This type of recess has a large center opening, wide straight wings, and blunt bottom, with all edges relieved or rounded.

Applicable to screw types as indicated by code symbols.
  • Types B and BP thread forming and Types BF and BT thread cutting.
  • Type C thread forming and Types D, F, G, and T thread cutting.
Unit of Measure

Manufacturer

Manufacturer

N/A Industrial Fasteners Institute

Specifications

Product

N/A Tapping Screws

Unit of Measure

N/A English

Type

N/A Type IA Short Screws

Nominal Size or Basic Screw Dia.

N/A 3/8 in

Nominal Size or Basic Screw Dia. (Decimal)

N/A 0.3750 in

Head Size

N/A 5/16 in
Applicable to Screw Types1 N/A 3
4

Ref. Recess Dia. (M)

N/A 0.384 in

Ref. Recess Depth ((T)

N/A 0.232 in

Ref. Recess Width (N)

N/A 0.086 in

Driver Size

N/A 4

Max. Recess Penetration Gaging Depth

N/A 0.215 in

Min. Recess Penetration Gaging Depth

N/A 0.197 in

Max. Protrusion Above Gaging Dia. (F)

N/A 0.155 in

Min. Protrusion Above Gaging Dia. (F)

N/A 0.117 in

Gaging Dia. (G)

N/A 0.539 in

Codes and Standards

Codes and Standards

N/A Abstract of ASME B18.6.4 1998
  • 1 1 = Circle, 2 = Diamond, 3 = Triangle, 4 = Square
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