Making hole

Marking witness marks

Locating centre of the hole

Marking light punch marks for divider point

Marking is accurate

Marking is inaccurate

Surface finish will decrease

Surface finish will increase

Excessive vibration

Get better surface

Less metal removed

More metal removed

Chisel will slip

cutting edge break

Proper cutting take place

Cutting edge digs in the work

Good cutting

Less cutting

Chisel will slip

Cutting edge dig in the work