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Tapping Screws
tapping-screws
Slotted Flat Countersunk Head Tapping Screws
(21)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Type C thread forming; and Types D, F, G, and T thread cutting. - Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of these lengths and shorter shall have undercut heads. Use Type AB undercut head screws in place of Type A screws for these lengths and shorter.
- Tabulated values determined from formula for H max, Appendix.
- No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas shown in Appendix.
Cross Recessed Flat Countersunk Head Tapping Screws
(63)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Head dimensions not shown are the same as those of slotted heads
- Not practical to gage sizes No. 0 and No. 1.
Slotted Undercut Flat Countersunk Head Tapping Screws
(16)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Type C thread forming; and Types D, F, G, and T thread cutting. - Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of longer lengths shall have head heights.
- No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas shown in Appendix.
Cross Recessed Undercut Flat Countersunk Head Tapping Screws
(48)- When specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Head dimensions not shown are the same as those of slotted heads.
- Not practical to gage sizes No. 0 and No. 1.
Cross Recessed Flat Countersunk Trim Head Tapping Screws
(16)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Type A thread forming, except for short lengths.
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. - Short screws are those threaded full length.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Maximum diameter shall not exceed minimum plus 0.011" for Type A screws, and basic screw diameter for all other screw types.
- Tabulated values determined from formula for H max, Appendix.
- No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas shown in Appendix.
Cross Recess Dimensions for Flat Countersunk Trim Head Tapping Screws
(48) Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted. /Asset/a1119.jpg Slotted Oval Countersunk Head Tapping Screws
(21)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Type A thread forming, except for short lengths.
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. - Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of these lengths and shorter shall have undercut heads. Use Type AB undercut head screws in place of Type A screws for these lengths and shorter.
- Tabulated values determined from formula for H max, Appendix.
- Tabulated values determined from formula for O max, Appendix.
- No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas shown in Appendix.
Cross Recessed Oval Countersunk Head Tapping Screws
(63)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Type A thread forming, except for short lengths.
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. - Head dimensions not shown are the same as those of slotted heads.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
Slotted Undercut Oval Countersunk Head Tapping Screws
(16)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Longer lengths shall have head heights
- Tabulated values determined from formula for H max, Appendix.
- No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas shown in Appendix.
Cross Recessed Undercut Oval Countersunk Head Tapping Screws
(48)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - Head dimensions not shown are the same as those of slotted heads.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
Heads of Oval Countersunk Trim Head Tapping Screws
(16)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - Short screws are those threaded full length.
- Maximum diameter shall not exceed minimum plus 0.11" for Type A screws, and basic screw diameter for all other screw types.
- Tabulated values for H and O determined from formula.
Type I Cross Recessed Oval Countersunk Trim Head Tapping Screws
(32)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas.
- Short screws are those threaded full length.
Type IA Cross Recessed Oval Countersunk Trim Head Tapping Screws
(32)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas.
- Short screws are those threaded full length.
Type II Cross Recessed Oval Countersunk Trim Head Tapping Screws
(16)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protrusion values must be recalculated using the formulas shown in Appendix.
Slotted Pan Head Tapping Screws
(21)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
Cross Recessed Pan Head Tapping Screws
(63)- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Not practical to gage sizes No. 0 and No. 1.
- Head dimensions not shown are the same as those of slotted heads.
Slotted Fillister Head Tapping Screws
(17)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - A slight rounding of the edges at periphery of head shall be permissible, provided the diameter of the bearing circle is equal to no less than 90% of the specified minimum head diameter. For head dimension formulas.
Cross Recessed Fillister Head Tapping Screws
(51)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - A slight rounding of the edges at periphery of head shall be permissible, provided the diameter of the bearing circle is equal to no less than 90% of the specified minimum head diameter.
- Head dimensions not shown are the same as slotted heads.
- Screw sizes No. 0 and No 1 are impractical to gage.
Regular Hex Head Tapping Screws
(18)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - A slight rounding of all edges and corners of the hex surfaces of indented hex heads shall be permissible, provided the diameter of the bearing circle is equal to no less than 90% of the specified minimum width across flats dimension.
- Unless otherwise specified by purchaser, regular hex heads shall be furnished, and both regular and large head styles may be of indented head, trimmed head, or fully upset head construction, at the option of manufacturer.
- Dimensions across flats and across corners of the head shall be measured at the point of maximum metal. Taper of sides of hex (angle between one side and the axis) shall not exceed 2° or 0.004", whichever is greater, the specified width across flats being the large dimension.
- The rounding due to lack of fill on all six corners of the head shall be reasonably uniform and the width across corners of the head shall be such that when a sharp ring having an inside diameter equal to the specified minimum width across corners is placed on the top and bottom of the head, the head shall protrude by an amount equal to, or greater than, the F value tabulated. See Appendix II for across corners gaging of hex heads.
- Large hex head is intended for screw and washer assemblies - SEMS, as specified in ASME B18.1 and other applications requiring large bearing.
