OPERATOR'S MANUAL
7-1/4 in. (184 mm) CIRCULAR SAW
Model CSB121
DOUBLE INSULATED
THANK YOU FOR BUYING A RYOBI CIRCULAR SAW.
Your new circular saw has been engineered and manufactured to Ryobi's high standard for dependability, ease of
operation, and operator safety. Properly cared for, it will give you years of rugged, trouble-free performance.
CAUTION: Carefully read through this entire operator's manual before using your new circular saw.
Pay close attention to the Rules for Safe Operation, Warnings, and Cautions. If you use your circular saw properly
and only for what it is intended, you will enjoy years of safe, reliable service.
Thank you again for buying Ryobi tools.
SAVE THIS MANUAL FOR FUTURE REFERENCE
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GENERAL SAFETY RULES
PERSONAL SAFETY
■ Stay alert, watch what you are doing, and use
WARNING:
common sense when operating a power tool. Do
not use tool while tired or under the influence of
drugs, alcohol, or medication. A moment of inat-
tention while operating power tools may result in
serious personal injury.
Read and understand all instructions. Failure to
follow all instructions listed below, may result in
electric shock, fire and/or serious personal injury.
SAVE THESE INSTRUCTIONS
WORK AREA
■ Dress properly. Do not wear loose clothing or
jewelry. Contain long hair. Keep your hair, cloth-
ing, and gloves away from moving parts. Loose
clothes, jewelry, or long hair can be caught in mov-
ing parts.
■ Keep your work area clean and well lit. Cluttered
benches and dark areas invite accidents.
■ Do not operate power tools in explosive atmo-
spheres, such as in the presence of flammable
liquids, gases, or dust. Power tools may create
sparks which may ignite the dust or fumes.
■ Avoid accidental starting. Be sure switch is off
before plugging in. Carrying tools with your finger
on the switch or plugging in tools that have the switch
on, invites accidents.
■ Keep bystanders, children, and visitors away
while operating a power tool. Distractions can
cause you to lose control.
■ Remove adjusting keys or wrenches before turn-
ing the tool on. A wrench or a key that is left at-
tached to a rotating part of the tool may result in
personal injury.
ELECTRICAL SAFETY
■ Do not overreach. Keep proper footing and bal-
ance at all times. Proper footing and balance en-
ables better control of the tool in unexpected situa-
tions. Do not use on a ladder or unstable support.
■ Double insulated tools are equipped with a po-
larized plug (one blade is wider than the other).
This plug will fit in a polarized outlet only one
way. If the plug does not fit fully in the outlet,
reverse the plug. If it still does not fit, contact a
qualified electrician to install a polarized outlet.
Do not change the plug in any way. Double insu-
■ Use safety equipment. Always wear eye protec-
tion. Dust mask, non-skid safety shoes, hard hat, or
hearing protection must be used for appropriate con-
ditions.
lation
eliminates the need for the three-wire
grounded power cord and grounded power supply
system.
TOOL USE AND CARE
■ Use clamps or other practical way to secure and
support the workpiece to a stable platform. Hold-
ing the work by hand or against your body is un-
stable and may lead to loss of control.
■ Avoid body contact with grounded surfaces,
such as pipes, radiators, ranges, and refrigera-
tors. There is an increased risk of electric shock if
your body is grounded.
■ Do not force tool. Use the correct tool for your
application. The correct tool will do the job better
and safer at the rate for which it is designed.
■ Don’t expose power tools to rain or wet condi-
tions. Water entering a power tool will increase the
risk of electric shock.
■ Do not use tool if switch does not turn it on or
off. Any tool that cannot be controlled with the switch
is dangerous and must be repaired.
■ Do not abuse the cord. Never use the cord to
carry the tools or pull the plug from an outlet.
Keep cord away from heat, oil, sharp edges, or
moving parts. Replace damaged cords immedi-
ately. Damaged cords increase the risk of electric
shock.
■ Disconnect the plug from power source before
making any adjustments, changing accessories,
or storing the tool. Such preventive safety mea-
sures reduce the risk of starting the tool acciden-
tally.
■ When operating a power tool outside, use an
outdoor extension cord marked “W-A” or “W”.
These cords are rated for outdoor use and reduce
the risk of electric shock.
■ Store idle tools out of the reach of children and
other untrained persons. Tools are dangerous in
the hands of untrained users.
■ Maintain tools with care. Keep cutting tools sharp
and clean. Properly maintained tools with sharp
cutting edges are less likely to bind and are easier
to control.
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GENERAL SAFETY RULES
■ Check for misalignment or binding of moving
SERVICE
parts, breakage of parts, and any other condi-
tion that may affect the tool’s operation. If dam-
aged, have the tool serviced before using. Many
accidents are caused by poorly maintained tools.
