241-0342
BRUSHLESS 3/8’’ IMPACT
WRENCH
OPERATOR’S MANUAL
CAUTION:
To Reduce the Risk of Injury, User Must
Read and Understand the Operator’s Manual. Save These
Instructions For Future Reference.
For questions / comments, technical assistance or repair parts –
Please Call Toll Free: 1-866-917-4374 (M-F 8:30am-5:00pm EST).
TABLE OF CONTENTS
Safety Symbols ......................................................... Page 2
Safety Instructions ...................................................... Page 3
Overview/Specications ................................................. Page 8
Assembly ............................................................. Page 9
Operation ............................................................. Page 9
Maintenance .......................................................... Page 14
Troubleshooting ....................................................... Page 14
Warranty .............................................................Page 18
Page 2
SAFETY SYMBOLS
Some of these following symbols may be used on this tool. Please study them and learn their
meaning. Proper interpretation of these symbols will allow you to operate the tool better and
more safely.
Symbol
Name
Designation / Explanation
V Volts Voltage
A Amperes Current
Hz Hertz Frequency (cycles per second)
W Watts Power
lbs Pounds Weight
n
o
No-load speed Rotational speed at no load
RPM
Revolutions per min-
ute
Unit of speed
IPM Impacts per minute Unit of impact frequency
�
or d.c.
Direct current Type of characteristic of current
Read instruction
manual
To reduce the risk of injury, user must
read instruction manual.
WARNING:
To ensure safety and reliability, all repairs should be performed by a
qualified service technician.
Page 3
SAFETY INSTRUCTIONS
The purpose of safety symbols is to attract your attention to possible dangers. The safety
symbols, and the explanations with them, deserve your careful attention and understand-
ing. The symbol warnings do not, by themselves, eliminate any danger. The instructions and
warnings they give are no substitutes for proper accident prevention measures.
WARNING:
Be sure to read and understand all safety instructions in this manual,
including all safety alert symbols such as “DANGER”, “WARNING” and “CAUTION” before
using this tool. Failure to follow all instructions listed below may result in electric shock,
fire, and/or serious personal injury.
SYMBOL MEANING
SAFETY ALERT SYMBOL: Indicates DANGER, WARNING, OR CAUTION. May be used
in conjunction with other symbols or pictographs.
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, could
result in minor or moderate injury.
NOTICE: (Without Safety Alert Symbol) Indicates a situation that may result in property
damage.
SAVE THESE INSTRUCTIONS!
Page 4
SAFETY INSTRUCTIONS
GENERAL POWER TOOL
SAFETY WARNINGS
WARNING:
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, re 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.
WORK AREA SAFETY
1. Keep work area clean and well lit.
Cluttered or dark areas invite accidents.
2. 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.
3. Keep children and bystanders away
while operating a power tool. Distractions
can cause you to lose control.
ELECTRICAL SAFETY
1. 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. Unmodied plugs
and matching outlets will reduce risk of
electric shock.
2. 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.
3. Do not expose power tools to rain or
wet conditions. Water entering a power tool
will increase the risk of electric shock.
4. 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.
5. 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.
6. If operating a power tool in a damp
location is unavoidable, use a ground fault
circuit interrupter (GFCI) protected supply.
Use of an GFCI reduces the risk of electric
shock.
PERSONAL SAFETY
1. 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.
2. Use personal protective equipment.
Always wear eye protection. Protective
equipment such as a dust mask, non-skid
safety shoes, hard hat or hearing protection
used for appropriate conditions will reduce
personal injuries.
3. 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 nger on the
switch or energizing power tools that have
the switch on invites accidents.
4. 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.
5. Do not overreach. Keep proper footing
and balance at all times. This enables better
control of the power tool in unexpected
situations.
Page 5
SAFETY INSTRUCTIONS
6. Dress properly. Do not wear loose
clothing or jewelry. Keep your hair and
clothing away from moving parts. Loose
clothes, jewelry or long hair can be caught
in moving parts.
7. 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.
8. Do not let familiarity gained from
frequent use of tools allow you to become
complacent and ignore tool safety
principles. A careless action can cause
severe injury within a fraction of a second.
