Used for hard material

Used for high carbon steel

Used for soft and tough material

Used for normal low carbon steel

Unequal point thinning

Drill point not in centre

Clearance angle is incorrect

Drill cutting edges are not sharp

18.75 mm

19.00 mm

19.25 mm

19.05 mm

Drill is not sharp

Feed rate is too high

Cutting speed is too high

Unequal angle of cutting edge

Root

Crest

Flank

Pitch