DeWalt DW840 User manual

DW831, DW840
5" (125 mm) and 7" (180 mm) Heavy Duty Angle Grinder
Rectifieuse coudée de service intensif de 127 mm (5 po) et 180 mm (7po)
Esmeriladora angular para trabajo pesado de 127 mm (5") y 180 mm (7")
INSTRUCTION MANUAL
GUIDE D’UTILISATION
MANUAL DE INSTRUCCIONES
INSTRUCTIVO DE OPERACIÓN, CENTROS DE SERVICIO Y PÓLIZA DE
GARANTÍA. ADVERTENCIA: LÉASE ESTE INSTRUCTIVO ANTES DE
USAR EL PRODUCTO.
If you have questions or comments, contact us.
Pour toute question ou tout commentaire, nous contacter.
Si tiene dudas o comentarios, contáctenos.
1-800-4-D
e
WALT • www.dewalt.com
FINAL PRINT SIZE: 5.5 x 8.5"

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Definitions: Safety Guidelines
The definitions below describe the level of severity for each
signal word. Please read the manual and pay attention to these
symbols.
DANGER: Indicates an imminently hazardous situation
which, if not avoided, will result in death or serious injury.
WARNING: Indicates a potentially hazardous situation which,
if not avoided, could result in death or serious injury.
CAUTION:Indicates a potentially hazardous situation which, if
not avoided, may result in minor or moderate injury.
NOTICE: Indicates a practice not related to personal injury
which, if not avoided, may result in property damage.
IF YOU HAVE ANY QUESTIONS OR COMMENTS ABOUT THIS OR
ANY D
e
WALT TOOL, CALL US TOLL FREE AT: 1-800-4-D
e
WALT
(1-800-433-9258).
WARNING: To reduce the risk of injury, read the instruction
manual.
General Power Tool Safety Warnings
WARNING! Read all safety warnings and all instructions.
Failure to follow the warnings and instructions may result in
electric shock, fire and/or serious injury.
SAVE ALL WARNINGS AND INSTRUCTIONS
FOR FUTURE REFERENCE
The term “power tool” in the warnings refers to your mains-operated
(corded) power tool or battery-operated (cordless) power tool.
1) WORK AREA SAFETY
a) Keep work area clean and well lit. Cluttered or dark areas
invite accidents.
b) Do not operate power tools in explosive atmospheres,
such as in the presence of flammable liquids, gases or
dust. Power tools create sparks which may ignite the dust or
fumes.
c) Keep children and bystanders away while operating a
power tool. Distractions can cause you to lose control.
2) ELECTRICAL SAFETY
a) Power tool plugs must match the outlet. Never modify
the plug in any way. Do not use any adapter plugs with
earthed (grounded) power tools. Unmodified plugs and
matching outlets will reduce risk of electric shock.
b) Avoid body contact with earthed or grounded surfaces
such as pipes, radiators, ranges and refrigerators. There
is an increased risk of electric shock if your body is earthed or
grounded.
c) Do not expose power tools to rain or wet conditions.
Water entering a power tool will increase the risk of electric
shock.
d) Do not abuse the cord. Never use the cord for carrying,
pulling or unplugging the power tool. Keep cord away
from heat, oil, sharp edges or moving parts. Damaged or
entangled cords increase the risk of electric shock.
e) When operating a power tool outdoors, use an extension
cord suitable for outdoor use. Use of a cord suitable for
outdoor use reduces the risk of electric shock.
f) If operating apower tool in adamp location is unavoidable,
use a ground fault circuit interrupter (GFCI) protected
supply. Use of a GFCI reduces the risk of electric shock.

