makita GA5051R Angle Grinder Instruction Manual

: June 4, 2024
: Makita

Table of Contents

SPECIFICATIONS
SAFETY WARNINGS
FUNCTIONAL DESCRIPTION
ASSEMBLY
OPERATION
MAINTENANCE
OPTIONAL ACCESSORIES
Documents / Resources

Angle Grinder
INSTRUCTION MANUAL
GA4051R, GA4551R, GA5051R makita GA5051R Angle
Grinder makita GA5051R Angle Grinder - fig makita GA5051R
Angle Grinder - fig 1

SPECIFICATIONS

Model:| GA4051R| GA4551R|

GA5051R

---|---|---|---
Wheel diameter| 100 mm (4″)| 115 mm (4-1/2″)| 125 mm (5″)
Max. wheel thickness| 6.4 mm (1/4″)| 7.2 mm (9/32″)
Spindle thread| M10| M14 or 5/8″
Rated speed (n)| 11,000 min-1
Overall length| 325 mm
Net weight| 2.3 – 2.5 kg| 2.5 – 2.7 kg
Safety class| /II

Due to our continuing program of research and development, the specifications herein are subject to change without notice.
Specifications may differ from country to country.
The weight may differ depending on the attachment(s). The lightest and heaviest combinations, according to EPTA-Procedure 01/2014, are shown in the table.

Intended use
The tool is intended for grinding without the use of water.
Power supply
The tool should be connected only to a power supply of the same voltage as indicated on the nameplate, and can only be operated on a single-phase AC supply. They are double-insulated and can, therefore, also be used from sockets without earth wire.
Noise
The typical A-weighted noise level determined according to EN60745-2-3:

Model| Sound pressure level (L pA ) **: ****(dB(A))| Sound power level (L WA ) : (dB(A))| Uncertainty (K) : (dB(A))**
---|---|---|---
GA4051R| 91| 102| 3
GA4551R| 91| 102| 3
GA5051R| 91| 102| 3

NOTE: The declared noise emission value(s) has been measured in accordance with a standard test method and may be used for comparing one tool with another.
NOTE: The declared noise emission value(s) may also be used in a preliminary assessment of exposure.
WARNING: Wear ear protection.
WARNING: The noise emission during actual use of the power tool can differ from the declared value(s) depending on the ways in which the tool is used especially what kind of workpiece is processed.
WARNING: Be sure to identify safety measures to protect the operator that is based on an estimation of exposure in the actual conditions of use (taking account of all parts of the operating cycle such as the times when the tool is switched off and when it is running idle in addition to the trigger time).
Vibration
The vibration total value (tri-axial vector sum) determined according to EN60745-2-3:
Work mode: surface grinding with normal side grip

Model| Vibration emission (a h , AG ) : (m/s 2 )| Uncertainty (K) : (m/s 2)
---|---|---
GA4051R| 6.5| 1.5
GA4551R| 7.0| 1.5
GA5051R| 7.5| 1.5

Work mode: surface grinding with anti-vibration side grip

Model| Vibration emission (a h , AG ) : (m/s 2 )| Uncertainty (K) : (m/s 2)
---|---|---
GA4051R| 5.5| 1.5
GA4551R| 7.0| 1.5
GA5051R| 8.5| 1.5

Work mode: disc sanding with normal side grip

Model| Vibration emission (a h , AG ) : (m/s 2 )| Uncertainty (K) : (m/s 2)
---|---|---
GA4051R| 2.5 m/s2 or less| 1.5
GA4551R| 2.5| 1.5
GA5051R| 2.5 m/s2 or less| 1.5

Work mode: disc sanding with anti-vibration side grip

Model| Vibration emission (a h , AG ) : (m/s 2 )| Uncertainty (K) : (m/s 2)
---|---|---
GA4051R| 2.5 m/s2 or less| 1.5
GA4551R| 2.5 m/s2 or less| 1.5
GA5051R| 2.5 m/s2 or less| 1.5

NOTE: The declared vibration total value(s) has been measured in accordance with a standard test method and may be used for comparing one tool with another.
NOTE: The declared vibration total value(s) may also be used in a preliminary assessment of exposure.
WARNING: The vibration emission during actual use of the power tool can differ from the declared value(s) depending on the ways in which the tool is used especially what kind of workpiece is processed.
WARNING: Be sure to identify safety measures to protect the operator that is based on an estimation of exposure in the actual conditions of use (taking account of all parts of the operating cycle such as the times when the tool is switched off and when it is running idle in addition to the trigger time).
WARNING: The declared vibration emission value is used for the main applications of the power tool. However, if the power tool is used for other applications, the vibration emission value may be different.
EC Declaration of Conformity
For European countries only
The EC declaration of conformity is included as Annex A to this instruction manual.

