CAUTION (DW421 and 423 only): Never operate this tool unless the dust collector is in
place. Sanding dust exhaust may create a breathing hazard.

Operation

To operate your sander, grasp it as shown in FIG.’s 5A or 5B and turn it on. Move the unit in
long, sweeping strokes along the surface being sanded, letting the sander do the work.
Pushing down on the tool while sanding actually slows the removal rate and produces an inferior
quality surface. Be sure to check your work often, this sander is capable of removing material
rapidly, especially with coarse paper.
The random orbital action of your sander allows you to sand with the grain or at any angle
across it for most sanding jobs. To produce the best finish possible, start with coarse grit
sandpaper and change gradually to finer and finer paper. Vacuum and wipe surface with a tack
cloth between grit steps.Your sander is designed to sand into small or confined areas. Its small
size and light weight make it ideal for overhead work.
If your sander has the dust collection feature (DW421 and DW423), the rate at which the dust
collection bag fills up will vary with the type of material being sanded and the coarseness of the
sandpaper. For best results, empty the bag frequently. When sanding painted surfaces, (see the
following for additional precautions when sanding paint) you may find that the sandpaper loads
up and clogs with paint. A heat gun will work much better to remove paint before sanding.
FOLLOW ALL SAFETY INSTRUCTIONS IN HEAT GUN INSTRUCTION MANUAL.
NOTE (DW420 only): When using PSA sanding discs, remove the disc soon after operation.
PSA papers, if the disc is left on during tool storage, sometimes become difficult to remove. To
aid in the removal of old PSA paper, sand for a few minutes to soften the adhesive backing prior
to changing disc.

Precautions To Take When Sanding Paint

1. Sanding of lead based paint is NOT RECOMMENDED due to the difficulty of controlling the
contaminated dust. The greatest danger of lead poisoning is to children and pregnant women.
2. Since it is difficult to identify whether or not a paint contains lead without a chemical analysis, we
recommend the following precautions when sanding any paint:
PERSONAL SAFETY
a. No children or pregnant women should enter the work area where the paint sanding is
being done until all clean up is completed.
b.A dust mask or respirator should be worn by all persons entering the work area. The
filter should be replaced daily or whenever the wearer has difficulty breathing.
NOTE: Only those dust masks suitable for working with lead paint dust and fumes should
be used. Ordinary painting masks do not offer this protection. See your local hardware
dealer for the proper N.I.O.S.H. approved mask.
c. NO EATING, DRINKING or SMOKING should be done in the work area to prevent
ingesting contaminated paint particles. Workers should wash and clean up BEFORE
eating, drinking or smoking. Articles of food, drink, or smoking should not be left in the
work area where dust would settle on them.
ENVIRONMENTAL SAFETY
a. Paint should be removed in such a manner as to minimize the amount of dust generated.
b. Areas where paint removal is occurring should be sealed with plastic sheeting of 4 mils
thickness.
c. Sanding should be done in a manner to reduce tracking of paint dust outside the work
area.
CLEANING AND DISPOSAL
a. All surfaces in the work area should be vacuumed and thoroughly cleaned daily for the
duration of the sanding project. Vacuum filter bags should be changed frequently.
b. Plastic drop cloths should be gathered up and disposed of along with any dust chips or
other removal debris. They should be placed in sealed refuse receptacles and disposed of
through regular trash pick-up procedures. During clean up, children and pregnant women
should be kept away from the immediate work area.
c. All toys, washable furniture and utensils used by children should be washed thoroughly
before being used again.

Tool Care

1. Keep your sander as clean as possible by wiping with a clean cloth and blowing air through it
after every 5 hours of use.
2. As part of CFS (Controlled Finishing System), your sander is equipped with a replaceable
disc which is located between the pad and the shroud. It is designed to increase the dust
collection efficiency and control the pad speed while the unit is off the work. The disc is
designed to be a consumable part and will occasionally need to be replaced. Replacement is
necessary when the pad speed increases very dramatically when the unit is lifted from the
work surface. To replace your CFS disc:
a. Turn off and unplug tool.
b. Remove 3 screws from the bottom of the pad.
c. Remove the pad.
d. Snap out worn disc.
e. Snap in new disc, aligning notch in disc with cut out in shroud shown in figure 7.
f. Press in new disc around the edges using both hands to ensure that the disc is inserted
snugly into the shroud as shown in figure 8.
g. Replace the pad and the 3 screws.
3. Don’t use harsh chemicals or solvents to clean the tool. These chemicals could seriously
damage the plastic components of your sander.
4. Avoid overloading your sander. Overloading will result in a considerable reduction in speed
and finish quality of your work. The unit may also become hot. In this event, run sander at a
no load condition for a minute or two.
5. If you wrap the cord around the tool when you store it, leave a generous loop of cord such that
the strain relief does not bend. This helps prevent premature cord failure.