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3) PERSONAL SAFETY
a) Stay alert, watch what you are doing and use common
sense when operating a power tool. Do not use a power
tool while you are tired or under the influence of drugs,
alcohol or medication. A moment of inattention while
operating power tools may result in serious personal injury.
b) Use personal protective equipment. Always wear eye
protection. Protective equipment such as dust mask, non-
skid safety shoes, hard hat, or hearing protection used for
appropriate conditions will reduce personal injuries.
c) Prevent unintentional starting. Ensure the switch is in
the off position before connecting to power source and/
or battery pack, picking up or carrying the tool. Carrying
power tools with your finger on the switch or energizing power
tools that have the switch on invites accidents.
d) Remove any adjusting key or wrench before turning the
power tool on. A wrench or a key left attached to a rotating
part of the power tool may result in personal injury.
e) Do not overreach. Keep proper footing and balance at
all times. This enables better control of the power tool in
unexpected situations.
f) Dress properly. Do not wear loose clothing or jewelry.
Keep your hair, clothing and gloves away from moving
parts. Loose clothes, jewelry or long hair can be caught in
moving parts.
g) If devices are provided for the connection of dust
extraction and collection facilities, ensure these are
connected and properly used. Use of dust collection can
reduce dust-related hazards.
4) POWER TOOL USE AND CARE
a) Do not force the power tool. Use the correct power tool
for your application. The correct power tool will do the job
better and safer at the rate for which it was designed.
b) Do not use the power tool if the switch does not turn it
on and off. Any power tool that cannot be controlled with the
switch is dangerous and must be repaired.
c) Disconnect the plug from the power source and/or the
battery pack from the power tool before making any
adjustments, changing accessories, or storing power
tools. Such preventive safety measures reduce the risk of
starting the power tool accidentally.
d) Store idle power tools out of the reach of children and
do not allow persons unfamiliar with the power tool or
these instructions to operate the power tool. Power tools
are dangerous in the hands of untrained users.
e) Maintain power tools. Check for misalignment or binding
of moving parts, breakage of parts and any other
condition that may affect the power tool’s operation. If
damaged, have the power tool repaired before use. Many
accidents are caused by poorly maintained power tools.
f) Keep cutting tools sharp and clean. Properly maintained
cutting tools with sharp cutting edges are less likely to bind and
are easier to control.
g) Use the power tool, accessories and tool bits, etc. in
accordance with these instructions, taking into account
the working conditions and the work to be performed.
Use of the power tool for operations different from those
intended could result in a hazardous situation.
5) SERVICE
a) Have your power tool serviced by a qualified repair
person using only identical replacement parts. This will
ensure that the safety of the power tool is maintained.

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SAFETY INSTRUCTIONS FOR
ALL OPERATIONS
Safety Warnings Common for Grinding,
Sanding, Wire Brushing, Polishing or
Abrasive, Cutting-Off Operations
a) This power tool is intended to function as a grinder,
sander, wire brush or polisher. Read all safety warnings,
instructions, illustrations and specifications provided
with this power tool. Failure to follow all instructions listed
below may result in electric shock, fire and/or serious injury.
b) Cutting-off is not recommended to be performed with
this power tool. Operations for which the power tool was not
designed may create a hazard and cause personal injury.
c) Do not use accessories which are not specifically
designed and recommended by the tool manufacturer.
Just because the accessory can be attached to your power
tool, it does not assure safe operation.
d) The rated speed of the accessory must be at least
equal to the maximum speed marked on the power tool.
Accessories running faster than their rated speed can break
and fly apart.
e) The outside diameter and the thickness of your accessory
must be within the capacity rating of your power tool.
Incorrectly sized accessories cannot be adequately guarded or
controlled.
f) Threaded mounting of accessories must match the
grinder spindle thread. For accessories mounted by
flanges, the arbor hole of the accessory must fit the
locating diameter of the flange. Accessories that do not
match the mounting hardware of the power tool will run out of
balance, vibrate excessively and may cause loss of control.
g) Do not use a damaged accessory. Before each use
inspect the accessory such as abrasive wheels for chips
and cracks, backing pad for cracks, tear or excess wear,
wire brush for loose or cracked wires. If power tool or
accessory is dropped, inspect for damage or install an
undamaged accessory. After inspecting and installing an
accessory, position yourself and bystanders away from
the plane of the rotating accessory and run the power
tool at maximum no-load speed for one minute. Damaged
accessories will normally break apart during this test time.
h) Wear personal protective equipment. Depending on
application, use face shield, safety goggles or safety
glasses. As appropriate, wear dust mask, hearing
protectors, gloves and workshop apron capable of
stopping small abrasive or workpiece fragments. The eye
protection must be capable of stopping flying debris generated
by various operations. The dust mask or respirator must be
capable of filtrating particles generated by your operation.
Prolonged exposure to high intensity noise may cause hearing
loss.
i) Keep bystanders a safe distance away from work area.
Anyone entering the work area must wear personal
protective equipment. Fragments of workpiece or of a
broken accessory may fly away and cause injury beyond
immediate area of operation.
j) Hold the power tool by insulated gripping surfaces
only, when performing an operation where the cutting
accessory may contact hidden wiring or its own cord.
Cutting accessory contacting a “live” wire may make exposed
metal parts of the power tool “live” and shock the operator.
k) Position the cord clear of the spinning accessory. If you
lose control, the cord may be cut or snagged and your hand or
arm may be pulled into the spinning accessory.