■ Tool service must be performed only by quali-
fied repair personnel. Service or maintenance per-
formed by unqualified personnel could result in a risk
of injury.
■ Use only accessories that are recommended by
the manufacturer for your model. Accessories that
may be suitable for one tool, may become hazard-
ous when used on another tool.
■ When servicing a tool, use only identical replace-
ment parts. Follow instructions in the Mainte-
nance section of this manual. Use of unauthorized
parts or failure to follow Maintenance Instructions
may create a risk of electric shock or injury.
SPECIFIC SAFETY RULES
■ NEVER hold piece being cut in your hands or
across your leg. It is important to support the work
properly to minimize body exposure, blade binding,
or loss of control.
■ DANGER! Keep hands away from cutting area
and blade. Keep your second hand on the
auxiliary handle or motor housing. If both hands
are holding the saw, they cannot be cut by the blade.
■ Hold tool by insulated gripping surface when
performing an operation where the cutting tool
maycontacthiddenwiringoritsowncord.Contact
with a “live” wire will also make exposed metal parts
of the tool “live” and shock the operator.
■ Keep your body positioned to either side of the
saw blade, but not in line with the saw blade.
Kickback could cause the saw to jump backwards.
(Refer to “CAUSES AND OPERATOR
PREVENTION OF KICKBACK” later.)
■ When ripping, always use a rip fence or straight
edge guide. This improves the accuracy of the cut
and reduces the chance for blade binding.
■ Do not reach underneath the work. The guard
cannot protect you from the blade below the work.
■ Check lower guard for proper closing before
eachuse.Donotoperatesawiflowerguarddoes
notmovefreelyandcloseinstantly. Neverclamp
or tie the lower guard into the open position. If
saw is accidentally dropped, lower guard may be
bent. Raise the lower guard with the retracting
handle. Make sure it moves freely and does not
touch the blade or any other part, in all angles and
depths of cut.
■ Always use blades with correct size and shape
(diamond vs. round) arbor holes. Blades that do
not match the mounting hardware of the saw will run
eccentrically, causing loss of control.
■ Never use damaged or incorrect blade washers
orbolts.Thebladewashersandboltswerespecially
designedforyoursawforoptimumperformanceand
safety of operation.
■ Check the operation and condition of the lower
guard spring. If the guard and the spring are not
operatingproperly,theymustbeservicedbefore
use. Lower guard may operate sluggishly due to
damaged parts, gummy deposits, or a buildup of
debris.
CAUSES AND OPERATOR PREVENTION
OF KICKBACK
Kickback is a sudden reaction to a pinched, bound, or
misalignedsawblade,causinganuncontrolledsawtolift
up and out of the workpiece toward the operator.
■ Lower guard should be retracted manually only
for special cuts, such as "Pocket Cuts" and
"Compound Cuts." Raise lower guard by
retracting handle. As soon as blade enters the
material, lower guard must be released. For all
other sawing, the lower guard should operate
automatically.
When the blade is pinched or bound tightly by the kerf
closing down, the blade stalls and the motor reaction
drives the unit rapidly back toward the operator.
If the blade becomes twisted or misaligned in the cut, the
teeth at the back edge of the blade can dig into the top
surface of the wood causing the blade to climb out of the
kerf and jump back toward the operator.
■ Always observe that the lower guard is covering
the blade before placing saw down on bench or
floor. An unprotected, coasting blade will cause the
saw to walk backwards, cutting whatever is in its
path. Be aware of the time it takes for the blade to
stop after switch is released.
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SPECIFIC SAFETY RULES
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:
■ Support large panels to minimize the risk of
blade pinching and KICKBACK. Large panels
tend to sag under their own weight. Supports must
be placed under the panel on both sides, near the
line of cut and near the edge of the panel.
■ Maintain a firm grip with both hands on the saw
and position your body and arm to allow you to
resist KICKBACK forces. KICKBACK forces can
be controlled by the operator, if proper precautions
are taken.
■ Do not use dull or damaged blade. Unsharpened
or improperly set blades produce narrow kerf which
causes excessive friction, blade binding and
KICKBACK.
■ When blade is binding, or when interrupting a
cut for any reason, release the trigger and hold
thesawmotionlessinthematerialuntiltheblade
comes to a complete stop. Never attempt to
remove the saw from the work or pull the saw
backward while the blade is in motion, or
KICKBACK may occur. Investigate and take
corrective actions to eliminate the cause of blade
binding.
■ Blade depth and bevel adjusting locking levers
must be tight and secure before making cut. If
blade adjustment shifts while cutting, it may cause
binding and KICKBACK.
■ Use extra caution when making a “Pocket Cut”
into existing walls or other blind areas. The
protruding blade may cut objects that can cause
KICKBACK.
■ When restarting a saw in the workpiece, center
the saw blade in the kerf and check that saw
teeth are not engaged into the material. If saw
blade is binding, it may walk up or KICKBACK from
the workpiece as the saw is restarted.