SAFETY WARNINGS

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, 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.
Grinder safety warnings
Safety Warnings Common for Grinding, Wire Brushing Operations:

This power tool is intended to function as a grinder or wire brush. 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.
Operations such as polishing, sanding, and cutting-off are 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.
Do not use accessories that 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.
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.
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.
The 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 a loss of control.
Do not use a damaged accessory. Before each use inspects the accessory such as the wire brush for loose or cracked wires. If a 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.
Wear personal protective equipment. Depending on the application, use a face shield, safety goggles, or safety glasses. As appropriate, wear a dust mask, hearing protectors, gloves, and a 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.
Keep bystanders a safe distance away from the work area. Anyone entering the work area must wear personal protective equipment. Fragments of workpieces or of a broken accessory may fly away and cause injury beyond the immediate area of operation
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 could give the operator an electric shock.
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 accessor
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.
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.
Regularly clean the power tool’s air vents. The motor’s fan will draw dust inside the housing and excessive accumulation of powdered metal may cause electrical hazards.
Do not operate the power tool near flammable materials. Sparks could ignite these materials.
Do not use accessories that require liquid coolants. Using water or other liquid coolants may result in electrocution or shock.

Kickback and Related Warnings 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 to 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 the direction of the wheel’s movement at the point of pinching. Abrasive wheels may also break under these conditions. Kickback is the result of power tool misuse and/or incorrect operating procedures or conditions and can be avoided by taking proper precautions as given below.

Maintain a firm grip on the power tool and position your body and arm to allow you to resist kickback forces. Always use an auxiliary handle, if provided, for maximum control over kickback or torque reaction during start-up. The operator can control torque reactions or kickback forces if proper precautions are taken.
Never place your hand near the rotating accessory. The accessory may kick back over your hand.
Do not position your body in the area where the power tool will move if kickback occurs. Kickback will propel the tool in a direction opposite to the wheel’s movement at the point of snagging
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.
Do not attach a saw chain woodcarving blade or toothed saw blade. Such blades create frequent kickbacks and loss of control.

Safety Warnings Specific for Grinding Operations:

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
The grinding surface of center-depressed wheels must be mounted below the plane of the guard lip. An improperly mounted wheel that projects through the plane of the guard lip cannot be adequately protected.
The guard must be securely attached to the power tool and positioned for maximum safety, so the least amount of wheel is exposed to the operator. The guard helps to protect the operator from broken wheel fragments, accidental contact with the wheel, and sparks that could ignite clothing.
Wheels must be used only for recommended applications.
Always use undamaged wheel flanges that are of the correct size and shape for your selected wheel. Proper wheel flanges support the wheel thus reducing the possibility of wheel breakage
Do not use worn-down wheels from larger power tools. The wheel intended for a larger power tool is not suitable for the higher speed of a smaller tool and may burst.

Safety Warnings Specific for Wire Brushing Operations:

Be aware that wire bristles are thrown by the brush even during ordinary operation. Do not overstress the wires by applying excessive load to the brush. The wire bristles can easily penetrate light clothing and/or skin.
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 workload and centrifugal forces.

Additional Safety Warnings:

When using depressed center grinding wheels, be sure to use only fiberglass-reinforced wheels.
NEVER USE Stone Cup-type wheels with this grinder. This grinder is not designed for these types of wheels and the use of such a product may result in serious personal injury.
Be careful not to damage the spindle, the flange (especially the installing surface), or the lock nut. Damage to these parts could result in wheel breakage.
Make sure the wheel is not contacting the workpiece before the switch is turned on.
Before using the tool on an actual workpiece, let it run for a while. Watch for vibration or wobbling that could indicate poor installation or a poorly balanced wheel.
Use the specified surface of the wheel to perform the grinding.
Do not leave the tool running. Operate the tool only when hand-held.
Do not touch the workpiece immediately after the operation; it may be extremely hot and could burn your skin.
Do not touch accessories immediately after the operation; it may be extremely hot and could burn your skin.
Observe the instructions of the manufacturer for the correct mounting and use of wheels. Handle and store wheels with care.
Do not use separate reducing bushings or adaptors to adapt large-hole abrasive wheels.
Use only the flanges specified for this tool.
For tools intended to be fitted with threaded hole wheels, ensure that the thread in the wheel is long enough to accept the spindle length
Check that the workpiece is properly supported.
Pay attention that the wheel continues to rotate after the tool is switched off.
If the working place is extremely hot and humid, or badly polluted by conductive dust, use a short-circuit breaker (30 mA) to assure operator safety.
Do not use the tool on any materials containing asbestos.
Do not use cloth work gloves during operation. Fibers from cloth gloves may enter the tool, which causes tool breakage.