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l) Never lay the power tool down until the accessory has
come to a complete stop. The spinning accessory may grab
the surface and pull the power tool out of your control.
m) Do not run the power tool while carrying it at your side.
Accidental contact with the spinning accessory could snag
your clothing, pulling the accessory into your body.
n) Regularly clean the power tool’s air vents. The motor’s
fan will draw the dust inside the housing and excessive
accumulation of powdered metal may cause electrical hazards.
o) Do not operate the power tool near flammable materials.
Sparks could ignite these materials.
p) Do not use accessories that require liquid coolants.
Using water or other liquid coolants may result in electrocution
or shock.
q) Do not use Type 11 (flaring cup) wheels on this tool. Using
inappropriate accessories can result in injury.
r) Always use side handle. Tighten the handle securely.The
side handle should always be used to maintain control of the
tool at all times.
s) When starting the tool with a new or replacement wheel,
or a new or replacement wire brush installed, hold the
tool in a well protected area and let it run for one minute.
If the wheel has an undetected crack or flaw, it should burst in
less than one minute. If the wire brush has loose wires, they will
be detected. Never start the tool with a person in line with the
wheel. This includes the operator.
t) Use of accessories not specified in this manual is not
recommended and may be hazardous. Use of power
boosters that would cause the tool to be driven at speeds
greater than its rated speed constitutes misuse.
u) Use clamps or another practical way to secure and
support the workpiece to a stable platform. Holding the
work by hand or against your body leaves it unstable and may
lead to loss of control.
v) Avoid bouncing the wheel or giving it rough treatment.
If this occurs, stop the tool and inspect the wheel for cracks or
flaws.
w) Always handle and store wheels in a careful manner.
x) Do not operate this tool for long periods of time. Vibration
caused by the operating action of this tool may cause
permanent injury to fingers, hands, and arms. Use gloves to
provide extra cushion, take frequent rest periods, and limit daily
time of use.
Causes and Operator Prevention
of Kickback
Kickback is a sudden reaction to a pinched or snagged rotating
wheel, backing pad, brush or any other accessory. Pinching or
snagging causes rapid stalling of the rotating accessory which
in turn causes the uncontrolled power tool to be forced in the
direction opposite of the accessory’s rotation at the point of the
binding.
For example, if an abrasive wheel is snagged or pinched by the
workpiece, the edge of the wheel that is entering into the pinch
point can dig into the surface of the material causing the wheel
to climb out or kick out. The wheel may either jump toward or
away from the operator, depending on direction of the wheel’s
movement at the point of pinching. Abrasive wheels may also
break under these conditions.
Kickback is the result of tool misuse and/or incorrect operating
procedures or conditions and can be avoided by taking proper
precautions as given below:
a) Maintain a firm grip on the power tool and position your
body and arm to allow you to resist kickback forces.

