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Countersink vs. Counterbore

Countersink

A countersink is a cone shaped hole cut into the laminate. It is typically used to allow the tapered head of a screw to sit flush with the top of the laminate. By comparison, a counterbore makes a flat-bottomed hole and its sides are drilled straight down. This is usually used to fit a hex-headed cap or screw.

To accurately drill your countersunk holes, we will need the following information.

  1. Angle of the drill
  2. Major Diameter (finished diameter of the hole at the surface)
  3. Depth the countersink is to be drilled
  4. On which side of the board is the sink? Top or Bottom?
  5. The finished diameter of the shaft of the hole
  6. Is the sink and shaft to be plated or non-plated?

Countersink Anatomy.png

Countersink examples at different angles.
Countersinks of different angles.png

Counterbore

A counterbored hole is typically used when a fastener such as a bolt or cap head screw is required to sit flush with or below the level of a surface.

To fabricate your counterbored holes, we need to know the following information.

  1. Major Diameter (finished diameter of the hole at the surface)
  2. Depth the countersink is to be drilled
  3. On which side of the board is the sink? Top or Bottom?
  4. The finished diameter of the shaft of the hole
  5. Is the bore and shaft to be plated or non-plated?

Because the sides of the hole are always parallel, there is no need to specify an angle.

Counterbore Anatomy.png

Counterbore example.PNG