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ADDITIONAL SAFETY RULES
Hold tool by insulated gripping surfaces when performing an operation where the cutting tool may con-
tact hidden wiring or its cord. Contact with a “live” wire will make exposed metal parts of the tool “live” and
shock the operator.
■ Know your power tool. Read operator’s manual
carefully. Learn its applications and limitations,
as well as the specific potential hazards related
to this tool. Following this rule will reduce the risk
of electric shock, fire, or serious injury.
■ Inspect for and remove all nails from lumber be-
fore sawing. Following this rule will reduce the risk
of serious personal injury.
■ Drugs, alcohol, medication. Do not operate tool
while under the influence of drugs, alcohol, or
any medication. Following this rule will reduce the
risk of electric shock, fire, or serious personal injury.
■ Always wear safety glasses. Everyday eye-
glasses have only impact-resistant lenses; they
are NOT safety glasses. Following this rule will re-
duce the risk of serious personal injury.
■ Save these instructions. Refer to them frequently
and use them to instruct others who may use
this tool. If you loan someone this tool, loan them
these instructions also.
■ Protect your lungs. Wear a face or dust mask if
the operation is dusty. Following this rule will re-
duce the risk of serious personal injury.
■ Protect your hearing. Wear hearing protection
during extended periods of operation. Following
this rule will reduce the risk of serious personal in-
jury.
WARNING:
Some dust created by power sanding, sawing,
grinding, drilling, and other construction activities
contains chemicals known to cause cancer, birth
defects or other reproductive harm. Some examples
of these chemicals are:
■ Inspect tool cords periodically and, if damaged,
have repaired at your nearest Factory Service
Center or otherAuthorized Service Organization.
Constantly stay aware of cord location. Follow-
ing this rule will reduce the risk of electric shock or
fire.
• lead from lead-based paints,
• crystalline silica from bricks and cement
and other masonry products, and
■ Check damaged parts. Before further use of the
tool, a guard or other part that is damaged should
be carefully checked to determine that it will
operate properly and perform its intended func-
tion. Check for alignment of moving parts, bind-
ing of moving parts, breakage of parts, mount-
ing, and any other conditions that may affect its
operation. A guard or other part that is damaged
should be properly repaired or replaced by an
authorized service center. Following this rule will
reduce the risk of shock, fire, or serious injury.
• 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: 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.
■ Do not abuse cord. Never carry the tool by the
cord or yank it to disconnect it from the recep-
tacle. Keep cord away from heat, oil, and sharp
edges. Following this rule will reduce the risk of elec-
tric shock or fire.
■ Make sure your extension cord is in good condi-
tion. When using an extension cord, be sure to
use one heavy enough to carry the current your
product will draw. A wire gage size (A.W.G.) of at
least 14 is recommended for an extension cord
50 feet or less in length. A cord exceeding 100
feet is not recommended. If in doubt, use the next
heavier gage. The smaller the gage number, the
heavier the cord. An undersized cord will cause a
drop in line voltage resulting in loss of power and
overheating.
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SYMBOLS
Important: Some of the following symbols may be used on your tool. Please study them and learn their meaning.
Proper interpretation of these symbols will allow you to operate the tool better and safer.
SYMBOL
NAME
DESIGNATION/EXPLANATION
V
Volts
Voltage
A
Hz
W
Amperes
Hertz
Current
Frequency (cycles per second)
Watt
Power
min
Minutes
Time
Alternating Current
Type or a characteristic of current
n
No Load Speed
Rotational speed, at no load
0
Class II Construction
Designates double-insulated
construction tools
.../min
Revolutions or Reciprocation Per Minute
Safety Alert
Revolutions, strokes, surface speed,
orbits etc. per minute
Indicates danger, warning or caution.
It means attention!!! Your safety is
involved.
Wet Conditions Alert
Do not expose to rain or use in damp
locations.
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 understanding. The safety warnings do not by
themselves eliminate any danger. The instructions or warnings they give are not substitutes for proper accident
prevention measures.
SYMBOL MEANING
DANGER:Failuretoobeyasafetywarningwillresultinseriousinjurytoyourselfortoothers. Always
follow the safety precautions to reduce the risk of fire, electric shock and personal injury.
WARNING: Failure to obey a safety warning can result in serious injury to yourself or to others.
Always follow the safety precautions to reduce the risk of fire, electric shock and personal injury.
CAUTION: Failure to obey a safety warning may result in property damage or personal injury to
yourself or to others. Always follow the safety precautions to reduce the risk of fire, electric shock and
personal injury.
NOTE: Advises you of information or instructions vital to the operation or maintenance of the equipment.
