

2.6

M3.5x0.35

3.5

0.35

0.051

3.273

3.071

3.121

0.215

0.189

3.1

M4x0.5

4

0.5

0.072

3.675

3.387

3.459

0.307

0.271

3.5

M4.5x0.5

4.5

0.5

0.072

4.175

3.887

3.959

0.307

0.271

4

M5x0.5

5

0.5

0.072

4.675

4.387

4.459

0.307

0.271

4.5

M5.5x0.5

5.5

0.5

0.072

5.175

4.887

4.959

0.307

0.271

5

M6x0.75

6

0.75

0.108

5.513

5.08

5.188

0.46

0.406

5.2

M7x0.75

7

0.75

0.108

6.513

6.08

6.188

0.46

0.406

6.2

M8x0.75

8

0.75

0.108

7.513

7.08

7.188

0.46

0.406

7.2

M8x1.0

8

1

0.144

7.35

6.773

6.917

0.613

0.541

7

M9x0.75

9

0.75

0.108

8.513

8.08

8.188

0.46

0.406

8.2

M9x1.0

9

1

0.144

8.35

7.773

7.917

0.613

0.541

8

M10x0.75

10

0.75

0.108

9.513

9.08

9.188

0.46

0.406

9.2

M10x1.0

10

1

0.144

9.35

8.773

8.917

0.613

0.541

9

M10x1.25

10

1.25

0.18

9.188

8.466

8.647

0.767

0.677

8.8

M11x0.75

11

0.75

0.108

10.513

10.08

10.188

0.46

0.406

10.2

M11x1.0

11

1

0.144

10.35

9.773

9.917

0.613

0.541

10

M12x1.0

12

1

0.144

11.35

10.773

10.917

0.613

0.541

11

M12x1.25

12

1.25

0.18

11.188

10.466

10.647

0.767

0.677

10.8

M12x1.5

12

1.5

0.217

11.026

10.16

10.376

0.92

0.812

10.5

Nomial
Size

d=D
(mm)

p
(mm)

r
(mm)

d2=D2
(mm)

d3
(mm)

D1
(mm)

h3
(mm)

H1
(mm)

Tap Drill
(mm)

