Twist drill bit - has shank grooves at angle which increases progressively towards tip from 15 to 40 degrees

摘要

The twist drill bit consists of a shank (5) and tip (6), with two spiral grooves (1,2) along the sides of the shank for the removal of swarf. The two grooves in the shank are made at an angle which increases towards the tip of the shank, varying progressively from 15 to 40 degrees. ADVANTAGE - Improved drilling of various types of materials.