SAVE THESE INSTRUCTIONS
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SPECIFICATIONS
Blade Diameter
Blade Arbor
7-1/4 in. (184 mm)
5/8 in. (16 mm)
2-3/8 in. (60 mm)
1-13/16 in. (46 mm)
1-5/8 in. (41 mm)
120 volts, 60 Hz, AC
12 amperes
Cutting Depth at 0°
Cutting Depth at 45°
Cutting Depth at 51.5°
Rating
Input
No Load Speed
Net Weight
4600 RPM
11 lbs. (5 kg)
UNPACKING
INSTRUCTIONS
PACKING LIST
Your circular saw has been shipped completely
assembled.
Circular Saw
7-1/4 in. (184 mm) Blade
Case
■ Carefully remove the tool and accessories from the
box. Make sure that all items listed in the packing
list are included.
Wrench
Warranty Card
Operator's Manual
■ Inspect the tool carefully to make sure no
breakage or damage has occurred during
shipping.
WARNING:
■ Do not discard the packing material until you have
carefully inspected and satisfactorily operated the
tool.
If any parts are missing, do not operate this tool until
the missing parts are replaced. Failure to do so could
result in possible serious personal injury.
■ If any parts are damaged or missing, please
contact Ryobi Customer Service. Refer to the back
page of this manual for contact information.
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FEATURES
DOUBLE INSULATION
SWITCH
Your Ryobi power tool is double insulated. This means
you are separated from the tool's electrical system by
two complete sets of electrical insulation. This extra
layer of insulation is intended to protect the user from
electricalshockduetoabreakinthewiringinsulation. All
exposed metal parts are isolated from the internal metal
motor components with protecting insulation. Double
insulated tools do not need to be grounded.
Your circular saw is equipped with a pre-travel safety
switchwhichreducesthepossibilityofaccidentalstarting.
When you depress the switch, the saw will not start until
you reach the pre-travel position. You must depress the
switch fully to activate the saw.
SPINDLE LOCK
The spindle lock allows you to secure the blade when
turning the blade screw.
NOTE:Donotruncircularsawwithspindlelockengaged.
WARNING:
The double insulated system is intended to protect
the user from shock resulting from a break in the tool's
internal wiring. Observe all normal safety precautions
related to avoiding electrical shock.
WRENCH STORAGE
The circular saw is equipped with a wrench storage area
in the base of the tool.
ERGONOMIC DESIGN
Important: Servicing of a tool with double insulation
requires extreme care and knowledge of the system and
should be performed only by a qualified service
technician. For service we suggest you return the tool to
yournearestRYOBIAUTHORIZEDSERVICECENTER
for repair. When servicing use only identical Ryobi
replacement parts.
Thedesignofyourcircularsawprovidesforeasyhandling
and maintaining proper two hand control when cutting. It
has been designed to be comfortable and easy to grasp
when operating in different positions or at different
angles.
ELECTRIC MOTOR
Your circular saw has a precision-built electric motor. It
should be connected to a power supply that is 120
volts, 60 Hz only. Do not operate this tool on direct
current(DC). Asubstantialvoltagedropwillcausealoss
of power and the motor will overheat. If your saw does
not operate when plugged into an outlet, double-check
the power supply.
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FEATURES
DEPTH
ADJUSTMENT
WING NUT
SWITCH
UPPER
BLADE
GUARD
BLADE
WRENCH STORAGE
AREA
WRENCH
LOWER
BLADE
GUARD
BASE
SPINDLE LOCK
BUTTON
HANDLE
LOWER BLADE
GUARD HANDLE
MOTOR
HOUSING
BEVEL CUT
ADJUSTMENT
WING NUT
Fig. 1
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 personal
injury.
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ASSEMBLY
WARNING:
SPINDLE
Your tool should never be connected to power supply
when you are assembling parts, making adjustments,
cleaning, performing maintenance, or when not in
use. Disconnecting your tool will prevent accidental
starting that could cause serious injury.
BLADE
OUTER
WASHER
(“D”
WASHER)
WARNING:
7-1/4 in. (184 mm) blade is the maximum blade
capacity of your saw. Also, never use a blade that is
too thick to allow outer blade washer to engage with
the flat on the spindle. Larger blades will come in
contact with the blade guards, while thicker blades
will prevent blade screw from securing blade on
spindle. Either of these situations could result in a
serious accident.
INNER
WASHER
BLADE
SPRING SCREW
WASHER
Fig. 2
■ Fit saw blade inside lower blade guard and onto
spindle.
ATTACHING BLADE
NOTE: The saw teeth point upward at the front of
the saw as shown.
See Figures 2 and 3.
Follow these directions to attach the blade.
■ UNPLUG YOUR CIRCULAR SAW.
■ Replace “D” washer and spring washer.
NOTE: "Cupped" side of spring washer goes against
“D” washer.
WARNING:
Failure to unplug the tool could result in accidental
starting causing serious injury.
