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7. DRILLING

• A very common operation that cuts cylindrical holes.

7.1 TYPES OF DRILL PRESSES

•General type of drill presses in use are,

•Sensitive - typically belt driven, and the bit is fed by hand. There are a limited choice of speeds. A bench top machine

•Vertical or Pillar - has a heavy frame to support a wider range of work. The table height is adjustable, and power speeds and feeds are available.

•Radial Arm - For very large and heavy work. The arm is power driven for the height location. The drilling head traverses the swinging arm. The workpiece remains stationary on the machine base, or work table. The machine spindle is moved to the location required.

•More specialized drill presses are,

•Gang Type - several spindles/or stations are mounted on one long table

•Multi Spindle - There are many spindles mounted on one head to allow many holes to be drilled simultaneously (e.g., up to 24)

•Numerical Control Type - The machine can automatically change tooling with a turret or automatic tool changer. Speeds, feeds and table position are controlled using a computer program.

7.2 TYPICAL DRILL PRESS OPERATIONS

• Counter Bores - Allows the head of cap screws to be sunk beneath a surface

• Spot Face - Allows the head of a bolt to be sunk beneath the surface. This is basically a shallow

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counter bore.

• Counter Sink - Allows counter sunk head screws to be sunk beneath a surface.

82°

• Center Drilling - Allows parts to be mounted between centers, on lathes typically.

• Tapers Holes - these holes can be cut using reamers.