Table 2. British Standard Slotted Raised Countersunk Head Machine Screws—Metric Series BS 4183:1967 (obsolescent)
Height of Raised Portion f
Head Diameter D
Head Height k
Thread Length b
Thread Run-out a
Head Radius R
Slot Width n
Slot Depth t
Radius Under Head r b
Nominal Size d a
Max. (Theor. Sharp) 2 d
Min. 1.75 d
Max. 0.5 d
Min. 0.45 d
Nom. 0.25 d 0.25
Max. 0.5 d 0.50 0.60 0.70 0.80 1.00 1.10 1.25 1.50 1.75 2.00 2.25 2.50 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00
Min. 0.4 d 0.40 0.48 0.56 0.64 0.80 0.88 1.00 1.20 1.40 1.60 1.80 2.00 2.40 3.20 4.00 4.80 5.60 6.40 7.20 8.00
Max. 2 p c 0.50 0.50 0.60 0.70 0.80 0.90 0.90 1.00 1.20 1.40 1.50 1.60 2.00 2.50 3.00 3.50 4.00 4.00 5.00 5.00
Nom.
Max. 0.45 0.50 0.50 0.60 0.70 0.80 0.80 1.00 1.00 1.20 1.20 1.51 1.91 2.31 2.81 3.31 3.31 4.37 4.37 5.37
Min. 0.31 0.36 0.36 0.46 0.56 0.66 0.66 0.86 0.86 1.06 1.06 1.26 1.66 2.06 2.56 3.06 3.06 4.07 4.07 5.07
Min.
2.0 2.5 2.5 3.0 4.0 4.0 5.0 6.0 6.0 8.0 8.0
M1
2.00 2.40 2.80 3.20 4.00 4.40 5.00 6.00 7.00 8.00 9.00
1.75 2.10 2.45 2.80 3.50 3.85 4.38 5.25 6.10 7.00 7.85 8.75
0.50 0.60 0.70 0.80 1.00 1.10 1.25 1.50 1.75 2.00 2.25 2.50 3.00 4.00 5.00 6.00 7.00 8.00 9.00
0.45 0.54 0.63 0.72 0.90 0.99 1.12 1.35 1.57 1.80 2.03 2.25 2.70 3.60 4.50 5.40 6.30 7.20 8.10 9.00
0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.4 0.4 0.6 0.6 0.6 0.6 0.8
d d d
M1.2
0.30 0.35 0.40 0.50 0.55 0.60 0.75 0.90 1.00 1.10 1.25 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
(M1.4)
M1.6 M2.0
15.0 16.0 17.0 18.0 19.0 20.0 22.0 24.0 25.0 28.0 34.0 40.0 46.0 52.0 58.0 64.0 70.0
(M2.2)
M2.5
M3
(M3.5)
M4
(M4.5)
M5 M6 M8
10.00 12.00 16.00 20.00 24.00 28.00 32.00 36.00 40.00
10.0 12.0 16.0 20.0 25.0 25.0 32.0 32.0 40.0
10.50 14.00 17.50 21.00 24.50 28.00 31.50 35.00
0.25
M10 M12
(M14)
M16
(M18)
M20
10.00
a Nominal sizes shown in parentheses are non-preferred. b See Radius Under the Head of Screws description in text. c See text following table in Lengths of Thread on Screws description in text. d Threaded up to head. All dimensions are given in millimeters. For dimensional notation see diagram on page 1804 . Recessed head screws are also standard and available. For dimensions see British Standard.
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