Machinery's Handbook, 31st Edition
1852 Metric Self-Threading Screws Table 4. ANSI Standard Thread and Point Dimensions for Types BF, BT, D, F, and T Metric Thread Cutting Tapping Screws ANSI/ASME B18.6.5M-2000 (Withdrawn) Types BF and BT
D 1
D 2
D 3
Y
L
Point Taper Length Type B b
Minimal Practical Nominal Screw Length c
Basic Screw Diame ter
Nominal Screw Size and Thread Pitch
Basic Thread Pitch
Thread Major Diameter
Thread Minor Diameter
Point Diameter a
Pan, Hex and Hex Flange Heads
Flat and Oval Countersunk Heads
Ref. d
Ref. d
Max. Min. Max. Min. Max. Min. Max. Min.
2.184 0.79 2.24 2.10 1.63 1.52 1.47 1.37 1.6 1.2 2.845 1.06 2.90 2.76 2.18 2.08 2.01 1.88 2.1 1.6 3.505 1.27 3.53 3.35 2.64 2.51 2.41 2.26 2.5 1.9 4.166 1.41 4.22 4.04 3.10 2.95 2.84 2.69 2.8 2.1 4.826 1.59 4.80 4.62 3.58 3.43 3.30 3.12 3.2 2.4 5.486 1.81 5.46 5.28 4.17 3.99 3.86 3.68 3.6 2.7 6.350 1.81 6.25 6.03 4.88 4.70 4.55 4.34 3.6 2.7 7.938 2.12 8.00 7.78 6.20 5.99 5.84 5.64 4.2 3.2 9.525 2.12 9.65 9.43 7.85 7.59 7.44 7.24 4.2 3.2
4 5 6 7 8 9
5 7 8
2.2 × 0.8 2.9 × 1 3.5 × 1.3 4.2 × 1.4 4.8 × 1.6 5.5 × 1.8 6.3 × 1.8 8 × 2.1 9.5 × 2.1
10 11 12 13 17 19
10 12 14
a The tabulated values apply to screw blanks prior to roll threading. b The tabulated maximum limits are equal to approximately two times the thread pitch. c Lengths shown are theoretical minimums and are intended to assist in the selection of appropriate short screw lengths. See Table 2 for recommended length-diameter combinations. For Types D, F, and T, shorter screws are available with the point length reduced to the limits tabulated for short screws. d Basic screw diameter and basic thread pitch are used for calculation purposes whenever these factors appear in formulations for dimensions. Types D, F, T D 1 D 3 D S Y L Nominal Screw Size and Thread Pitch Thread Major Diameter Point Diameter a Body Diameter a Point Taper Length Minimum Practical Nominal Screw Length c For Short Screws For Long Screws b Pan, Hex and Hex Flange Heads Flat and Oval Countersunk Heads
Max. Min. Max. Min. 2.00 1.88 1.45 1.39 2.50 2.37 1.88 1.82 3.00 2.87 2.32 2.26 3.50 3.35 2.68 2.60 4.00 3.83 3.07 2.97 5.00 4.82 3.94 3.84 6.00 5.79 4.69 4.55 8.00 7.76 6.40 6.24 10.00 9.73 8.08 7.88
Min. 1.65 2.12 2.58 3.00 3.43 4.36 5.21 7.04 8.86
Max. Min. Max. Min. 1.4 1.0 1.8 1.4 1.6 1.1 2.0 1.6 1.8 1.3 2.3 1.8 2.1 1.5 2.7 2.1 2.5 1.8 3.2 2.5 2.8 2.0 3.6 2.8 3.5 2.5 4.5 3.5 4.4 3.1 5.6 4.4 5.3 3.8 6.8 5.3
4 4 5 5 6 7 9
5 6 6 8 9
2 × 0.4
2.5 × 0.45 3 × 0.5 3.5 × 0.6 4 × 0.7 5 × 0.8
10 12 16
6 × 1
11 13
8 × 1.25 10 × 1.5
18 a Minimum limits for body diameter (unthreaded portion) are tabulated for convenient reference. For Types BF and BT, the body diameter is not less than the minimum minor diameter nor greater than the maximum major diameter of the thread. b Long screws are screws of nominal lengths equal to or longer than those listed under L. All dimensions are in millimeters. See Table 1 for thread diagrams. Material and Heat Treatment.— Tapping screws are normally fabricated from carbon steel and are suitably processed to meet the performance and test requirements outlined in the standard, B18.6.5M. Tapping screws may also be made from corrosion resistant steel, Monel, brass, and aluminum alloys. The materials, properties, and performance characteristics applicable to such screws should be mutually agreed upon between the manufacturer and the purchaser.
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