POWER TOOL USE AND CARE
1. 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.
2. 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.
3. Disconnect the plug from the power
source and/or remove the battery pack,
if detachable, 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.
4. 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.
5. Maintain power tools and accessories.
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.
6. Keep cutting tools sharp and clean.
Properly maintained cutting tools with sharp
cutting edges are less likely to bind and are
easier to control.
7. 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.
8. Keep handles and grasping surfaces
dry, clean and free from oil and grease.
Slippery handles and grasping surfaces do
not allow for safe handling and control of the
tool in unexpected situations.
BATTERY TOOL USE
AND CARE
1. Recharge only with the charger
specified by the manufacturer. A charger
that is suitable for one type of battery pack
may create a risk of re when used with
another battery pack.
2. Use power tools only with specifically
designated battery packs. Use of any other
battery packs may create a risk of injury and
re.
3. When battery pack is not in use, keep
it away from other metal objects, like
paper clips, coins, keys, nails, screws or
other small metal objects, that can make
a connection from one terminal to another.
Shorting the battery terminals together may
cause burns or a re.
4. Under abusive conditions, liquid may
be ejected from the battery; avoid contact.
If contact accidentally occurs, flush with
water. If liquid contacts eyes, additionally
seek medical help. Liquid ejected from the
battery may cause irritation or burns.
5. Do not use a battery pack or tool that
is damaged or modified. Damaged or
modied batteries may exhibit unpredictable
behavior resulting in re, explosion or risk of
injury.
Page 6
SAFETY INSTRUCTIONS
6. Do not expose a battery pack or tool
to fire or excessive temperature. Exposure
to re or temperature above 265°F (130 °C)
may cause explosion.
7. Follow all charging instructions and
do not charge the battery pack or tool
outside the temperature range specified
in the instructions. Charging improperly or
at temperatures outside the specied range
may damage the battery and increase the
risk of re.
SERVICE
1. 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.
2. Never service damaged battery
packs. Service of battery packs should
only be performed by the manufacturer or
authorized service providers.
IMPACT WRENCH SAFETY
WARNINGS
SAFETY INSTRUCTIONS FOR
ALL OPERATIONS
• Hold the power tool by insulated
gripping surfaces, when performing an
operation where the fastener may contact
hidden wiring. Fasteners contacting a “live”
wire may make exposed metal parts of the
power tool “live” and could give the operator
an electric shock.
IMPORTANT SAFETY
INSTRUCTIONS
1. To reduce the risk of electric shock
or damage to the chargers and batteries,
use only with the MASTERFORCE
®
battery
packs and chargers listed.
Battery pack Charger
252-8031 (2.0Ah)
252-8030 (2.5Ah)
252-8003 (2.5Ah)
252-8034 (4.0Ah)
252-8013 (4.0Ah)
252-8035 (5.0Ah)
252-8005 (5.0Ah)
252-8007 (7.5Ah)
252-8014 (8.0Ah)
252-8025
252-8037
252-8026
252-8043
2. For best results, your battery and tool
should be stored, charged and used in a
location where the temperature is more
than 41°F (5 °C) but less than 104°F (40 °C).
Do not store outside or in vehicles.
DANGER:
People with electronic
devices, such as pacemakers, should
consult their physician(s) before using this
product. Operation of electrical equipment
in close proximity to a heart pacemaker
could cause interference or failure of the
pacemaker.
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, cement, and
other masonry products
– Arsenic and chromium from chemically-
treated lumber
Page 7
• Your risk from these exposures varies,
depending upon how often you do this type
of work. To reduce your exposure to these
chemicals:
– Work in a well-ventilated area.
– Work with approved safety equipment,
such as dust masks that are specially
designed to lter 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 or eyes or to lie
on the skin may promote absorption of
harmful chemicals.
SAVE THESE INSTRUCTIONS!
SAFETY INSTRUCTIONS
Page 8
OVERVIEW
Trigger Switch
LED Work Light
Speed Control Panel
3/8’’ Square
Driver
Direction-of-
Rotation Selector
SPECIFICATIONS
Rated Voltage 20 V d.c.
