screw. The screw shank clearance hole in the
first piece allows the screw head to pull the
pieces tightly together.
The adjustable screw drill accessory will do all
of these operations quickly and easily. Screw
drills are available for screw sizes No. 6, 8, 10
and 12.
DRILL BITS
Always inspect drill bits for excessive wear. Use
only bits that are sharp and in good condition.
TWIST BITS: Available with straight and reduced
shanks for wood and light duty metal drilling. High
speed bits cut faster and last longer on hard ma -
terials.
CARBIDE TIPPED BITS: Used for drilling stone,
con crete, plaster, cement and other unusually
hard nonmetals. Use continuous heavy feed
pres sure when employing carbide tip bits.
DRILLING WOOD
Be certain workpiece is clamped or anchored
firm ly. Always apply pressure in a straight line
with the drill bit. Maintain enough pressure to
keep the drill “biting”.
When drilling holes in wood, twist bits can be
used. Twist bits may overheat unless pulled out
frequently to clear chips from flutes.
Use a “back-up” block of wood for work that is
likely to splinter, such as thin materials.
You will drill a cleaner hole if you ease up on the
pressure just before the bit breaks through the
wood. Then complete the hole from the back
side.
DRILLING METAL
There are two rules for drilling hard materials.
First, the harder the material, the greater the
pres sure you need to apply to the tool. Second,
the harder the material, the slower the speed.
Here are a couple of tips for drilling in metal.
Lubri cate the tip of the bit occasionally with
cutting oil except when drilling soft metals such as
alu minum, cop per or cast iron. If the hole to be
drilled is fairly large, drill a smaller hole first, then
enlarge to the required size, it’s often faster in the
long run. Main tain enough pressure to assure that
the bit does not just spin in the hole. This will dull
the bit and greatly shorten its life.
Before using an accessory,
be certain that its maximum
safe operating speed is not exceeded by the
nameplate speed of the tool. Do not exceed
the recommended wheel diameter.
SANDING AND POLISHING
Fine sanding and polishing re quire “touch”. Select
the most efficient speed.
When using polishing bonnets, always be sure
the excess string that secures the bonnet is
tucked well within the bonnet during operation.
WIRE BRUSHES
Work with brushes requires high speeds.
BRUSHING PRESSURE
1. Let the tips of a wire brush do the work.
Operate the brush with the lightest pressure
so only the tips of the wire come in contact
with the work.
2. If heavier pressures are used, the wires will
be overstressed, resulting in a wiping action;
and if this is continued, the life of the brush
will be shortened due to wire fatigue.
3. Apply the brush to the work in such a way
that as much of the brush face as possible is
in full contact with the work. Applying the
side or edge of the brush to the work will
result in wire breakage and shortened brush
life.
-13-
CORRECT:
Wire tips doing the work.
INCORRECT:
Excessive pressure can cause wire breakage.
2610067278 03-21 GSR18V-190 20210317.qxp_GSR18V-190 3/17/21 3:40 PM Page 13
