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  • 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 90º to 95º 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 screw son 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.
  • 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.
  • Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
Unit of Measure

Manufacturer

Manufacturer

N/A Industrial Fasteners Institute

Specifications

Product

N/A Tapping Screws

Unit of Measure

N/A English

Nominal Size or Basic Screw Dia.

N/A No. 3

Nominal Size or Basic Screw Dia. (Decimal)

N/A 0.0990 in

Max. Major Dia. (D)

N/A 0.101 in

Min. Major Dia. (D)

N/A 0.095 in

Max. Minor Dia. (d)

N/A 0.075 in

Min. Minor Dia. (d)

N/A 0.071 in

Ref. Point Dia. (P)

N/A 0.068 in

Max. Point Taper Length (S)

N/A 0.071 in

Min. Point Taper Length (S)

N/A 0.054 in

Min. Practical Nominal Screw Lengths for 90º Heads (L)

N/A 3/16 in

Min. Practical Nominal Screw Lengths for Csk Heads (L)

N/A 7/32 in

Codes and Standards

Codes and Standards

N/A ASME B18.6.4 1998

Threads Per Inch

Threads Per Inch

N/A 28