No-load Speed 1: 0-1500 RPM
2: 0-2100 RPM
3: 0-2800 RPM
Impact Rate 1: 0-1900 IPM
2: 0-3200 IPM
3: 0-3800 IPM
Fastening Torque 1: 100 ft.lb
2: 150 ft.lb
3: 200 ft.lb
Nut Busting Torque 225 ft.lbs
Driver 3/8’’ square drive with friction ring
Weight (Without battery) 2 lbs. 5 oz. (1.06 Kg)
Page 9
OPERATION
WARNING:
If any part is broken or
missing, DO NOT attach the battery pack
or operate the tool until the broken or
missing part is replaced. Failure to do so
could result in possible serious injury.
WARNING:
Do not attempt to
modify this tool or create accessories not
recommended for use with this tool. Any
such alteration or modification is misuse
and could result in a hazardous condition
leading to possible serious injury.
WARNING:
Your tool should
never be connected to the battery pack
when you are assembling parts, making
adjustments, cleaning, or when it is not in
use. Disconnecting the tool will prevent
accidental starting, which could cause
serious personal injury.
ASSEMBLY
PACKING LIST
Cordless impact wrench, belt clip, screw, and
instruction manual.
UNPACKING
1. Carefully remove the tool and any
accessories from the carton. Make sure
that all items listed in the packing list are
included.
2. Inspect the tool carefully to make sure
that no breakage or damage occurred
during shipping.
3. Do not discard the packing material
until you have carefully inspected and
satisfactorily operated the tool.
ATTACHING BATTERY PACK
(FIG. 1)
FIG. 1
Battery-Release
Button
1. Align the raised ribs on the battery pack
with the grooves on the bottom of the
tool, then slide the battery pack onto the
tool.
2. Ensure that the battery-release button
on the battery pack snaps into place
and the battery pack is secured to the
tool before beginning operation.
NOTICE: When placing the battery pack
on the tool, be sure that the raised ribs on
the battery pack align with the grooves on
the tool and the latches snap into place
properly. Improper assembly of the battery
pack can cause damage to internal com-
ponents.
DETACHING BATTERY PACK
(FIG. 1)
1. Press the battery-release button to
release the battery pack.
2. Pull the battery pack to remove it from
the tool.
Page 10
BELT CLIP INSTALLATION (FIG. 2)
1. Align the rib of the belt clip with the hole
on the base of the impact wrench.
2. Insert the screw and tighten the screw
securely with a Phillips head screwdriver
(not included). The belt clip can be
positioned on either side of the tool.
BELT CLIP REMOVAL (FIG. 2)
FIG. 2
Belt Clip
Screw
1. Use a Phillips head screwdriver (not
included) to loosen the screw that
attaches the belt clip to the impact
wrench.
2. Remove the screw and the belt clip.
DIRECTION-OF-ROTATION SE-
LECTOR (FIG. 3)
FIG. 3
The direction of bit rotation is reversible and
is controlled by a selector located above the
trigger switch. With the impact wrench held
in normal operating position:
1. Position the direction-of-rotation
selector to the right of the tool for
reverse rotation to loosen bolts and
nuts.
2. Position the direction-of-rotation
selector to the left of the tool for forward
rotation to tighten bolts and nuts.
3. Setting the direction-of-rotation selector
in the off (center-lock) position helps
reduce the possibility of accidental
starting the tool when it is not in use.
NOTICE: To prevent gear damage, always
allow the impact wrench to come to a
complete stop before changing the direc-
tion of rotation.
NOTICE: The impact wrench will not run
unless the direction-of-rotation selector is
engaged fully to the left or right.
OPERATION
Page 11
OPERATION
VARIABLE-SPEED TRIGGER
SWITCH (FIG. 4)
FIG. 4
Variable-Speed
Trigger Switch
1. To turn the impact wrench on, press the
trigger switch.
2. To turn the impact wrench off, release
the trigger switch.
3. The variable-speed trigger switch
delivers higher speed with increased
trigger pressure and lower speed with
decreased trigger pressure.
SPEED CONTROL PANEL
(FIG. 5)
FIG. 5
Speed Indicator
Light
Auto Indicator
Light
AUTO
Button
LED Work
Light
Speed
Button
The impact wrench features the speed but-
ton to select among three different variable-
speed ranges. The proper setting depends
on the job, the bit type, fastener, and mate-
rial you are using.
