ASME B18.3.1M Socket Head Cap Screws (Metric) Dimensions

ASME B18.3.1M Metric Socket Head Cap Screws Dimensions

Metric Series Dimensions for Socket Head Cap Screws

ASME B18.3.1M standard provides dimensional and technical specifications for metric socket head cap screws, ensuring compatibility in metric-based systems and international applications. It includes details on head size, socket dimensions, thread pitch, and tolerances. This page offers detailed ASME B18.3.1M metric dimensions, along with size charts and engineering references.

Metric Socket Head Cap Screw Dimensions, Lengths, and Thread Tolerances

Nom. Sizeand Thread Pitch	Body Diameter, D	Head Diameter A	Head Height H	Chamferor Radius S	Hexagon Socket Size^a J	Spline Socket Size^a M	Key Engagement T	Transition Dia. B^a
M1.6 × 0.35	1.6	1.46	3	2.87	1.6	1.52	0.16	1.5	1.829	0.8	2
M2 × 0.4	2	1.86	3.8	3.65	2	1.91	0.2	1.5	1.829	1	2.6
M2.5 × 0.45	2.5	2.36	4.5	4.33	2.5	2.4	0.25	2	2.438	1.25	3.1
M3 × 0.5	3	2.86	5.5	5.32	3	2.89	0.3	2.5	2.819	1.5	3.6
M4 × 0.7	4	3.82	7	6.8	4	3.88	0.4	3	3.378	2	4.7
M5 × 0.8	5	4.82	8.5	8.27	5	4.86	0.5	4	4.648	2.5	5.7
M6 × 1	6	5.82	10	9.74	6	5.85	0.6	5	5.486	3	6.8
M8 × 1.25	8	7.78	13	12.7	8	7.83	0.8	6	7.391	4	9.2
M10 × 1.5	10	9.78	16	15.67	10	9.81	1	8	...	5	11.2
M12 × 1.75	12	11.73	18	17.63	12	11.79	1.2	10	...	6	14.2
M14 × 2^b	14	13.73	21	20.6	14	13.77	1.4	12	...	7	16.2
M16 × 2	16	15.73	24	23.58	16	15.76	1.6	14	...	8	18.2
M20 × 2.5	20	19.67	30	29.53	20	19.73	2	17	...	10	22.4
M24 × 3	24	23.67	36	35.48	24	23.7	2.4	19	...	12	26.4
M30 × 3.5	30	29.67	45	44.42	30	29.67	3	22	...	15	33.4
M36 × 4	36	35.61	54	53.37	36	35.64	3.6	27	...	18	39.4
M42 × 4.5	42	41.61	63	62.31	42	41.61	4.2	32	...	21	45.6
M48 × 5	48	47.61	72	71.27	48	47.58	4.8	36	...	24	52.6
a See also Table 25. b The M14 ×2 size is not recommended for use in new designs. All dimensions are in millimeters LG is grip length and LB is body length. For length of complete thread. For additional manufacturing and acceptance specifications, see ASME B18.3.1M-1986.

Nom. Sizeand Thread Pitch

Body Diameter, D

Head Diameter A

Head Height H

Chamferor Radius S

Hexagon Socket Size^a J

Spline Socket Size^a M

Key Engagement T

Transition Dia. B^a

Max

Min.

Max

Min.

Max

Min.

Max

Nom.

Min.

Max

M1.6 × 0.35

1.6

1.46

2.87

1.6

1.52

0.16

1.5

1.829

0.8

M2 × 0.4

1.86

3.8

3.65

1.91

0.2

1.5

1.829

2.6

M2.5 × 0.45

2.5

2.36

4.5

4.33

2.5

2.4

0.25

2.438

1.25

3.1

M3 × 0.5

2.86

5.5

5.32

2.89

0.3

2.5

2.819

1.5

3.6

M4 × 0.7

3.82

6.8

3.88

0.4

3.378

4.7

M5 × 0.8

4.82

8.5

8.27

4.86

0.5

4.648

2.5

5.7

M6 × 1

5.82

9.74

5.85

0.6

5.486

6.8

M8 × 1.25

7.78

12.7

7.83

0.8

7.391

9.2

M10 × 1.5

9.78

15.67

9.81

...

11.2

M12 × 1.75

11.73

17.63

11.79

1.2

...

14.2

M14 × 2^b

13.73

20.6

13.77

1.4

...

16.2

M16 × 2

15.73

23.58

15.76

1.6

...

18.2

M20 × 2.5

19.67

29.53

19.73

...

22.4

M24 × 3

23.67

35.48

23.7

2.4

...

26.4

M30 × 3.5

29.67

44.42

29.67

...

33.4

M36 × 4

35.61

53.37

35.64

3.6

...

39.4

M42 × 4.5

41.61

62.31

41.61

4.2

...

45.6

M48 × 5

47.61

71.27

47.58

4.8

...

52.6

a See also Table 25.
b The M14 ×2 size is not recommended for use in new designs.
All dimensions are in millimeters
LG is grip length and LB is body length. For length of complete thread.
For additional manufacturing and acceptance specifications, see ASME B18.3.1M-1986.

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ASME B18.3.1M Metric Socket Head Cap Screws Dimensions

Metric Socket Head Cap Screw Dimensions, Lengths, and Thread Tolerances

Related Specifications

Surface Treatments

Certifications

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