Type "R" Counterbore - 2 Flute
The Type "R" counterbore is designed to cut clean holes in wood and plastic and can also be used with a Stop Collar if useful to provide an exact bore depth. Stop Collars are also available and sold separately - SKU# 91002767.
Counterbores will cleanly cut the flat under the heads of nails, spikes, and bolts in order to sink them far enough beneath the surface and allow for a wood plug to be used to cover the head.
This two-flute Type "R" counterbore is made of stainless steel. It can be set at any point on a twist drill and held fast with two hex-socket set screws - see photo. The extension lip pattern cutting edges allow it to cut clean holes through wood and plastic without tearing.