Drill Diameter
The values indicated in the relevant dimensional standards apply in respect of the diameter of Twist Drills
Test Point : on the leads at the corners（see Fig.1 )
Test equipment: micrometer
Tapering of Diameter
The diameter of twist drills usually reduces from the drill tip towards the shank in the area of the flute
Test values : the taper on diameter amoutns to 0.02 to 0.08mm over a length of 100mm
Test point: at the outside diameter on the land
Test equipment : micrometer and indicating measuring instruments
Point Angle
Test value : 118° or 135°
Test point : at the cutting edges ( see Fig.2)
Test equipment: Univeral bevel protractor indicating measuring instruments
