4.0 DRILL
4.1 Understand the drill bit and drilling machine (twist drill).
4.1.1 Explain and name the parts of a drill bit (twist drill).
4.1.2 Explain drill sizes are stated and determined.
4.1.3 Explain the steps of marking out before drilling.
4.1.4 Explain the method of holding a drill bit .
4.1.5 Differentiate the various types of drill bits such as centre drill, straight slot drill, blind hole drill and flat tipped drill.
4.1.6 Explain the effects to a drilled hole if the angle of the drill bit tip is not accurate.
4.1.7 Calculate the spindle speed of the spindle revolution (rpm) and the feed rate including the factors that influence the selection of the cutting speed.
4.1.8 State the types of coolants, function and their advantages.
4.1.9 State the safety procedures to be taken while drilling
4.2 Understand methods of holding work piece and drilling.
4.2.1 Explain the reason for holding the work piece securely while drilling.
4.2.2 Explain the types work holding devices commonly used in a drilling machine such as machine vice, machinist vice, V block and others.
4.2.3 Explain the procedures taken to drill a large hole.
4.2.4 Explain the importance of centre drilling and guided drilling.
4.2.5 Explain the uses of jigs in a drilling machine
4.2.6 Provide examples of jigs.