Speed
range
No-load
speed /
RPM
Impact
rate /
IPM
Max.
fastening
torque /
ft.lb
1 0-1500 0-1900 100
2 0-2100 0-3200 150
3 0-2800 0-3800 200
Speed range 1 – the impact wrench provides
lowest speed and torque.
Speed range 2 – the impact wrench provides
medium speed and torque.
Speed range 3 – the impact wrench provides
maximum speed and torque.
The impact wrench also features the AUTO
button to turn the auto function on and off.
The auto function works differently depend-
ing on the direction of rotation of the wrench.
IN FORWARD ROTATION
1. Attach the battery pack to the impact
wrench.
2. Position the direction-of-rotation selector
to the left side of the tool for forward
rotation, and briey press the trigger
switch to turn on the speed indicator
light. The speed range will be set at “3”
without auto function.
3. Press the speed button to choose one of
the three speed ranges.
4. Press the AUTO button to use the forward
auto-stop function. When the bolt/nut is
sufciently tight, the tool automatically
stops the impact and rotation after
approximately one second. To turn off
the auto-stop function, press the AUTO
button again.
5. The speed indicator and auto indicator
lights will automatically turn off within
10-20 minutes after the trigger switch is
released.
Page 12
OPERATION
IN REVERSE ROTATION
1. Attach the battery pack to the impact
wrench.
2. Position the direction-of-rotation selector
to the right side of the tool for reverse
rotation, and briey press the trigger
switch to turn on the speed indicator
light. The speed range will be set at “3”
without auto function.
3. Press the speed button to choose one of
the three speed ranges.
4. Press the AUTO button to use the
reversal auto-slow function. When the
bolt/nut is loose, the tool automatically
decreases the rotation speed to prevent
the bolt/nut from dropping. To turn off
the auto-stop function, press the AUTO
button again.
5. The speed indicator and auto indicator
lights will automatically turn off within
10-20 minutes after the trigger switch is
released.
NOTE: The speed range will be set at “3”
without auto function each time when you
reattach the battery back.
NOTE: The 3-speed and auto functions can
be used together.
WARNING:
Watch out for the
auto and speed indicator lights before
operating the tool to reduce the risk of
injury or damage to the workpiece.
LED WORK LIGHT (FIG. 5)
The LED work light, located on the base of
the impact wrench, will illuminate when the
trigger switch is depressed before the im-
pact wrench is running. This provides addi-
tional light on the surface of the workpiece.
The light will automatically turn off within 10
seconds after the trigger switch is released.
ELECTRIC BRAKE
To stop the impact wrench, release the trig-
ger switch and allow the square drive to
come to a complete stop. The electric brake
helps to quickly stop the drive. This feature
engages automatically when you release the
trigger switch.
INSTALLING AND REMOVING
THE SOCKET (FIG. 6)
FIG. 6
Friction Ring
NOTICE: The friction ring, with certain
plasticity and strength, helps to prevent
the socket from disengaging from the out-
put driver of the impact wrench during the
operation.
NOTICE: Always use the correct size sock-
et for bolts and nuts. An incorrect socket
will result in inaccurate and inconsistent
fastening torque and/or damage to the bolt
or nut.
WARNING:
Only use sockets
designed for impact wrenches. Sockets
not designed for impact wrenches could
break and result in user injury. Inspect
sockets prior to use to ensure that they
have no cracks or other visible damage.
1. Lock the trigger switch by placing the
direction-of-rotation selector in the off
(center) position.
Page 13
2. To install the socket, push it onto the
output driver of the tool until it locks into
place.
3. To remove the socket, simply pull it off.
WARNING:
Use protective gloves
when removing the socket from the tool,
or first allow it to cool. The socket may be
hot after prolonged use.
DRIVING FASTENERS
To tighten:
1. Start threading the fastener by hand
onto or into its threaded counterpart
(e.g., nut onto bolt, or bolt into nut or
threaded hole).
2. With the proper impact socket securely
mounted to the impact wrench, slide the
impact socket onto the nut or bolt head.
