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Countersinking Guidelines

Countersinking is a method of creating a conical hole in a sheet metal piece, allowing for the flush attachment of fasteners like screws or bolts.


Larger countersinks in thinner materials will enlarge the inner hole diameter. This can cause issues with your part fitment. Please make sure to account for this when designing your parts.

Countersinking is a vital process in sheet metal fabrication, particularly when creating components that require a smooth surface with no protruding screw heads or fasteners. This technique involves enlarging the top portion of a pre-drilled hole, creating a tapered seat that allows flat-head screws or bolts to sit flush with or beneath the surface of the sheet metal.

NameUnitsHole SizeOuter Diameter