OUTER WASHER
(“D” WASHER)
■ Remove wrench from storage area.
CAUTION:
To prevent damage to the spindle or spindle lock,
always allow motor to come to a complete stop before
engaging spindle lock.
CUPPED SIDE OF OUTSIDE OF SPRING
SPRING WASHER
WASHER
■ Depress spindle lock button.
Fig. 3
■ Remove blade screw by turning it counterclockwise
with the wrench.
■ Remove spring washer and outer washer
■ Depress spindle lock and replace blade screw.
(“D” washer).
■ Tighten blade screw securely by turning it clockwise
■ Wipe a drop of oil onto inner washer and outer
with the wrench.
washer ("D" washer) where they contact blade.
■ Return wrench to storage area.
NOTE: Never use a blade that is too thick to allow
the "D" washer to engage with the flat on the spindle.
WARNING:
If inner washer has been removed, replace it before
placing blade on spindle. Failure to do so could cause
an accident since blade will not tighten properly.
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ASSEMBLY
REMOVING BLADE
SPINDLE
LOCK
BUTTON
See Figure 4.
Follow these directions to remove the blade.
■ UNPLUG YOUR CIRCULAR SAW.
WARNING:
Failure to unplug the tool could result in accidental
starting causing serious injury.
■ Remove wrench from storage area.
CAUTION:
BLADE
SCREW
To prevent damage to the spindle or spindle lock,
always allow motor to come to a complete stop before
engaging spindle lock.
WRENCH
Fig. 4
■ Depress spindle lock button.
■ Remove blade screw by turning it counterclockwise
■ Lift lower blade guard.
■ Remove blade.
with the wrench.
■ Remove spring washer and outer blade washer ("D"
■ Return wrench to storage area.
washer).
OPERATION
SAW BLADES
CAUTION:
The best of saw blades will not cut efficiently if they are
not kept clean, sharp, and properly set. Using a dull
blade will place a heavy load on your saw and increase
the danger of kickback. Keep extra blades on hand, so
that sharp blades are always available.
Never use saw when guard is not operating correctly.
Check the guard for correct operation before each
use. The guard is operating correctly when it moves
freely and readily returns to the closed position. If
you drop the saw, check the lower blade guard and
bumper for damage at all depth settings before reuse.
Gum and wood pitch hardened on blades will slow your
saw down. Remove saw blade from your saw and use
gum and pitch remover, hot water, or kerosene to
removetheseaccumulations.DONOTUSEGASOLINE.
BLADE GUARD SYSTEM
See Figure 5.
The lower blade guard attached to your circular saw is
thereforyourprotectionandsafety. Donotalteritforany
reason. If it becomes damaged, do not operate the saw
until you have the guard repaired or replaced. Always
leave guard in operating position when using the saw.
DANGER:
When sawing through work, lower blade guard does
not cover blade on the underside of work. Since blade
is exposed on underside of work, keep hands and
fingers away from cutting area. Any part of your body
coming in contact with moving blade will result in
serious injury.
LOWER BLADE GUARD
IS IN UP POSITION
WHEN MAKING A CUT
Fig. 5
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OPERATION
KICKBACK
See Figure 6, 7, 8, and 9.
Kickback occurs when the blade stalls rapidly and the
saw is driven back towards you. Blade stalling is caused
by any action which pinches the blade in the wood.
DANGER:
Release switch immediately if blade binds or saw
stalls. Kickback could cause you to lose control of
your saw. Loss of control can lead to serious injury.
KICKBACK - BLADE SET TOO DEEP
Fig. 6
To guard against kickback, avoid dangerous practices
such as the following.
INCORRECT
SUPPORT
■ Setting blade depth incorrectly.
■ Sawing into knots or nails in workpiece.
■ Twisting the blade while making a cut.
■ Making a cut with a dull, gummed up, or improperly
set blade.
■ Supporting the workpiece incorrectly.
■ Forcing a cut.
■ Cutting warped or wet lumber.
■ Operating the tool incorrectly or misusing the tool.
To lesson the chance of kickback, follow these safety
practices.
Fig. 7
■ Keep the blade at the correct depth setting. The
depth setting should not exceed 1/4 in. (6.35 mm)
below the material being cut.
■ Inspect the workpiece for knots or nails before cut-
ting. Never saw into a knot or nail.
■ Make straight cuts. Always use a straight edge guide
when rip cutting. This helps prevent twisting the
blade.
■ Use clean, sharp, and properly set blades. Never
make cuts with dull blades.
■ Support the workpiece properly before beginning a
CORRECT BLADE DEPTH SETTING = BLADE
EXPOSED 1/4 in. (6.35 mm) OR LESS ON
UNDERSIDE OF WORKPIECE
cut.
■ Use steady, even pressure when making a cut. Never
force a cut.
