Screw Points & Thread Styles

Screw Points & Thread Styles

Point/Thread Styles

The point styles on a screw serve the purpose of tapping, cutting or drilling through the desired material. There are five main screw point categories:

  1. Tapping screws – tapping screws get their name because they “tap” their own mating threads.  Some tapping screws require a hole while others are self-drilling. They are identified by a designation of its thread and point:
    1. Type A Point
    2. Type AB Point
    3. Type B Point
    4. Type BP Point
    5. Type 17 Point

  1. Thread cutting screws – thread cutting screws are self-tapping screws that create new threads in existing holes.  Often used in wood and plastic.
    1. Type F Point
    2. Type 1 Point
    3. Type 23 Point
    4. Type 25 Point
    5. Type 17 Point
    6. Type BF Point
    7. Type G Point

  1. Thread forming screws – thread forming screws provide a tighter hold because it mates with zero clearance.
    1. Tri-round Type TT Point
    2. Type C Point
    3. Type CA Point
    4. Type PT Point
    5. Type Hi-Lo Point
    6. Low Root Point
  2. Self-drilling screws – Self-drilling screws eliminate the need for hole preparation
    1. Self-Piercing Point
    2. Self-Drill Point

  1. Machine & Tapping Screws – uniform threads designed to fasten into uniformly threaded nuts or threaded holes
    1. Header Point
    2. Dog Point
    3. Rolled Point
    4. Pinch Point (rounded)
    5. Nail Point (pinched)
    6. Cupped Point
    7. Round Point
    8. Cone Point
    9. Type U Drive Point

High-Low Style
DescriptionA thread forming screw with a double-lead, consisting of a high and low thread. The lower thread varies in height from 1/3 to 1/2 that of the higher thread, which is sharper and flatter than a standard thread.
Applications/
Advantages
For use in plastic, nylon, wood or other low-density materials. Thread design reduces driving torques, enhances resistance to thread stripping, improves pullout strength and lessens risk of cracking the work piece.
Type-A
DescriptionA thread forming tapping screw with wider spaced threads than a Type-AB and a gimlet point.
Applications/
Advantages
For self starting in thin (.015-.050 thick) metal or resin-filled plywood.18-8 Stainless steel tapping screws may be used in applications which require general atmospheric corrosion resistance. Fastening stainless steel parts to aluminum or steel can cause a type of corrosion known as a galvanic couple in some environments.
Type-AB
DescriptionA thread forming tapping screw with spaced threads and a gimlet point.
Applications/
Advantages
For self starting in thin metal or resin-filled plywood. Recommended over a Type-A, particularly in brittle materials.
Type-B
DescriptionA thread forming tapping screw with spaced threads and a blunt point with incomplete entering threads.
Applications/
Advantages
For molded or through holes in thin metal, non-ferrous castings,plastics or resin-filled plywood.

Thread Cutting

Type 25
DescriptionA thread cutting screw with spaced threads, a blunt point, tapered entering threads, a single wide cutting edge, and a chip cavity.
Applications/
Advantages
For molded or through holes in plastics and other soft materials.Provides excellent chip clearing capability.
Type-23
DescriptionA thread cutting screw with machine screw thread pitch, a blunt point,tapered entering threads, a single wide cutting edge, and a chip cavity.
Applications/
Advantages
For cast iron and zinc, aluminum die castings, and plastics. Providesexcellent chip clearing with minimum tightening torques.
Type-1
DescriptionA thread cutting screw with machine screw thread pitch, blunt point,tapered entering threads and a single cutting edge.
Applications/
Advantages
May be used in steel sheets, structural shapes, special alloy steels,
cast iron, brass or plastics.
Type-F
DescriptionA thread cutting screw with machine screw thread pitch, blunt point,tapered entering threads and a single cutting edge.
Applications/
Advantages
For use in heavy gauge sheet metal, aluminum, zinc and lead die castings, cast iron, brass and plastic.

Floorboard Screws

Type-F
DescriptionA countersunk, torx® drive thread cutting screw with machine screw thread pitch, blunt point, tapered entering threads, and multiple cuttingedges.Floorboard screws are, by definition, available in much longersizes than standard type-F screws.
Applications/
Advantages
Floorboard screws are specifically designed for installing wood floors into truck trailers.

Floorboard Screws

Type-BSD and Type-CSD
DescriptionType BSD: A tapping screw with spaced threads and a drill point which drills its own hole. Type CSD: A wafer head thread forming screw with machine screw thread pitch and a drill point which drills its own hole.Both types allow the screw to form mating threads and produce a complete fastening system in a single operation.
Applications/
Advantages
Type BSD: May be used to attach plywood, soft woods or composition board to metal, or attach metal to metal. Type CSD: The finer thread pitch reduces friction and driving torques. Type-CSD screws arenormally used with thicker materials. The wafer head design allows thescrew to set flush in wood and softer materials and provides a clean,finished appearance. All self-drilling screws offer economical benefits:reduces labor and tooling costs; reduces or eliminates drill bits and taps.
Reamer with Wings
DescriptionReamer with Wings: A Type CSD self-drilling screw with reaming wings located at opposite sides of the shank, below the threads and above the drill point.
Applications/
Advantages
May be used for drilling through wood over 1/2" thick and the metal surface behind it. The wings drill out a clearance hole in wood or other soft materials, then snap off when in contact with the metal surface to be drilled.

Self-Piercing

Slotted Hex Washer
DescriptionA slotted hex washer head thread forming tapping screw with a single lead thread rolled to the tip of an extra sharp point, and a second thread spaced 180° apart.
Applications/
Advantages
May be used in thin metal (less than .050 thick). Eliminates need for pre-drilled or pre-punched holes.Undercut area beneath the head allows greater length of thread engagement. Twin lead threads help to reduce driving torque.
Coarse Thread Drywall, Deck & Particle Board Screws
DescriptionCoarse thread Drywall–Sharp point: A bugle head screw with spaced threads, extra sharp point and black phosphate finish. Particle Board Screw: Same as a coarse thread drywall screw but available in shorter lengths than standard drywall screws. Deck Screw: A bugle head screw with spaced threads,extra sharp point and dacrotized finish.
Applications/
Advantages
Coarse thread Drywall–Sharp point: For attaching drywall to wood studs or to 25 gage metal studs.Particle Board Screw: Designed specifically for use in dense woods, especially man-made types such as chipboard and particle board. Deck Screw: Designed specifically for joining pieces of pressure treated lumber. Provides superior corrosion resistance without discoloring the wood.

Fine Thread Drywall Screws

Drill point Drywall & Sharp point Drywall
DescriptionFine thread Drywall–Sharp point: A bugle head screw with twinfast thread, extra sharp point and black phosphate finish. Fine thread Drywall–Drill point: A bugle head screw with twin lead spaced thread, self drilling point and black phosphate finish.
Applications/
Advantages
Fine thread Drywall–Sharp point: For attaching drywall to metal studs from 25 gage through 20 gage thick. Longer sizes are ideal for multiple layers or insulation. Fine thread Drywall–Drill point: Will drive easily through drywall, drill a hole in a steel stud up to 14 gage thick, and form its own mating thread.Can also be used for attaching plywood or insulation board to 14 gage metal.

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