SAVE THESE INSTRUCTIONS.
WARNING: DO NOT let comfort or familiarity with the product (gained from repeated use) replace strict adherence to safety rules for the subject product. MISUSE or failure to follow the safety rules stated in this instruction manual may cause serious personal injury.

FUNCTIONAL DESCRIPTION

CAUTION: Always be sure that the tool is switched off and unplugged before adjusting or checking the function on the tool.

Shaft lock
Press the shaft lock to prevent spindle rotation when installing or removing accessories.
► Fig.1: 1. Shaft lock
NOTICE: Never actuate the shaft lock when the spindle is moving. The tool may be damaged.
Switch action
CAUTION: Before plugging in the tool, always check to see that the switch trigger actuates properly and returns to the “OFF” position when released.
CAUTION: Do not pull the switch lever forc- ibly without pressing the lock-off button. The switch may break.
To prevent the switch lever from being accidentally pulled, a lock-off lever is provided. To start the tool, pull the lock-off lever toward the operator, and then pull the switch lever. release the switch lever to stop.
► Fig.2: 1. Lock-off lever 2. Switch lever
Unintentional restart proof
The tool does not start while pulling the switch lever even when the tool is plugged in. To start the tool, first, release the switch lever. Then pull the lock-off lever, and pull the switch lever.
NOTE: Wait more than one second before restarting the tool when unintentionally restarting proof functions.
Soft start feature
Soft start feature reduces starting of the reaction.

ASSEMBLY

CAUTION: Always be sure that the tool is switched off and unplugged before carrying out any work on the tool.

Installing side grip (handle)
CAUTION: Always be sure that the side grip is installed securely before operation.
Screw the side grip securely on the position of the tool as shown in the figure.
► Fig.3
Adjusting the angle of the wheel guard
WARNING: Make sure that the wheel guard is securely locked by the lock lever with one of the holes on the wheel guard.
The angle of the wheel guard can be adjusted.
While pushing the lock lever, rotate the wheel guard toward B, and then, change the angle of the wheel guard according to the work so that the operator can be protected. Align the lock lever with one of the holes in the wheel guard, and then release the lock lever to lock the wheel guard.
► Fig.4: 1. Wheel guard 2. Hole
Installing or removing the depressed center wheel or flap disc
Optional accessory
WARNING: When using a depressed center wheel or flap disc, the wheel guard must be fitted on the tool so that the closed side of the guard always points toward the operator.
CAUTION: Make sure that the mounting part of the inner flange fits into the inner diameter of the depressed center wheel/flap disc perfectly. Mounting the inner flange on the wrong side may result in a dangerous vibration.
Mount the inner flange onto the spindle.
Make sure to fit the dented part of the inner flange onto the straight part at the bottom of the spindle.
Fit the depressed center wheel/flap disc on the inner flange and screw the lock nut onto the spindle.
► Fig.5:

Lock nut
Depressed center wheel
Inner flange
Mounting part

To tighten the lock nut, press the shaft lock firmly so that the spindle cannot revolve, then use the lock nut wrench and securely tighten clockwise.
► Fig.6: 1. Lock nut wrench 2. Shaft lock To remove the wheel, follow the installation procedure in reverse.
Installing or removing flex wheel
Optional accessory
WARNING: Always use supplied guard when the flex wheel is on the tool. Wheel can shatter during use and the guard helps to reduce chances of personal injury.
► Fig.7:

Lock nut
Flex wheel
Back up pad
Inner flange
Follow instructions for the depressed center wheel but also use back up pad over the wheel. See the order of assembly on the accessories page in this manual.

