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Pilot Hole Pilot holes are smaller holes drilled first before a large hole is drilled. In the picture we see the pilot holes that are drilled in the body of a computer before they are drilled with a larger bit. Blind Hole A blind hole is a hole that is not drilled the whole way through like in the in the sketch shown. Pilot Hole De-burring is removing the burr from hole with a large drill bit or de-burring tool Tapping Hole A tapping hole is similar to a pilot hole. For a thread to be cut or “tapped” the hole must be smaller than the size of the thread. The chart on the right is a guide to the size hole that should be drilled when drilling a tapping hole
Countersinking is where the mouth of the drill hole is enlarged . This is done so that a countersunk screw will sit flush with the surface.  Counter boring is drilling down to make the hole wider to a certain depth  This is done so that a cheese-head screw will sit flush with the surface.

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M3 2.5 mm
M4 3.3 mm
M5 4.2 mm
M6 5.0 mm
M7 6.0 mm
M8 6.8 – 7.0 mm
M10 8.5 – 9.0 mm
M12 10.2 – 10.5 mm
M14 12.0 – 12.5 mm
M16 14.0 – 14.5 mm

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This is the drill that we use in the metalwork room .

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This is a high risk machine. Great care must be taken when using it. Safety gear must be worn at all times.

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• No loose clothing • Hair tied back • Always wear safety goggles • Have the piece to be drilled secure in the vice or clamp • Make sure the drill bit is secure in the chuck • Use cutting fluid if needed • If anything goes wrong, hit the emergency stop button straight away and tell the teacher • If the piece comes out of the vice and is spinning with the chuck, DO NOT ATTEMPT TO STOP IT WITH YOUR HAND, hit the emergency stop button and wait for the chuck to stop spinnin

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Emergency Stop Button If there is any problem with the drill, this button cuts off the power   Chuck This holds the drill bit  . To tighten the chuck, use the chuck key  Table A vice can be attached to the table to hold a piece for drilling Column Supports the drill Base Keeps the entire drill balanced when in use  Height Adjuster This handle can move the table up or down via a rack and pinion Feed lever By turning this, the chuck is moved up and down for drilling Motor Turns the pulleys which causes the chuck to spin for drilling

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Counter boring is drilling down to make the hole wider to a certain depth (like in the picture). This is done so that a cheese-head screw will sit flush with the surface.

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Countersinking is where the mouth of the drill hole is enlarged (like in the picture). This is done so that a countersunk screw will sit flush with the surface.

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• Centre punch where the hole is to be drilled • Secure the piece into the drill’s vice • Place a piece of wood under it if needed • Select the correct size drill bit • Make sure the drill bit is secure in the chuck • Select the correct drilling speed • Use cutting fluid if needed • Drill through the piece • Turn off the drill • Wait for the chuck to stop spinning and removed the piece • De-burr the hole