Tool Guards:
Hazardous moving parts of a power tool need to be safeguarded. For
example, belts, gears, shafts, pulleys, sprockets, spindles, drums, fly
wheels, chains, or other reciprocating, rotating, or moving parts of
equipment must be guarded. Guards, as necessary, should be provided to
protect the operator and others from the following:
Safety guards must never be removed when a tool is being used. For
example, portable circular saws must be equipped with guards. An upper
guard must cover the entire blade of the saw. A retractable lower guard
must cover the teeth of the saw, except when it makes contact with the
work material. The lower guard must automatically return to the covering
position when the tool is withdrawn from the work.
Tool Safety Switches:
The following hand-held powered tools are to be equipped with a
momentary contact "on-off" control switch: drills, tappers, fastener
drivers, horizontal, vertical and angle grinders with wheels larger than
2 inches in diameter, disc and belt sanders, reciprocating saws, saber
saws, and other similar tools. These tools also may be equipped with a
lock-on control provided that turnoff can be accomplished by a single
motion of the same finger or fingers that turn it on.The following
hand-held powered tools may be equipped with only a positive "on-off"
control switch: platen sanders, disc sanders with discs 2 inches or less
in diameter; grinders with wheels 2 inches or less in diameter;
routers, planers, laminate trimmers, nibblers, shears, scroll saws and
jigsaws with blade shanks ¼-inch wide or less.Other hand-held powered
tools such as circular saws having a blade diameter greater than 2
inches, chain saws, and percussion tools without positive accessory
holding means must be equipped with a constant pressure switch that will
shut off the power when the pressure is released.
Tool Electrical Safety:
Among the chief hazards of electric-powered tools are burns and
slight shocks which can lead to injuries or even heart failure. Under
certain conditions, even a small amount of current can result in severe
injury and eventual death. A shock also can cause the user to fall off a
ladder or other elevated work surface.To protect the user from shock,
tools must either have a three-wire cord with ground and be grounded, be
double insulated, or be powered by a low-voltage isolation transformer.
Three-wire cords contain two current-carrying conductors and a
grounding conductor. One end of the grounding conductor connects to the
tool's metal housing. The other end is grounded through a prong on the
plug. Anytime an adapter is used to accommodate a two-hole receptacle,
the adapter wire must be attached to a known ground. The third prong
should never be removed from the plug.Double insulation is more
convenient. The user and the tools are protected in two ways: by normal
insulation on the wires inside, and by a housing that cannot conduct
electricity to the operator in the event of a malfunction.
Electric Power Tool General Safety Practices:
- Electric tools should be operated within their design limitations.
- Gloves and safety footwear are recommended during use of electric tools.
- When not in use, tools should be stored in a dry place.
- Electric tools should not be used in damp or wet locations.
- Work areas should be well lighted.
Powered Abrasive Wheel Tools:
Powered abrasive grinding, cutting, polishing, and wire buffing
wheels create special safety problems because they may throw off flying
fragments. Before an abrasive wheel is mounted, it should be inspected
closely and sound- or ring-tested to be sure that it is free from cracks
or defects. To test, wheels should be tapped gently with a light
non-metallic instrument. If they sound cracked or dead, they could fly
apart in operation and so must not be used. A sound and undamaged wheel
will give a clear metallic tone or "ring." To prevent the wheel from
cracking, the user should be sure it fits freely on the spindle. The
spindle nut must be tightened enough to hold the wheel in place, without
distorting the flange.
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