Brush Replacement

TURN OFF AND UNPLUG THE SANDER
Follow these directions to replace the tool’s brushes:
1. Remove the three screws located in the top cap, as shown in figure 9.
2. Lift off the top cap. Observe the brush holders and wires leading from the brushes to the motor
field, as shown in figure 10A and 10B . (NOTE: On the DW423, the speed dial must be moved
out of the way to access brush holder as shown in figure 10B.)
3. Pull the wires from the motor field and then lift and hold out of the way of one of the brush
springs.
4. Remove the old brush from the brush holder and discard the brush/wire assembly. Still holding
the brush spring out of the way, insert the new brush and release the spring against the back
of the brush. Then plug the wire into the motor field. Repeat the procedure for the second
brush.
5. Replace the top cap and tighten the three screws that hold it in place. Always replace both
brushes.

Lubrication

Self lubricating bearings are used in the tool and periodic relubrication is not required. However,
it is recommended that, once a year, you take or send the tool to a service center for a thorough
cleaning and inspection.

Repairs

To assure product SAFETY and RELIABILITY, repairs, maintenance and adjustment (including
brush inspection and replacement) should be performed by authorized service centers or other
qualified service organizations, always using identical replacement parts.

Full Warranty

DEWALT heavy duty industrial tools are warranted for one year from date of purchase. We will
repair, without charge, any defects due to faulty materials or workmanship. For warranty repair
information, call 1-800-4-DEWALT. This warranty does not apply to accessories or damage
caused where repairs have been made or attempted by others. This warranty gives you specific
legal rights and you may have other rights which vary in certain states or provinces.
In addition to the warranty, DEWALT tools are covered by our:
I
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FIG. 2FIG. 1
FIG. 3 FIG. 4
FIG. 5A
FIG. 5B
FIG. 7 FIG. 8
I
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FIG. 9
POUR TOUTE QUESTION OU REMARQUE AU SUJET DE CET OUTIL OU DE TOUT AUTRE
OUTIL DEWALT, COMPOSER LE NUMÉRO SANS FRAIS :
1 800 4-DEWALT (1 800 433-9258)

Règles de sécurité générales pour tous les outils

AVERTISSEMENT! Il faut lire et comprendre toutes les directives. Le non-respect des
directives présentées ci-dessous pourrait causer un choc électrique, un incendie et/ou des
blessures graves.

CONSERVER CES DIRECTIVES.

AIRE DE TRAVAIL
•L’aire de travail doit être propre et bien éclairée. Les établis encombrés et le manque de
lumière peuvent entraîner des accidents.
•Ne pas faire fonctionner des outils électriques dans des atmosphères explosives,
comme en présence de liquides, de gaz et de poussières inflammables. Les outils
électriques produisent des étincelles qui peuvent enflammer la poussière ou les vapeurs.
•Tenir les spectateurs, les enfants et les visiteurs à l’écart lorsqu’on utilise l’outil. Les
distractions peuvent entraîner une perte de maîtrise.
RÈGLES DE SÉCURITÉ RELATIVES À L’ÉLECTRICITÉ
•Les outils à double isolation sont pourvus d’une fiche polarisée (une lame est plus
large que l’autre). Cette fiche ne peut être branchée dans une prise polarisée que dans
un seul sens. Si la fiche ne peut être branchée dans la prise, l’inverser. Si on n’arrive
pas à la brancher, communiquer avec un électricien qualifié afin qu’il installe une prise
polarisée. Ne pas modifier la fiche. La double isolation évite de recourir à une rallonge
d’alimentation trifilaire et à un bloc d’alimentation mis à la terre.
•Éviter tout contact corporel avec des surfaces mises à la terre, comme des tuyaux,
des radiateurs, des cuisinières et des réfrigérateurs. Le risque de choc électrique
augmente si le corps est mis à la terre.
•Ne pas exposer les outils électriques à la pluie ni à l’eau. Si de l’eau pénètre dans un
outil électrique, le risque de choc électrique augmente.
•Manipuler le cordon avec soin. Ne jamais s’en servir pour transporter l’outil ou pour
FIG. 10A (DW420
AND DW421 ONLY) FIG. 10B (DW423
ONLY)
30 DAY NO RISK SATISFACTION GUARANTEE
If you are not completely satisfied with the performance of your DEWALT heavy duty industrial
tool, simply return it to the participating seller within 30 days for a full refund. Please return the
complete unit, transportation prepaid. Proof of purchase may be required.
FREE WARNING LABEL REPLACEMENT: If your warning labels become illegible or are
missing, call 1-800-4-DEWALT for a free replacement.