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Always use auxiliary handle, if provided, for maximum
control over kickback or torque reaction during start up.
The operator can control torque reaction or kickback forces, if
proper precautions are taken.
b) Never place your hand near the rotating accessory.
Accessory may kickback over your hand.
c) Do not position your body in the area where power tool
will move if kickback occurs. Kickback will propel the tool
in direction opposite to the wheel’s movement at the point of
snagging.
d) Use special care when working corners, sharp edges etc.
Avoid bouncing and snagging the accessory. Corners,
sharp edges or bouncing have a tendency to snag the rotating
accessory and cause loss of control or kickback.
e) Do not attach a saw chain woodcarving blade or toothed
saw blade. Such blades create frequent kickback and loss of
control.
Safety Warnings Specific for Grinding
Operations
a) Use only wheel types that are recommended for your
power tool and the specific guard designed for the
selected wheel. Wheels for which the power tool was not
designed cannot be adequately guarded and are unsafe.
b) The grinding surface of center depressed wheels must
be mounted below the plane of the guard lip. An
improperly mounted whe`el that projects through the plane of
the guard lip cannot be adequately protected.
c) The guard must be securely attached to the power tool
and positioned for maximum safety, so the least amount
of wheel is exposed towards the operator. The guard helps
to protect operator from broken wheel fragments, accidental
contact with wheel and sparks that could ignite clothing.
d) Wheels must be used only for recommended applications.
For example: do not grind with the side of cut-off wheel.
Abrasive cut-off wheels are intended for peripheral grinding,
side forces applied to these wheels may cause them to shatter.
e) Always use undamaged wheel flanges that are of correct
size and shape for your selected wheel. Proper wheel
flanges support the wheel thus reducing the possibility of wheel
breakage. Flanges for cut-off wheels may be different from
grinding wheel flanges.
f) Do not use worn down wheels from larger power tools.
Wheel intended for larger power tool is not suitable for the
higher speed of a smaller tool and may burst.
Safety Warnings Specific for Sanding
Operations
a) Do not use excessively oversized sanding disc paper.
Follow manufacturers recommendations, when selecting
sanding paper. Larger sanding paper extending beyond the
sanding pad presents a laceration hazard and may cause
snagging, tearing of the disc or kickback.
Safety Warnings Specific for Polishing
Operations
a) Do not allow any loose portion of the polishing bonnet
or its attachment strings to spin freely. Tuck away or
trim any loose attachment strings. Loose and spinning
attachment strings can entangle your fingers or snag on the
workpiece.
Safety Warnings Specific for Wire
Brushing Operations
a) Be aware that wire bristles are thrown by the brush even
during ordinary operation. Do not overstress the wires

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by applying excessive load to the brush. The wire bristles
can easily penetrate light clothing and/or skin.
b) If the use of a guard is recommended for wire brushing,
do not allow any interference of the wire wheel or brush
with the guard. Wire wheel or brush may expand in diameter
due to work and centrifugal forces.
c) Safety goggles or safety glasses with side shields and a
full face shield compliant with ANSI Z87.1 MUST be worn
by the operator and others that are within 50' (15.2 m) of
the use of this product.
Additional Safety Information
• Air vents often cover moving parts and should be avoided.
Loose clothes, jewelry or long hair can be caught in moving parts.
• An extension cord must have adequate wire size (AWG
or American Wire Gauge) for safety. The smaller the gauge
number of the wire, the greater the capacity of the cable, that is
16 gauge has more capacity than 18 gauge. An undersized cord
will cause a drop in line voltage resulting in loss of power and
overheating. When using more than one extension to make up the
total length, be sure each individual extension contains at least the
minimum wire size. The following table shows the correct size to
use depending on cord length and nameplate ampere rating. If in
doubt, use the next heavier gauge. The smaller the gauge number,
the heavier the cord.
Minimum Gauge for Cord Sets
Ampere
Rating
Volts Total Length of Cord
in Feet (meters)
120 V 25
(7.6) 50 (15.2) 100 (30.5) 150 (45.7)
240 V 50
(15.2) 100 (30.5) 200 (61.0) 300 (91.4)
More
Than
Not
More
Than AWG
0 6 18 16 16 14
610 18 16 14 12
10 12 16 16 14 12
12 16 14 12 Not Recommended
WARNING: ALWAYS use safety glasses. Everyday eyeglasses are
NOT safety glasses. Also use face or dust mask if cutting operation is
dusty. ALWAYS WEAR CERTIFIED SAFETY EQUIPMENT:
• ANSI Z87.1 eye protection (CAN/CSA Z94.3),
• ANSI S12.6 (S3.19) hearing protection,
• NIOSH/OSHA/MSHA respiratory protection.
WARNING: Some dust created by power sanding, sawing,
grinding, drilling, and other construction activities contains chemicals
known to the State of California to cause cancer, birth defects or other
reproductive harm. Some examples of these chemicals are:
• lead from lead-based paints,
• crystalline silica from bricks and cement and other masonry
products, and
• arsenic and chromium from chemically-treated lumber.
Your risk from these exposures varies, depending on how often you
do this type of work. To reduce your exposure to these chemicals:

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work in a well ventilated area, and work with approved safety
equipment, such as those dust masks that are specially designed to
filter out microscopic particles.
• Avoid prolonged contact with dust from power sanding,
sawing, grinding, drilling, and other construction activities.
Wear protective clothing and wash exposed areas with
soap and water. Allowing dust to get into your mouth, eyes, or
lay on the skin may promote absorption of harmful chemicals.
WARNING: Use of this tool can generate and/or disperse dust,
which may cause serious and permanent respiratory or other
injury. Always use NIOSH/OSHA approved respiratory protection
appropriate for the dust exposure. Direct particles away from face
and body.
WARNING: Always wear proper personal hearing protection
that conforms to ANSI S12.6 (S3.19) during use. Under some
conditions and duration of use, noise from this product may
contribute to hearing loss.
WARNING: When not in use, place grinder on a stable
surface where it will not move inadvertantly, roll or cause a
tripping or falling hazard. Serious personal injury may result.
WARNING: The grinding wheel or accessory may loosen
during coast-down of the tool when shut off. If grinding wheel or
accessory loosens, it may dismount from the machine and may cause
serious personal injury.
CAUTION: To reduce the risk of personal injury, use extra care
when working into a corner or edge because a sudden, sharp
movement of the tool may be experienced when the wheel or other
accessory contacts a secondary surface or a surface edge.
• The label on your tool may include the following symbols. The
symbols and their definitions are as follows:
V................... volts A....................... amperes
Hz................. hertz W...................... watts
min............... minutes or AC........... alternating
or DC.. direct current current
................. Class I Construction or AC/DC ... alternating
(grounded) ......................... or direct
................ Class II Construction current
(double insulated) no..................... no load speed
…/min.......... per minute n ....................... rated speed
BPM............. beats per minute ...................... earthing
IPM .............. impacts per minute terminal
RPM............. revolutions per ...................... safety alert
minute symbol
sfpm............. surface feet SPM ................ strokes per
....................per minute ........................ minute
................visible .................... eye
....................radiation ........................ protection
................respiratory .................... hearing
protection protection

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SAVE THESE INSTRUCTIONS
FOR FUTURE USE
Motor
Be sure your power supply agrees with the nameplate marking.
Voltage decrease of more than 10% will cause loss of power and
overheating. D
e
WALT tools are factory tested; if this tool does not
operate, check power supply.
A
B
C
D
E
FIG. 1
COMPONENTS (FIG. 1)
WARNING: Never modify the power tool or any part of it. Damage
or personal injury could result.
A. On/Off switch D. Side handle
B. Lock off button E. Guard (Type 27, open beneath
C. Spindle lock button wheel or accessory)
ASSEMBLY AND ADJUSTMENTS
WARNING: To reduce the risk of injury, turn FIG. 2
D
unit off and disconnect it from power source
before installing and removing accessories,
before adjusting or when making repairs. An
accidental start-up can cause injury.
Attaching Side Handle (Fig. 2)
The side handle (D) can be fitted to either side of
the gear case in the threaded holes, as shown.
Before using the tool, check that the handle is
tightened securely.
Accessories
The capacity of the DW831 is 5" (125 mm)
diameter x 1/4" (6.35 mm) thick grinding wheels.
The capacity of the DW840 is 7" (180 mm) diameter x 1/4" (6.35 mm)
thick grinding wheels.
It is important to choose the correct guards, backing pads and flanges
to use with grinder accessories. See pages 10–11 for information on
choosing the correct accessories.
WARNING: Handle and store all abrasive wheels carefully to
prevent damage from thermal shock, heat, mechanical damage, etc.
Store in a dry protected area free from high humidity, freezing
temperatures or extreme temperature changes.
CAUTION:Accessories must be rated for at least the speed
recommended on the tool warning label. Wheels and other
accessories running over their rated speed may fly apart and cause
injury. Threaded accessories must have a 5/8" – 11 hub. Every
unthreaded accessory must have a 7/8" arbor hole. If it does not, it
may have been designed for a circular saw. Use only the accessories
shown on pages 10–11 of this manual. Accessory ratings must
always be above listed tool speed as shown on tool nameplate.