3. Set the tool into forward rotation, and
activate a suitable speed range and/
or the auto-stop function. Hold the
tool rmly while depressing the trigger
switch. The impact socket will turn the
fastener and the impacting action will
begin when the fastener encounters
resistance.
To loosen:
1. With the proper impact socket securely
mounted to the wrench, slide the impact
socket onto the bolt head.
2. Set the tool into reverse position, and
select a suitable speed range and/or the
auto-slow function. Hold the tool rmly
while depressing the trigger switch. The
tool will start to impact immediately.
3. Once the fastener has “broken loose,”
it will start to unthread. Be careful that
you do not allow a fastener to spin
freely once it is no longer engaged with
its threaded counterpart, as it may be
thrown out of the socket. The auto-slow
function will help to prevent the fastener
from being thrown out of the socket.
NOTICE: Always keep the impact wrench
at a right angle to the fastener to avoid
damaging the fastener head.
OPERATION
OPERATING TIPS
The proper fastening torque may differ
depending on the type or size of the bolt, the
material of the workpiece to be fastened,
etc.
Practice with various fasteners, noting
the length of time required to reach the
desired torque. Check the tightness with
a hand-torque wrench. If the fasteners
are too tight, reduce the impacting time.
If they are not tight enough, increase the
impacting time. Hold the tool rmly, and
place the socket over the bolt or nut. Turn
the tool on, and fasten the bolt or nut to the
proper torque. The torque that is required
to loosen a fastener averages 75% to 80%
of the tightening torque, depending on
the condition of the contacting surfaces.
However, if rust or corrosion causes seizing,
more torque may be required.
After tightening, always check the torque
with a torque wrench. The tightening torque
is affected by a wide variety of factors,
including the following:
• Socket
Failure to use the correct size socket will
cause a reduction in the tightening torque.
A worn socket (wear on the hex end or the
square end) will cause a reduction in the
tightening torque.
• Bolt
Although the torque coefcient and the
class of bolt may be the same, the proper
tightening torque will differ according to the
diameter of the bolt.
Even if the diameters of bolts are the same,
the proper tightening torque will differ
according to the torque coefcient, the
class of bolt and the bolt length.
• Accessories
The use of a universal joint or an extension
bar (both available separately) will reduce
the tightening force of the impact wrench
somewhat. Compensate by tightening for a
longer period of time.
Page 14
OPERATION
MAINTENANCE
TROUBLESHOOTING
• Technique
The manner of holding the tool or the
material to be fastened will affect the torque.
NOTICE: Hold the tool straight along the
axis of the bolt or nut.
NOTICE: Excessive fastening torque may
damage the bolt/nut or socket. Before
starting your job, always perform a
test operation to determine the proper
tightening time for your bolt or nut.
BEFORE EACH USE
1. Check for damaged, missing, or worn
parts.
2. Check for loose screws, misalignment
or binding of moving parts, or any other
condition that may affect the operation.
3. If abnormal vibration or noise occurs,
turn the tool off immediately and have
the problem corrected before further
use.
WARNING:
• When servicing, use only identical
replacement parts. Use of any other
parts may create a hazard or cause
product damage.
• To avoid serious personal injury, always
remove the battery pack from the
product when cleaning or performing
any maintenance.
• Avoid using solvents when cleaning
plastic parts. Most plastics are
susceptible to damage from various
types of commercial solvents and may
be damaged by their use. Use a clean
cloth to remove dirt, dust, oil, grease,
etc.
• Using compressed air may be the most
effective cleaning method. Always
wear safety goggles when cleaning
tools with compressed air.
PROBLEM POSSIBLE CAUSE SOLUTION
The impact wrench does not
work.
The battery charge is
depleted.
Charge the battery.
The tool is overheated. Allow the tool to cool down.
The battery is overheated.
Allow the battery to cool
down.
Motor is overheating.
The cooling vents may be
obstructed.
Clean and clear the vents.
Do not cover the vents with
your hand during operation.
Page 15
NOTES
Page 16
NOTES
Page 17
NOTES
3/8’’ IMPACT WRENCH
09/2023
© 2023 Menard, Inc., Eau Claire, WI 54703