Fig. 8
■ Do not cut warped or wet lumber.
CORRECT
SUPPORT
■ Hold the saw firmly with both hands and keep your
body in a balanced position so as to resist the forces
if kickback should occur.
WARNING:
When using your saw, always stay alert and exercise
control. Do not remove your saw from the workpiece
while the blade is moving.
Fig. 9
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OPERATION
STARTING/STOPPING THE SAW
See Figure 10.
SWITCH
To start the saw: Depress the switch trigger.
Always let the blade reach full speed, then guide the saw
into the workpiece.
WARNING:
The blade coming in contact with the workpiece
before it reaches full speed could cause your saw to
“kickback” towards you resulting in serious injury.
Fig. 10
To stop the saw: Release the switch trigger.
After you release the switch trigger, allow the blade to
come to a complete stop. Do not remove the saw from
the workpiece while the blade is moving.
DEPTH OF CUT
SCALE
ADJUSTING BLADE DEPTH
See Figure 11.
Always keep correct blade depth setting. The correct
blade depth setting for all cuts should not exceed 1/4 in.
(6.35 mm) below the material being cut. More blade
depthwillincreasethechanceofkickbackandcausethe
cut to be rough. For more depth of cut accuracy, a scale
is located on the upper blade guard.
Follow these directions to adjust the blade depth.
■ UNPLUG YOUR CIRCULAR SAW.
WING NUT
BASE
Fig. 11
WARNING:
Failure to unplug the tool could result in accidental
starting causing serious injury.
■ Loosen wing nut on back of saw.
■ Determine the desired depth of cut.
■ Locate depth of cut scale on back of upper blade
guard.
■ Hold base flat against the workpiece and raise or
lower saw until the indicator mark on bracket aligns
with notch on blade guard.
■ Tighten wing nut securely.
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OPERATION
OPERATING THE SAW
See Figures 12, 13, and 14.
It is important to understand the correct method for
operating your saw. Refer to the figures in this section to
learn the correct and incorrect ways for handling your
saw.
WARNING:
To make sawing easier and safer, always maintain
proper control of the saw. Loss of control could cause
an accident resulting in possible serious injury.
DANGER:
When lifting your saw from the workpiece, the blade
is exposed on the underside of the saw until the lower
blade guard closes. Make sure the lower blade guard
is closed before setting your saw down.
Fig. 12
To make the best possible cut, follow these helpful hints.
■ Hold the saw firmly with both hands.
■ Avoid placing your hand on the workpiece while
making a cut.
■ Support the workpiece with a clamp near the cut.
■ Clamp the workpiece securely so that the workpiece
will not move during the cut.
■ Support the workpiece so that the cut is always on
your right.
■ Avoid placing the saw on the part of the workpiece
that will fall off when the cut is made.
■ Place the workpiece with the “good” side down.
■ Draw a guideline along the desired line of cut before
Fig. 13
beginning your cut.
■ Keep the cord away from the cutting area. Always
place the cord to prevent it from hanging up on the
workpiece while making a cut.
DANGER:
If the cord hangs up on the workpiece during a cut,
release the switch trigger immediately. Unplug the
saw and reposition the cord to prevent it from hanging
up again.
DANGER:
Using a saw with a damaged cord could result in
serious injury or death. If the cord has been damaged,
have it replaced before using the saw again.
Fig. 14
15
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OPERATION
CROSS CUTTING/RIP CUTTING
See Figure 15.
TOP VIEW OF SAW
When making a cross cut or rip cut, align the line of cut
with the outer blade guide notch on the base as shown
in the figure.
Since blade thicknesses vary, always make a trial cut in
scrapmaterialalongaguidelinetodeterminehowmuch,
if any, you must offset the guideline to produce an
accurate cut.
BLADE
GUIDE
NOTCH
NOTE: The distance from the line of cut to the guideline
is the amount you should offset the guideline.
TO RIP CUT
See Figure 16.
Use a guide when making long or wide rip cuts with your
saw.
GUIDELINE
NOTE: You may also use a rip guide to make rip cuts.
Fig. 15
Refer to “OPTIONAL RIP GUIDE” later in this manual.
Follow these directions to rip cut.
STRAIGHT
EDGE
■ Secure the workpiece.
■ Clamp a straight edge to the workpiece using
C-clamps.
■ Saw along the straight edge to achieve a straight rip
cut.
NOTE: Do not bind the blade in the cut.
C-CLAMPS
WORKPIECE
Fig. 16
16
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OPERATION
BEVEL CUTTING
See Figures 17 and 18.
MOTOR
HOUSING
To make the best possible cut, follow these helpful hints.
■ Align the line of cut with the inner blade guide notch
on the base when making 45° bevel cuts.
■ Make a trial cut in scrap material along a guideline to
determine how much you should offset the guideline
on the cutting material.