M14x1.0

14

1

0.144

13.35

12.773

12.917

0.613

0.541

13

M14x1.25

14

1.25

0.18

13.188

12.466

12.647

0.767

0.677

12.8

M14x1.5

14

1.5

0.217

13.026

12.16

12.376

0.92

0.812

12.5

M15x1.0

15

1

0.144

14.35

13.773

13.917

0.613

0.541

14

M15x1.5

15

1.5

0.217

14.026

13.16

13.376

0.92

0.812

13.5

M16x1.0

16

1

0.144

15.35

14.773

14.917

0.613

0.541

15

M16x1.5

16

1.5

0.217

15.026

14.16

14.376

0.92

0.812

14.5

M17x1.0

17

1

0.144

16.35

15.773

15.917

0.613

0.541

16

M17x1.5

17

1.5

0.217

16.026

15.16

15.376

0.92

0.812

15.5

M18x1.0

18

1

0.144

17.35

16.773

16.917

0.613

0.541

17

M18x1.5

18

1.5

0.217

17.026

16.16

16.376

0.92

0.812

16.5

M18x2.0

18

2

0.289

16.701

15.546

15.835

1.227

1.083

16

M20x1.0

20

1

0.144

19.35

18.773

18.917

0.613

0.541

19

M20x1.5

20

1.5

0.217

19.026

18.16

18.376

0.92

0.812

18.5

M20x2.0

20

2

0.289

18.701

17.546

17.835

1.227

1.083

18

M22x1.0

22

1

0.144

21.35

20.773

20.917

0.613

0.541

21

M22x1.5

22

1.5

0.217

21.026

20.16

20.376

0.92

0.812

20.5

M22x2.0

22

2

0.289

20.701

19.546

19.835

1.227

1.083

20

M24x1.0

24

1

0.144

23.35

22.773

22.917

0.613

0.541

23

M24x1.5

24

1.5

0.217

23.026

22.16

22.376

0.92

0.812

22.5

M24x2.0

24

2

0.289

22.701

21.546

21.835

1.227

1.083

22

M25x1.0

25

1

0.144

24.35

23.773

23.917

0.613

0.541

24

M25x1.5

25

1.5

0.217

24.026

23.16

23.376

0.92

0.812

23.5

M25x2.0

25

2

0.289

23.701

22.546

22.835

1.227

1.083

23

M27x1.0

27

1

0.144

26.35

25.773

25.917

0.613

0.541

26

M27x1.5

27

1.5

0.217

26.026

25.16

25.376

0.92

0.812

25.5

M27x2.0

27

2

0.289

25.701

24.546

24.835

1.227

1.083

25

M28x1.0

28

1

0.144

27.35

26.773

26.917

0.613

0.541

27

M28x1.5

28

1.5

0.217

27.026

26.16

26.376

0.92

0.812

26.5

M28x2.0

28

2

0.289

26.701

25.546

25.835

1.227

1.083

26

Nomial
Size

d=D
(mm)

p
(mm)

r
(mm)

d2=D2
(mm)

d3
(mm)

D1
(mm)

h3
(mm)

H1
(mm)

Tap Drill
(mm)

M30x1.0

30

1

0.144

29.35

28.773

28.917

0.613

0.541

29

M30x1.5

30

1.5

0.217

29.026

28.16

28.376

0.92

0.812

28.5

M30x2.0

30

2

0.289

28.701

27.546

27.835

1.227

1.083

28

M30x3.0

30

3

0.433

28.051

26.319

26.752

1.84

1.624

27

M32x1.5

32

1.5

0.217

31.026

30.16

30.376

0.92

0.812

30.5

M32x2.0

32

2

0.289

30.701

29.546

29.835

1.227

1.083

30

M33x1.5

33

1.5

0.217

32.026

31.16

31.376

0.92

0.812

31.5

M33x2.0

33

2

0.289

31.701

30.546

30.835

1.227

1.083

31

M33x3.0

33

3

0.433

31.051

29.319

29.752

1.84

1.624

30

M35x1.5

35

1.5

0.217

34.026

33.16

33.376

0.92

0.812

33.5

M35x2.0

35

2

0.289

33.701

32.546

32.835

1.227

1.083

33

M36x1.5

36

1.5

0.217

35.026

34.16

34.376

0.92

0.812

34.5

M36x2.0

36

2

0.289

34.701

33.546

33.835

1.227

1.083

34

M36x3.0

36

3

0.433

34.051

32.319

32.752

1.84

1.624

33

M39x1.5

39

1.5

0.217

38.026

37.16

37.376

0.92

0.812

37.5

M39x2.0

39

2

0.289

37.701

36.546

36.835

1.227

1.083

37

M39x3.0

39

3

0.433

37.051

35.319

35.752

1.84

1.624

36

M40x1.5

40

1.5

0.217

39.026

38.16

38.376

0.92

0.812

38.5

M40x2.0

40

2

0.289

38.701

37.546

37.835

1.227

1.083

38

M40x3.0

40

3

0.433

38.051

36.619

36.752

1.84

1.624

37

M42x1.5

42

1.5

0.217

41.026

40.16

40.376

0.92

0.812

40.5

M42x2.0

42

2

0.289

40.701

39.546

39.835

1.227

1.083

40

M42x3.0

42

3

0.433

40.051

38.319

38.752

1.84

1.624

39

M42x4.0

42

4

0.577

39.402

37.093

37.67

2.454

2.165

38

M45x1.5

45

1.5

0.217

44.026

43.16

43.376

0.92

0.812

43.5

M45x2.0

45

2

0.289

43.701

42.546

42.835

1.227

1.083

43

M45x3.0

45

3

0.433

43.051

41.319

41.752

1.84

1.624

42

M45x4.0

45

4

0.577

42.402

40.093

40.67

2.454

2.165

41

M48x1.5

48

1.5

0.217

47.026

46.16

46.376

0.92

0.812

46.5

M48x2.0

48

2

0.289

46.701

45.546

45.835

1.227

1.083

46

M48x3.0

48

3

0.433

46.051

44.319

44.752

1.84

1.624

45

M48x4.0

48

4

0.577

45.402

43.093

43.67

2.454

2.165

44

Nomial
Size

d=D
(mm)

p
(mm)

r
(mm)

d2=D2
(mm)

d3
(mm)

D1
(mm)

h3
(mm)

H1
(mm)

Tap Drill
(mm)

