Drilling speeds
Important factors when determining the best drilling speed:
• Material type
• Hole size
• Drill bit or cutter type
• Quality desired
Smaller drill bits require greater speed than large drill bits. Softer materials require greater
speed than harder materials. See page 23 for recommended speeds for the workpiece
material.
Drilling metal
• Use metal-piercing twist drill bits.
• It is always necessary to lubricate the tip of the drill with oil to prevent overheating the
drill bit.
• All metal workpieces should be clamped down securely. Any tilting, twisting, or shifting
causes a rough drill hole, and increases the potential of drill bit breakage.
• Never hold a metal workpiece with your bare hands. The cutting edge of the drill bit may
seize the workpiece and throw it, causing serious injury. The drill bit will break if the metal
piece suddenly hits the column.
• If the metal is flat, clamp a piece of wood under it to prevent turning. If it cannot be laid flat
on the table, then it should be blocked and clamped.
Drilling wood
• Brad point bits are preferred. Metal piercing twist bits may be used on wood.
• DO NOT use auger bits. Auger bits turn so rapidly that they can lift the workpiece off of the
table and whirl it around.
• ALWAYS PROTECT THE DRILL BIT by positioning the table so that the drill bit will enter the
centre hole when drilling through the workpiece.
• To prevent splintering, feed drill bit slowly when the bit is about to cut through to the backside
of the workpiece.
• To reduce splintering and protect the point of the bit, use scrap wood as a backing or a base
block under the workpiece.
Feeding the drill bit
• Pull down on the feed handles with only enough force to allow the drill bit to cut.
• FEEDING TOO RAPIDLY might stall the motor, cause the belt to slip, damage the workpiece,
or break the drill bit.
• FEEDING TOO SLOWLY will cause the drill bit to heat up and burn the workpiece.
VII. Operation ... continued
22