Large Hex Head Tapping Screws
(18)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - A slight rounding of all edges and corners of the hex surfaces of indented hex heads shall be permissible, provided the diameter of the bearing circle is equal to no less than 90% of the specified minimum width across flats dimension.
- Unless otherwise specified by purchaser, regular hex heads shall be furnished, and both regular and large head styles may be of indented head, trimmed head, or fully upset head construction, at the option of manufacturer.
- Dimensions across flats and across corners of the head shall be measured at the point of maximum metal. Taper of sides of hex (angle between one side and the axis) shall not exceed 2° or 0.004", whichever is greater, the specified width across flats being the large dimension.
- The rounding due to lack of fill on all six corners of the head shall be reasonably uniform and the width across corners of the head shall be such that when a sharp ring having an inside diameter equal to the specified minimum width across corners is placed on the top and bottom of the head, the head shall protrude by an amount equal to, or greater than, the F value tabulated. See Appendix II for across corners gaging of hex heads.
- Large hex head is intended for screw and washer assemblies - SEMS, as specified in ASME B18.1 and other applications requiring large bearing.
Hex Washer Head Tapping Screws
(17)- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Applicable to screw types as indicated by code symbols.
Type AB thread forming.
Types B and BP thread forming and Types BF and BT thread cutting.
Type C thread forming, Appendix; and Types D, F, G, and T thread cutting. - A slight rounding of all edges and corners of the hex surfaces of heads shall be permissible.
- Fillet radius R at junction of sides of hex and top of washer shall not exceed 0.15 times the basic screw diameter.
- Dimensions across flats and across corners of the head shall be measured at the point of maximum metal. Taper of sides of hex (angle between one side and the axis) shall not exceed 2º or 0.004 in., whichever is greater, the specified width across flats being the large dimension.
- The rounding due to lack of fill on all six corners of the head shall be reasonably uniform and the width across corners of the head shall be such that when a sharp ring having an inside diameter equal to the specified minimum width across corners is placed on the top of the head, the hex portion of the head shall protrude by an amount equal to, or greater than, the F value tabulated.
Thread Forming Tapping Screws Type AB
(16)- No extrusion of excess metal beyond apex of the point resulting from thread rolling shall be permissible. A slight rounding or truncation of the point is desirable.
- 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.
- Sizes shown in boldface type are preferred.
- For determining the effective grip length of Type AB screws.
Thread Forming Tapping Screws Type B
(16)- Threads within point taper length shall have unfinished crests.
- 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.
- For determining the effective grip length of BP screws.
Thread Forming Tapping Screws Type BP
(16)- Threads within point taper length shall have unfinished crests.
- 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.
- For determining the effective grip length of BP screws.
Thread Cutting Tapping Screws Type BF
(16)- 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.
Thread Cutting Tapping Screws Type BT
(16)- 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.
Thread Cutting Tapping Screws Type D
(26)- Points of screws shall be tapered and fluted or slotted as illustrated above for the respective types. The flute on Type T 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 the first full thread beyond taper except for Type F screws on which tapered threads may be complete at manufacturer's option and flutes may be one pitch short of the first full form thread. Other details of taper and flute design shall be optional with the manufacturer, provided the screws meet the specified performance requirements.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of these nominal lengths and shorter shall have point taper lengths specified for short screws. Longer lengths shall have point taper lengths specified for long screws.
Thread Cutting Tapping Screws Type F
(26)- Points of screws shall be tapered and fluted or slotted as illustrated above for the respective types. The flute on Type T 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 the first full thread beyond taper except for Type F screws on which tapered threads may be complete at manufacturer's option and flutes may be one pitch short of the first full form thread. Other details of taper and flute design shall be optional with the manufacturer, provided the screws meet the specified performance requirements.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of these nominal lengths and shorter shall have point taper lengths specified for short screws. Longer lengths shall have point taper lengths specified for long screws.
Thread Cutting Tapping Screws Type G
(26)- Points of screws shall be tapered and fluted or slotted as illustrated above for the respective types. The flute on Type T 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 the first full thread beyond taper except for Type F screws on which tapered threads may be complete at manufacturer's option and flutes may be one pitch short of the first full form thread. Other details of taper and flute design shall be optional with the manufacturer, provided the screws meet the specified performance requirements.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of these nominal lengths and shorter shall have point taper lengths specified for short screws. Longer lengths shall have point taper lengths specified for long screws.
Thread Cutting Tapping Screws Type T
(26)- Points of screws shall be tapered and fluted or slotted as illustrated above for the respective types. The flute on Type T 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 the first full thread beyond taper except for Type F screws on which tapered threads may be complete at manufacturer's option and flutes may be one pitch short of the first full form thread. Other details of taper and flute design shall be optional with the manufacturer, provided the screws meet the specified performance requirements.
- Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.
- Screws of these nominal lengths and shorter shall have point taper lengths specified for short screws. Longer lengths shall have point taper lengths specified for long screws.
