Screw Head Shapes
- Pan head
- A low disc with chamfered outer edge
- Button or dome head
- Cylindrical with a rounded top
- Round head
- A dome-shaped head used for decoration.
- Mushroom or Truss head
- Lower-profile dome designed to prevent tampering
- Countersunk or flat head
- Conical, with flat outer face and tapering inner face allowing it to sink into the material. The angle of the screw is measured as the full angle of the cone.
- Oval or raised head
- A decorative screw head with a countersunk bottom and rounded top. Also known as "raised countersunk" (UK)
- Bugle head
- Similar to countersunk, but there is a smooth progression from the shank to the angle of the head, similar to the bell of a bugle
- Cheese head
- Disc with cylindrical outer edge, height approximately half the head diameter
- Fillister head
- Cylindrical, but with a slightly convex top surface. Height to diameter ratio is larger than cheese head.
- Flanged head
- A flanged head can be any of the above head styles (except the countersunk styles) with the addition of an integrated flange at the base of the head. This eliminates the need for a flat washer.
Some varieties of screw are manufactured with a break-away head, which snaps off when adequate torque is applied. This prevents tampering and also provides an easily inspectable joint to guarantee proper assembly. An example of this is the shear bolts used on vehicle steering columns, to secure the ignition switch.
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