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Unit:inch

Dimensions of Threads and Points for Types BF and BT Thread-Cutting Tapping Screws

ASME/ANSI B 18.6.3 (T43) - 2013

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美标ASME/ANSI B18.6.3 (T43) - 2013 ASME/AN Dimensions of Threads and Points for Types BF and BT Thread-Cutting Tapping Screws
Screw Thread
d
0# 1# 2# 3# 4# 5# 6# 7#
PP Threads per in.
D Nominal Diameter
max
min
d max
min
P Ref.
S Point Taper Length /max
Point Taper Length /min
L 90-deg Heads /min
CsK. Heads /min
48 42 32 28 24 20 20 19
0.0600 0.0730 0.0860 0.0990 0.1120 0.1250 0.1380 0.1510
0.060 0.075 0.088 0.101 0.114 0.130 0.139 0.154
0.054 0.069 0.082 0.095 0.108 0.123 0.132 0.147
0.036 0.049 0.064 0.075 0.086 0.094 0.104 0.115
0.033 0.046 0.060 0.071 0.082 0.090 0.099 0.109
0.031 0.044 0.058 0.068 0.079 0.087 0.095 0.105
0.042 0.048 0.062 0.071 0.083 0.100 0.100 0.105
0.031 0.036 0.047 0.054 0.063 0.075 0.075 0.079
1/8 1/8 5/32 3/16 3/16 7/32 1/4 1/4
1/8 5/32 3/16 7/32 1/4 9/32 9/32 5/16
Screw Thread
d
8# 10# 12# 1/4 5/16 3/8 7/16 1/2
PP Threads per in.
D Nominal Diameter
max
min
d max
min
P Ref.
S Point Taper Length /max
Point Taper Length /min
L 90-deg Heads /min
CsK. Heads /min
18 16 14 14 12 12 10 10
0.1640 0.1900 0.2160 0.2500 0.3125 0.3750 0.4375 0.5000
0.166 0.189 0.215 0.246 0.315 0.380 0.440 0.504
0.159 0.182 0.208 0.237 0.306 0.371 0.429 0.493
0.122 0.141 0.164 0.192 0.244 0.309 0.359 0.423
0.116 0.135 0.157 0.185 0.236 0.299 0.349 0.413
0.112 0.130 0.152 0.179 0.230 0.293 0.343 0.407
0.111 0.125 0.143 0.143 0.167 0.167 0.200 0.200
0.083 0.094 0.107 0.107 0.125 0.125 0.150 0.150
9/32 5/16 11/32 3/8 15/32 17/32 5/8 11/16
11/32 3/8 7/16 1/2 19/32 11/16 25/32 27/32
①,Point of screws shall be tapered and fluted or slotted as illustrated above for the respective types. The flute on Type BT screws shall have an included angle of 90 deg to 95 deg and the thread cutting edge located above the axis of screws. Tapered threads shall have unfinished crests, and the flutes or slots shall extend through first full form thread beyond taper except for Type BF screws on which tapered threads may be comlete at manufacturer's option and flutes may be one pitch short of first full form thread. Other details of taper and flutes design shall be optional with the manufacturer provided the screws meet the specified performance requirements.
②,The width of flat at crest of thread shall not exceed 0.004 in. for sizes up to and including No.8, and 0.006 in. for large sizes.

Alternative history

ASME/ANSI B 18.6.3 - 2010 ASME/ANSI B 18.6.3 - 2010 ASME/ANSI B 18.6.3T43 - 2013 ASME B 18.6.3T4.1.2.1-1 - 2024
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