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Type BF and BT, Thread Cutting Tapping Screws [Table 7]

ASME B 18.6.4 (BF/BT) - 1998 (R2005)

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美标ASME B18.6.4 (BF/BT) - 1998 (R2005) AS Type BF and BT, Thread Cutting Tapping Screws  [Table 7]
Nominal Diameter
0# 1# 2# 3# 4# 5# 6# 7#
Nominal Diameter
PP
d max
min
d1 max
min
dp Ref.
s max
min
L min 90° Heads
Csk. Heads
0.0600 0.0730 0.0860 0.0990 0.1120 0.1250 0.1380 0.1510
48 42 32 28 24 20 20 19
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
Nominal Diameter
8# 10# 12# 1/4 5/16 3/8 7/16 1/2
Nominal Diameter
PP
d max
min
d1 max
min
dp Ref.
s max
min
L min 90° Heads
Csk. Heads
0.1640 0.1900 0.2160 0.2500 0.3125 0.3750 0.4375 0.5000
18 16 14 14 12 12 10 10
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,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 larger sizes.
②,Points 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° to 95° and the thread cutting edge located above the axis of screw. 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 complete at manufacturer’s option and flutes may be one pitch short of first full form thread. Other details of taper and flute design shall be optional with manufacturer provided the screws meet the specified performance requirements.

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