What are the technical terms for screws?

Screws have several technical terms associated with their various features and aspects. Here are some of the key terms:


  1. Thread Pitch: Measured in threads per inch (TPI) for imperial screws or the distance between threads in millimeters for metric screws.
  2. Thread Profile: The shape of the thread cross-section, such as:
    • V-thread: Common profile for general-purpose screws.
    • Square Thread: Used for high-load applications.
    • Acme Thread: Similar to square threads but easier to machine, used in power screws.
    • Buttress Thread: Designed for applications requiring high strength in one direction.


  1. Partially Threaded Shank: Common in wood screws, where the unthreaded portion provides a clamping force.
  2. Fully Threaded Shank: Common in machine screws, where the thread extends the full length of the screw for maximum holding power.

Head Types

  1. Flat Head: Sits flush with the surface.
  2. Pan Head: Rounded top with a flat bearing surface.
  3. Round Head: Fully rounded top.
  4. Oval Head: Rounded top with a tapered bearing surface.
  5. Truss Head: Wide, slightly rounded head.
  6. Bugle Head: Tapered underside for use in drywall.

Drive Types

  1. Phillips: Cross-shaped, self-centering.
  2. Slotted: Single slot, prone to cam-out.
  3. Torx: Star-shaped, high torque tolerance.
  4. Hex: Hexagonal recess, driven with an Allen wrench.
  5. Robertson: Square recess, common in woodworking.
  6. Pozidriv: Similar to Phillips but with additional contact points for reduced cam-out.
  7. Tri-wing, Torq-set, and Spanner: Specialty drives for tamper resistance.

Point Types

  1. Sharp Point: Standard for wood screws.
  2. Self-drilling Point: Has a drill bit-like tip for drilling its own pilot hole.
  3. Type 17 Point: A notched tip for fast starting in wood.
  4. Blunt Point: Used for machine screws and bolts.

Materials and Coatings

  1. Steel: Standard material, strong and versatile.
  2. Stainless Steel: Corrosion-resistant, used in outdoor or marine environments.
  3. Brass: Corrosion-resistant and non-magnetic, used in electrical applications.
  4. Aluminum: Lightweight and corrosion-resistant, used where weight is a concern.
  5. Titanium: High strength-to-weight ratio, used in aerospace and high-performance applications.


  1. Zinc Plating: Corrosion-resistant, commonly used.
  2. Black Oxide: Provides mild corrosion resistance and a sleek appearance.
  3. Galvanized: Heavy-duty zinc coating for outdoor use.
  4. Phosphate Coating: Provides good paint adhesion and mild corrosion resistance.
  5. Chrome or Nickel Plating: Decorative and corrosion-resistant.

Length and Diameter

  • Length: Measured from the tip to the underside of the head for countersunk screws or from the tip to the top of the head for non-countersunk screws.
  • Diameter (Gauge): Varies depending on the screw type, measured in either a numeric gauge system (e.g., #6, #8, #10) or in fractional inches or millimeters.

Types of Screws

  1. Wood Screws: Designed for wood, with a tapered shank and coarse threads.
  2. Machine Screws: Uniform diameter along the shank, used with nuts or tapped holes.
  3. Sheet Metal Screws: Sharp threads for securing metal sheets.
  4. Lag Screws (Lag Bolts): Large wood screws with hex heads for heavy-duty applications.
  5. Self-tapping Screws: Can tap their own threads in materials like metal and plastic.
  6. Drywall Screws: Designed for attaching drywall to wood or metal studs.
  7. Deck Screws: Coated for outdoor use, typically have a bugle head.
  8. Set Screws: Headless screws used to secure an object within another object, like a shaft in a collar.
  9. Cap Screws: Used in precise applications, with a hex head and fully threaded shank.

Understanding these details helps in selecting the correct screw for specific applications, ensuring the right combination of strength, corrosion resistance, and ease of use.

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