Pipe centre
Female centre
Centre punch
Driving plate
high carbon steel
cast iron
miId steel
bronze
60 degree
108 degree
118 degree
135 degree
For general purpose use point angle of twist drill is 118 Degree.
reaming
counter boring
spot facing
knurling
The process of enlarging the end of a hole to an even depth for housing the socket screw head is called as counter boring.
Cooling and flushing chips away from the cutting tool
Lubrication and better surface finish
Lubrication and facilitation of chip removal
For larger cutting