Makita 5903R Instruction Manual page 6

5. Hold the power tool by insulated gripping sur-
faces, when performing an operation where the
cutting tool may contact hidden wiring or its own
cord. Contact with a "live" wire will also make
exposed metal parts of the power tool "live" and
could give the operator an electric shock.
6. When ripping, always use a rip fence or straight
edge guide. This improves the accuracy of cut and
reduces the chance of blade binding.
7. Always use blades with correct size and shape
(diamond versus round) of arbour holes. Blades
that do not match the mounting hardware of the saw
will run off-centre, causing loss of control.
8. Never use damaged or incorrect blade washers
or bolt. The blade washers and bolt were specially
designed for your saw, for optimum performance and
safety of operation.
Kickback causes and related warnings
– kickback is a sudden reaction to a pinched, jammed or
misaligned saw blade, causing an uncontrolled saw to
lift up and out of the workpiece toward the operator;
– when the blade is pinched or jammed tightly by the kerf
closing down, the blade stalls and the motor reaction
drives the unit rapidly back toward the operator;
– if the blade becomes twisted or misaligned in the cut,
the teeth at the back edge of the blade can dig into the
top surface of the wood causing the blade to climb out
of the kerf and jump back toward the operator.
Kickback is the result of saw misuse and/or incorrect
operating procedures or conditions and can be avoided
by taking proper precautions as given below.
1. Maintain a firm grip with both hands on the saw
and position your arms to resist kickback forces.
Position your body to either side of the blade,
but not in line with the blade. Kickback could
cause the saw to jump backwards, but kickback
forces can be controlled by the operator, if proper
precautions are taken.
2. When blade is binding, or when interrupting a
cut for any reason, release the trigger and hold
the saw motionless in the material until the blade
comes to a complete stop. Never attempt to
remove the saw from the work or pull the saw
backward while the blade is in motion or kick-
back may occur. Investigate and take corrective
actions to eliminate the cause of blade binding.
3. When restarting a saw in the workpiece, centre
the saw blade in the kerf so that the saw teeth
are not engaged into the material. If a saw blade
binds, it may walk up or kickback from the workpiece
as the saw is restarted.
4. Support large panels to minimise the risk of
blade pinching and kickback. Large panels tend to
sag under their own weight. Supports must be
placed under the panel on both sides, near the line
of cut and near the edge of the panel. (Fig. 2 & 3)
5. Do not use dull or damaged blades. Unsharpened
or improperly set blades produce narrow kerf caus-
ing excessive friction, blade binding and kickback.
6. Blade depth and bevel adjusting locking levers
must be tight and secure before making the cut.
If blade adjustment shifts while cutting, it may cause
binding and kickback.
7. Use extra caution when sawing into existing
walls or other blind areas. The protruding blade
may cut objects that can cause kickback.
6
8. ALWAYS hold the tool firmly with both hands.
NEVER place your hand, leg or any part of your
body under the tool base or behind the saw,
especially when making cross-cuts. If kickback
occurs, the saw could easily jump backwards over
your hand, leading to serious personal injury.
(Fig. 4)
9. Never force the saw. Push the saw forward at a
speed so that the blade cuts without slowing.
Forcing the saw can cause uneven cuts, loss of
accuracy, and possible kickback.
Lower guard function
1. Check the lower guard for proper closing before
each use. Do not operate the saw if the lower
guard does not move freely and close instantly.
Never clamp or tie the lower guard into the open
position. If the saw is accidentally dropped, the
lower guard may be bent. Raise the lower guard with
the retracting handle and make sure it moves freely
and does not touch the blade or any other part, in all
angles and depths of cut.
2. Check the operation of the lower guard spring. If
the guard and the spring are not operating prop-
erly, they must be serviced before use. Lower
guard may operate sluggishly due to damaged
parts, gummy deposits, or a build-up of debris.
3. The lower guard may be retracted manually only
for special cuts such as "plunge cuts" and
"compound cuts". Raise the lower guard by the
retracting handle and as soon as the blade
enters the material, the lower guard must be
released. For all other sawing, the lower guard
should operate automatically.
4. Always observe that the lower guard is covering
the blade before placing the saw down on bench
or floor. An unprotected, coasting blade will cause
the saw to walk backwards, cutting whatever is in its
path. Be aware of the time it takes for the blade to
stop after switch is released.
5. To check lower guard, open lower guard by
hand, then release and watch guard closure.
Also check to see that retracting handle does
not touch tool housing. Leaving blade exposed is
VERY DANGEROUS and can lead to serious per-
sonal injury.
Riving knife function
1. Use the appropriate saw blade for the riving
knife. For the riving knife to function, the body of the
blade must be thinner than the riving knife and the
cutting width of the blade must be wider than the
thickness of the riving knife.
2. Adjust the riving knife as described in this
instruction manual. Incorrect spacing, positioning
and alignment can make the riving knife ineffective
in preventing kickback.
3. Always use the riving knife except when plunge
cutting. The riving knife must be replaced after
plunge cutting. The riving knife causes interference
during plunge cutting and can create kickback.
4. For the riving knife to work, it must be engaged
in the workpiece. The riving knife is ineffective in
preventing kickback during short cuts.
5. Do not operate the saw if the riving knife is bent.
Even a light interference can slow the closing rate of
a guard.