Type AB Screw Thread
Specifications and Dimensions



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

Basic Screw Diameter
or Nominal Size
Threads
Per Inch
D d L Minimum
Torsional
Strength
(Lb In)
Major Diameter Minor Diameter Minimum Practical
Screw Length
Max Min Max Min 90° Heads Csk Heads
2 .560 32 .088 .082 .064 .060 3/16 7/32 4
4 .1120 24 .114 .108 .086 .082 7/32 9/32 13
5 .1250 20 .130 .123 .094 .090 1/4 5/16 18
6 .1380 20 .139 .132 .104 .099 9/32 11/32 24
7 .1510 19 .154 .147 .115 .109 5/16 3/8 30
8 .1640 18 .166 .159 .122 .116 5/16 3/8 39
10 .1900 16 .189 .182 .141 .135 3/8 7/16 56
12 .2160 14 .215 .208 .164 .157 7/16 21/32 88
1/4 .2500 14 .246 .237 .192 .185 1/2 19/32 142
5/16 .3125 12 .315 .306 .244 .236 5/8 3/4 290
3/8 .3750 12 .380 .371 .309 .299 3/4 29/32 590
* Countersunk Bolts and Screws lengths are always measured from the top of the head

  • Advantages For self starting in thin, .015-.050, metal or resin filled plywood. Recommended over a Type A, particularly in brittle materials.
  • Material AISI 1016-1024 oe equivalent steel8
  • Heat Treatment Steel only - Quenched in liquid and then tempered by reheating to 650°F minimum
  • Case 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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Phone: ( 323 ) 587-0382 • FAX: ( 323 ) 587-8712 • E-mail: [email protected]
Copyright © 2009 by Smith Fastener Company

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