M50x1.5

50

1.5

0.217

49.026

48.16

48.376

0.92

0.812

48.5

M50x2.0

50

2

0.289

48.701

47.546

47.835

1.227

1.083

48

M50x3.0

50

3

0.433

48.051

46.319

46.752

1.84

1.624

47

M52x1.5

52

1.5

0.217

51.026

50.16

50.376

0.92

0.812

50.5

M52x2.0

52

2

0.289

50.701

49.546

49.835

1.227

1.083

50

M52x3.0

52

3

0.433

50.051

48.319

48.752

1.84

1.624

49

M52x4.0

52

4

0.577

49.402

47.093

47.67

2.454

2.165

48

M55x1.5

55

1.5

0.217

54.026

53.16

53.376

0.92

0.812

53.5

M55x2.0

55

2

0.289

53.701

52.546

52.835

1.227

1.083

53

M55x3.0

55

3

0.433

53.051

51.319

51.752

1.84

1.624

52

M55x4.0

55

4

0.577

52.402

50.093

50.67

2.454

2.165

51

M56x1.5

56

1.5

0.217

55.026

54.16

54.376

0.92

0.812

54.5

M56x2.0

56

2

0.289

54.701

43.546

53.835

1.227

1.083

54

M56x3.0

56

3

0.433

54.051

52.319

52.752

1.84

1.624

53

M56x4.0

56

4

0.577

53.402

51.903

51.67

2.454

2.165

52

M58x1.5

58

1.5

0.217

57.026

56.16

56.376

0.92

0.812

56.5

M58x2.0

58

2

0.289

56.701

55.546

55.835

1.227

1.083

56

M58x3.0

58

3

0.433

56.051

54.319

54.752

1.84

1.624

55

M58x4.0

58

4

0.577

55.402

53.093

53.67

2.454

2.165

54

M60x1.5

60

1.5

0.217

59.026

58.16

58.376

0.92

0.812

58.5

M60x2.0

60

2

0.289

58.701

57.546

57.835

1.227

1.083

58

M60x3.0

60

3

0.433

58.051

56.319

56.752

1.84

1.624

57

M60x4.0

60

4

0.577

57.402

55.093

55.67

2.454

2.165

56

M62x1.5

62

1.5

0.217

61.026

60.16

60.376

0.92

0.812

60.5

M62x2.0

62

2

0.289

60.701

59.546

59.835

1.227

1.083

60

M62x3.0

62

3

0.433

60.051

58.319

58.752

1.84

1.624

59

M62x4.0

62

4

0.577

59.402

57.093

57.67

2.454

2.165

58

M64x1.5

64

1.5

0.217

63.026

62.16

62.376

0.92

0.812

62.5

M64x2.0

64

2

0.289

62.701

61.546

61.835

1.227

1.083

62

M64x3.0

64

3

0.433

62.051

60.319

60.752

1.84

1.624

61

M64x4.0

64

4

0.577

61.402

59.093

59.67

2.454

2.165

60

BSPP / BSPT Thread Chart

SIZE

TPI

MAJOR (EXT)

MINOR (INT)

TAP DRILL

1/8"

28

9.728

8.566

8.70

1/4"

19

13.157

11.445

11.60

3/8"

19

16.662

14.950

15.00

1/2"

14

20.955

18.631

19.00

5/8"

14

22.911

20.587

20.75

3/4"

14

26.441

24.117

24.50

7/8"

14

30.201

27.877

28.00

1"

11

33.249

31.770

30.50

11/8"

11

37.897

34.939

35.00

11/4"

11

41.910

38.952

39.50

13/8"

11

44.323

41.365

41.50

11/2"

11

47.803

44.845

45.00

13/4"

11

53.746

50.788

51.00

2"

11

59.614

56.656

57.00

21/4"

11

65.710

62.752

63.00

21/2"

11

75.184

72.226

72.50

23/4

11

81.534

78.576

79.00

3"

11

87.884

84.926

85.50

31/4"

11

93.980

91.501

91.00

31/2"

11

100.330

97.372

97.75

33/4"

11

106.680

103.722

104.00

4"

11

113.030

110.072

110.50

41/2"

11

125.730

122.772

123.00

5"

11

138.430

135.472

136.00

51/2"

11

151.130

148.172

148.50

6"

11

163.830

160.872

161.50

Related Articles
Guide to Drill Sizes
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