Figure 12-4.Eye shields for bench and
pedestal type of grinders.
prevent work from being wedged between the tool
rest and the wheel. Turn the wheel by hand after
adjusting the tool rest to ensure there is satisfactory
clearance completely around the wheel (fig. 12-5).
The grinding wheels themselves can be sources
of danger and should be examined frequently, based
upon usage, for irregularities and soundness. You can
test a new wheel by suspending it on a string or wire
and tapping the side of the wheel with a light metal
rod. A solid wheel will give off a distinct ringing
sound, A wheel that does not give off such a sound
must be assumed to be cracked and should be
discarded. Under no circumstances should it be used.
Since it is not practical to check the wheels by this
manner every time you use the grinder, make it a
habit never to stand in front of a grinder when it is
first turned on. A cracked wheel can disintegrate and
become projectiles quickly.
The wheel must also run true and be balanced on
the shaft. A WHEEL DRESSER (fig. 12-6) should be
used to bring abrasive wheels back to round and
Figure 12-5.Properly spaced tool rest.
Figure 12-6.Mechanical wheel dresser.
remove the glaze that occurs after heavy use. This is
done by holding the dresser firmly against the wheel
with both hands, using the tool rest for support.
Then, as the wheel turns, move the dresser back and
forth across the surface (fig. 12-7). For maximum
efficiency and safety in operating the grinder, you
should observe the following rules:
1. Use the face of the wheel, never the sides.
2. Move the work back and forth across the face
of the wheel. Even wear results because this action
prevents the wheel from becoming grooved.
3. Keep the wheel dressed and the tool rest
Do not shape soft metals, like aluminum, brass,
and copper, that tend to load (clog) the abrasive
wheel. These metals should be shaped by other
methods, such as tiling, sanding, and chipping.
PNEUMATIC POWER TOOLS
The portable power tools that are available for use
are either powered by electric motors or by air
(pneumatic) motors. Whether powered by electricity
or compressed air, the tools are basically the same
and the procedures for using them are the same. This
section will deal with pneumatic tools since these
require unique maintenance and servicing on the
jobsite or in the shop.
NOTE: All low-pressure compressed air systems
should have a filter, a regulator, and a lubricator
assembly installed at the outlet. This assembly will
ensure delivery of clean, regulated mist lubricated
compressed air for the operation of pneumatic tools.
Figure 12-7.Using a wheel dresser.