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Module one: History and Safety
Module four: Specialist Electricians Tools
Module three: Core Electricians Tools
Module three: Core Electricians Tools
Power Tool Accessories.
Drill Terminology
Swarf (turnings or chippings)
Swarf is the metal chippings resulting from drilling or cutting metal.
Wandering
Have you ever tried to drill a hole and the drill bits sets off across the wall, leaving a snail trail – that’s wandering.
Chatter
Can you drill a non round hole – the answer is yes. If the drill has been incorrectly ground, the drill will chatter in the hole causing some very peculiar shapes.
The rate of twist of the flutes will be optimized for the drills intended use, but ultimately it comes down to how much swarf or debris needs to be ejected for effective drilling.
Flutes (spiral)
The flutes are there to eject the swarf or debris from the hole and stop the drill from clogging and jamming.
Cutting edge
The geometry and sharpening of the cutting edges is crucial to the performance of the bit. This geometry is controlled by the point angle and the lip angle – see below.
The C.K HSS drill bits cutting edge geometry has a split point angle of 135 degrees. This makes the drill bit suitable for harder materials like steel.
Point angle
The point angle is optimized for the material the drill bit is intended to go through.
As a rule harder materials require a more blunt point angle, and softer materials require a sharper angle.
The C.K HSS drill bits feature splint point tips have a cross point which makes the drilling easier to start as the drill bits are self-centring.
Having the correct point angle for the hardness of the material controls wandering, chatter, hole shape and wear rate.
Lip angle
The lip angle determines how much supporting material is behind the cutting edge.
Having a sharp angle will make the drill cut more aggressively under the same amount of point pressure as a drill with a blunter lip angle.