Countersink

A cross-hole, "Weldon style" or "zero flute" countersink is a cone-shaped tool with a cutting edge provided by a hole that goes through the side of the cone.

The fluted countersink cutter is used to provide a heavy chamfer in the entrance to a drilled hole.

This may be required to allow the correct seating for a countersunk-head screw or to provide the lead in for a second machining operation such as tapping.

This variation in pitching reduces the chance of the cutting edges setting up a harmonic action and leaving an undulated surface.

With a variable-speed handheld power drill, the trigger is best squeezed lightly to yield a low spindle speed.

Good chatter-free results can usually be had by countersinking by hand (as opposed to running the tool in a powered spindle).

With a quarter-inch-hex shank, the countersink cutter can be held with a screwdriver handle of the indexable-bit type.

This style of construction is often seen in modern household appliance design, because it allows the product to be lower-priced, and the quality can still be good as long as the sheet is thick enough.