■ Adjust the angle of the cut to any desired setting
between zero and 51.5°. Refer to “TO ADJUST
BEVEL SETTING” next.
BEVEL SCALE
WING
NUT
TO ADJUST BEVEL SETTING
See Figure 17.
Follow these directions to adjust the bevel setting.
■ UNPLUG YOUR CIRCULAR SAW.
WARNING:
BLADE GUIDE NOTCH
Failure to unplug the tool could result in accidental
starting causing serious injury.
Fig. 17
■ Loosen wing nut.
■ Raise motor housing end of saw until you reach
desired angle setting on bevel scale.
■ Tighten wing nut securely.
WARNING:
Attempting a bevel cut without having the wing nut
securely tightened can result in serious injury.
TO BEVEL CUT
See Figure 18.
Follow these directions to bevel cut.
■ Hold the saw firmly with both hands as shown.
■ Rest the front edge of the base on the workpiece.
■ Start the saw and let the blade reach full speed.
■ Guide the saw into the workpiece and make the cut.
Fig. 18
■ Release the trigger and allow the blade to come to a
complete stop.
■ Lift the saw from the workpiece.
17
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OPERATION
POSITIVE 0° BEVEL STOP
See Figure 19.
Your saw has a positive 0° bevel stop, that has been
factory adjusted to assure 0° angle of the saw blade
when making 90° cuts. However, misalignment can
occur during shipping.
HEX NUT
TO CHECK POSITIVE 0° BEVEL STOP
Follow these directions to check the positive 0° bevel
stop.
WING NUT
■ UNPLUG YOUR CIRCULAR SAW.
CARPENTER’S
SQUARE
WARNING:
Failure to unplug the tool could result in accidental
starting causing serious injury.
■ Place the saw in an upside down position on a
workbench.
■ Check the squareness of the saw blade to the base
of the saw using a carpenter’s square.
TO ADJUST POSITIVE 0° BEVEL STOP
Follow these directions to adjust the positive 0° bevel
stop.
■ UNPLUG YOUR CIRCULAR SAW.
WARNING:
Fig. 19
Failure to unplug the tool could result in accidental
starting causing serious injury.
■ Loosen wing nut.
■ Loosen hex nut securing adjusting screw.
■ Turn screw and adjust base until square with saw
blade.
■ Tighten hex nut and wing nut securely.
WARNING:
Attempting a bevel cut without having the wing nut
securely tightened can result in serious injury.
LENGTH OF CUT SCALE
See Figure 20.
LENGTH OF CUT SCALE
Your saw is equipped with a length of cut scale on its
base. It is parallel with the saw blade and you can use it
to measure the distance into the material the blade cuts.
Fig. 20
NOTE: Six inches is the maximum length of cut that you
can measure. Also, it is accurate only when the depth of
cut is set at full maximum depth.
18
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OPERATION
POCKET CUTTING
See Figure 21.
WARNING:
LOWER
BLADE
GUARD
Always adjust bevel setting to zero before making a
pocket cut. Attempting a pocket cut at any other
setting can result in loss of control of your saw
possibly causing serious injury.
Follow these directions to pocket cut.
■ Adjust the bevel setting to zero.
■ Set the blade to the correct blade depth setting.
■ Swing the lower blade guard up using the lower blade
LOWER BLADE
GUARD HANDLE
guard handle.
NOTE: Always raise the lower blade guard with the
handle to avoid serious injury.
POCKET
CUT
■ Hold the lower blade guard by the handle.
Fig. 21
■ Rest the front of the base flat against the workpiece
with the rear of the handle raised so the blade does
not touch the workpiece.
■ Start the saw and let the blade reach full speed.
■ Guide the saw into the workpiece and make the cut.
WARNING:
Always cut in a forward direction when pocket cutting.
Cutting in the reverse direction could cause the saw
to climb up on the workpiece and back toward you.
■ Release the trigger and allow the blade to come to a
complete stop.
■ Lift the saw from the workpiece.
■ Clear corners out with a hand saw or sabre saw.
WARNING:
Never tie the lower blade guard in a raised position.
Leaving the blade exposed could lead to serious
injury.
19
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ACCESSORIES
OPTIONAL RIP GUIDE
Use the optional rip guide, part no. 969862-009, when
making long or wide rip cuts with your saw.
TO ASSEMBLE RIP GUIDE
See Figure 22.
Follow these directions to assemble the rip guide.
■ UNPLUG YOUR CIRCULAR SAW.
WARNING:
RIP GUIDE
SCREW
Failure to unplug the tool could result in accidental
starting causing serious injury.
■ Place rip guide through holes in base as shown in the
figure.
RIP GUIDE
■ Adjust rip guide to the width needed.
■ Tighten rip guide knob securely.
TO USE RIP GUIDE
Follow these directions to use the rip guide.
