Type B Screw Thread
Specifications and Dimensions



Thread Dimensions for Type B Self-tapping Screw Threads
ANSI B18.6.4

Basic Screw Diameter
or
Nominal Size
Threads
Per Inch
D d P S L Minimum
Torsional
Strength
(Lb In)
(Steel
Screws
Only)
Major Diameter Minor Diameter Point Diameter Point Taper
Length
Minimum
Practical
Screw Length
Max Min Max Min Max Min Max Min 90° Heads Csk Heads
2 .0860 32 .088 .082 .064 .060 .058 .054 .062 .047 5/32 3/16 4
3 .0990 28 .101 .095 .075 .071 .068 .064 .071 .054 3/16 7/32 9
4 .1120 24 .114 .108 .086 .082 .079 .074 .083 .063 3/16 1/4 13
5 .1250 20 .130 .123 .094 .090 .087 .082 .100 .075 7/32 9/32 18
6 .1380 20 .139 .132 .104 .099 .095 .089 .100 .075 1/4 9/32 24
7 .1510 19 .154 .147 .115 .109 .105 .099 .105 .079 1/4 5/16 30
8 .1640 18 .166 .159 .122 .116 .112 .106 .111 .083 9/32 11/32 39
10 .1900 16 .189 .182 .141 .135 .130 .123 .125 .094 5/16 3/8 56
12 .2160 14 .215 .208 .164 .157 .152 .145 .143 .107 11/32 7/16 88
1/4 .2500 14 .246 .237 .192 .185 .179 .171 .143 .107 3/8 1/2 142
5/16 .3125 12 .315 .306 .244 .236 .230 .222 .167 .125 15/32 19/32 290
3/8 .3750 12 .380 .371 .309 .299 .293 .285 .167 .125 17/32 11/16 590
Length Tolerance: Up to/including 3/4" = -.03, Over 3/4 to/including 1-1/2" = -.05, Over 1-1/2" = -.06
* Countersunk Bolts and Screws lengths are always measured from the top of the head

  • Applications For molded or through holes in thin metal, non ferrous castings, plastics or resin filled plywood.
  • Material Steel: AISI 1016-1024 oe equivalent steel
  • Heat Treatment Quenched in liquid and then tempered by reheating to 650°F minimum
  • Surface Hardness Rockwell C45 Minimum
  • Case Depth Nos. 4 thru 6 Dia. - .002-.007, Nos. 8 thru 12 dia. - .004 - .009, 1/4" and larger - .005 - .011
  • Core Hardness Rockwell C28 - C38 after tempering
  • Plating See plating pages




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