Engineering Tutorials

Counter sinking: Counter sinking is the operation of making a cone shaped enlargement at the end of a hole to provide recess for a flat head screw or a countersunk rivet. The counter-sunks (tools used for counter sinking) carry included angles of 60°, 82° or 90° and the cutting edges of the tool are formed at the conical surface.

Counter boring: Counter boring is the operation of enlarging one end of an existing hole concentric with the original hole with square bottom. It is done to accommodate the heads of bolts, studs and pins. The cutting edges of the counter-bore (tool used for counter boring) may have straight or spiral teeth.