■ Secure the workpiece.
Fig. 22
■ Position the face of the rip guide firmly against the
edge of workpiece.
■ Guidethesawalongtheedgetoachieveastraightrip
cut.
NOTE: The guiding edge of the workpiece must be
straight for your cut to be straight. Use caution to
prevent the blade from binding in the cut.
ADAPTER
OPTIONAL DUST NOZZLE KIT
See Figure 23.
HOLE
You may purchase a dust nozzle kit, part no. 982829-
001, for use with your saw. As shown in the figure, the
adapter fits over the dust chute which is located on the
upper blade guard.The nozzle attaches to the adapter.
DUST
CHUTE
SCREW
NOTE:Ifyouusethenozzle, youshouldalwaysconnect
it to a standard vacuum hose.
RAISED
LIP
NOZZLE
TO ATTACH DUST NOZZLE
Follow these directions to attach the dust nozzle.
Fig. 23
■ UNPLUG YOUR CIRCULAR SAW.
WARNING:
Failure to unplug the tool could result in accidental
starting causing serious injury.
■ Lift lower blade guard.
■ Orient adapter to fit into the dust chute opening (1) on
upper blade guard.
■ Secure adapter with screw (2) provided.
■ Align hole in nozzle with raised lip on adapter and
snap into place (3) when using a vacuum hose.
20
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MAINTENANCE
WARNING:
When servicing use only identical Ryobi replacement parts. Use of any other parts may create a hazard or
cause product damage.
GENERAL
LUBRICATION
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 clean cloths to remove dirt, carbon dust, etc.
All of the bearings in this tool are lubricated with a
sufficient amount of high grade lubricant for the life of the
unit under normal operating conditions. Therefore, no
further lubrication is required.
WARNING:
Do not at any time let brake fluids, gasoline,
petroleum-based products, penetrating oils, etc.
come in contact with plastic parts. They contain
chemicals that can damage, weaken, or destroy
plastic.
When electric tools are used on fiberglass boats, sports
cars, wallboard, spackling compounds, or plaster, it has
beenfoundthattheyaresubjecttoacceleratedwearand
possible premature failure, as the fiberglass chips and
grindings are highly abrasive to bearings, brushes,
commutators, etc. Consequently, it is not recommended
thatthistoolbeusedforextendedworkonanyfiberglass
material, wallboard, spackling compounds, or plaster. If,
however, you do work with any of these materials, it is
extremelyimportantthatthetooliscleanedfrequentlyby
blowing with an air jet.
WARNING:
Always wear safety goggles or safety glasses with
side shields during power tool operation or when
blowing dust. If operation is dusty, also wear a dust
mask.
21
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OPERATOR'S MANUAL
7-1/4 in. (184.15 mm) CIRCULAR SAW
Model CSB121
DOUBLE INSULATED
**Ampere rating
EXTENSION CORD CAUTION
(on tool faceplate)
0-2.0
2.1-3.4
3.5-5.0
5.1-7.0
7.1-12.0 12.1-16.0
When using a power tool at a considerable distance from a
power source, be sure to use an extension cord that has the
capacity to handle the current the tool will draw. An under-
sized cord will cause a drop in line voltage, resulting in over-
heating and loss of power. Use the chart to determine the mini-
mum wire size required in an extension cord. Only round jack-
eted cords should be used.
Cord Length
Wire Size (A.W.G.)
25'
50'
16
16
16
16
16
16
16
16
14
16
14
12
14
14
10
14
12
—
100'
When working with a tool outdoors, use an extension cord
that is designed for outside use. This is indicated by the letters
"WA" on the cord's jacket.
CAUTION: Keep the extension cord clear of the working
area. Position the cord so that it will not get caught on
lumber, tools or other obstructions while you are working
with a power tool.
Before using any extension cord, inspect it for loose or ex-
posed wires and cut or worn insulation.
**Used on 12 gauge - 20 amp circuit.
• SERVICE
Now that you have purchased your tool, should a need ever exist for repair parts or
service, simply contact your nearest Ryobi Authorized Service Center. Be sure to
provide all pertinent facts when you call or visit. Please call 1-800-525-2579 for your
nearest Ryobi Authorized Service Center. You can also check our Web site at
• MODEL NO. AND SERIAL NO.
The model number of this tool will be found on a plate attached to the motor housing.
Please record the model number and serial number in the space provided below.
• HOW TO ORDER REPAIR PARTS
WHEN ORDERING REPAIR PARTS,
ALWAYS GIVE THE FOLLOWING INFORMATION:
CSB121
• MODEL NUMBER
• SERIAL NUMBER
RYOBI TECHNOLOGIES INC.
1428 Pearman Dairy Road
Anderson, SC 29625
Post Office Box 1207
Anderson, SC 29622
Phone 1-800-525-2579
983000-126
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