OPERATION

WARNING: It should never be necessary to force the tool. The weight of the tool applies adequate pressure.
Forcing and excessive pressure could cause dangerous wheel breakage.
WARNING: ALWAYS replace the wheel if the tool is dropped while grinding.
WARNING: NEVER bang or hit the grinding disc or wheel onto work.
WARNING: Avoid bouncing and snagging the wheel, especially when working corners, sharp edges, etc. This can cause loss of control and kickback.
WARNING: NEVER use tools with wood cutting blades and other saw blades. Such blades when used on a grinder frequently kick and cause loss of control leading to personal injury.
WARNING: Continued use of a worn-out wheel may result in wheel explosion and serious personal injury.
CAUTION: Never switch on the tool when it is in contact with the workpiece, it may cause an injury to the operator.
CAUTION: Always wear safety goggles or a face shield during operation.
CAUTION: After the operation, always switch off the tool and wait until the wheel has come to a complete stop before putting the tool down.
CAUTION: ALWAYS hold the tool firmly with one hand on the housing and the other on the side grip (handle).
Operation with wheel/disc
► Fig.8
Turn the tool on and then apply the wheel or disc to the workpiece.
In general, keep the edge of the wheel or disc at an angle of about 15° to the workpiece surface.
During the break-in period with a new wheel, do not work the grinder in the forwarding direction or it may cut into the workpiece.
Once the edge of the wheel has been rounded off by use, the wheel may be worked in both forward and backward directions.
Operation with a wire wheel brush
Optional accessory
CAUTION: Check the operation of the wire wheel brush by the running tool with no load, insuring that no one is in front of or in line with the wire wheel brush.
CAUTION: Do not use a wire wheel brush that is damaged, or is out of balance. The use of a damaged wire wheel brush could increase the potential for injury from contact with broken wires.
CAUTION: ALWAYS use a guard with wire wheel brushes, assuring the diameter of the wheel fits inside the guard. The wheel can shatter during use and the guard helps to reduce chances of personal injury.
► Fig.9: 1. Wire wheel brush
Unplug the tool and place it upside down allowing easy access to the spindle.
Remove any accessories on the spindle. Thread wire wheel brushes onto the spindle and tighten with the wrenches.
NOTICE: Avoid applying too much pressure which causes overbending of wires when using a wire wheel brush. It may lead to premature breakage.
Lanyard (tether strap) connection
****Safety warnings specific for use at height
Read all safety warnings and instructions. Failure to follow the warnings and instructions may result in serious injury.

Always keep the tool tethered when working “at height”. Maximum lanyard length is 2 m. The maximum permissible fall height for the lanyard (tether strap) must not exceed 2 m.
Use only with lanyards appropriate for this tool type and rated for at least 4.0 kg.
Do not anchor the tool lanyard to anything on your body or on movable components. Anchor the tool lanyard to a rigid structure that can withstand the forces of a dropped tool.
Make sure the lanyard is properly secured at each end prior to use.
Inspect the tool and lanyard before each use for damage and proper function (including fabric and stitching). Do not use if damaged or not functioning properly. The tool must be repaired especially when a crack or a red line appears around the hole for the lanyard.
Do not wrap lanyards around or allow them to come in contact with sharp or rough edges.
Fasten the other end of the lanyard outside the working area so that a falling tool is held securely.
Attach the lanyard so that the tool will move away from the operator if it falls. Dropped tools will swing on the lanyard, which could cause injury or loss of balance.
Do not use near-moving parts or running machinery. Failure to do so may result in a crush or entanglement hazard.
Do not carry the tool by the attachment device or the lanyard.
Only transfer the tool between your hands while you are properly balanced.
Do not attach lanyards to the tool in a way that keeps guards, switches or lock-offs from operating properly.
Avoid getting tangled in the lanyard.
Keep the lanyard away from the cutting area of the tool.
Use a locking carabiner (multi-action and screw gate type). Do not use single-action spring clip carabiners.
In the event the tool is dropped, it must be tagged and removed from service, and should be inspected by a Makita Factory or Authorized Service Center.
Only attach the lanyard with a locking carabiner. Do not attach the lanyard by looping or knotting the lanyard. Do not use ropes or cords.
► Fig.10: 1. Hole for lanyard (tether strap)

MAINTENANCE

CAUTION: Always be sure that the tool is switched off and unplugged before attempting to perform inspection or maintenance.
NOTICE: Never use gasoline, benzine, thinner, alcohol, or the like. Discoloration, deformation or cracks may result.
To maintain product SAFETY and RELIABILITY, repairs, and any other maintenance or adjustment should be performed by Makita Authorized or Factory Service Centers, always using Makita replacement parts.
Air vent cleaning
The tool and its air vents have to be kept clean.
Regularly clean the tool’s air vents or whenever the vents start to become obstructed.
► Fig.11: 1. Exhaust vent 2. Inhalation vent

OPTIONAL ACCESSORIES

CAUTION: These accessories or attachments are recommended for use with your Makita tool specified in this manual. The use of any other accessories or attachments might present a risk of injury to persons. Only use accessory or attachment for its stated purpose. If you need any assistance with more details regarding these accessories, ask your local Makita Service Center.
► Fig.12

–| 100 mm (4″) model| 115 mm (4-1/2″) model| 125 mm (5″) model
---|---|---|---
1| Side grip
2| Inner flange| Inner flange / Super flange
3| Depressed center wheel / Flap disc
4| Lock nut
5| Back up pad
6| Flex wheel
7| Wire wheel brush
–| Lock nut wrench
–| Dust cover attachment

NOTE: Some items in the list may be included in the tool package as standard accessories. They may differ from country to country.

Makita Europe N.V. Jan-Baptist Vinkstraat 2, 3070 Kortenberg, Belgium
Makita Corporation 3-11-8, Sumiyoshi-cho, Anjo, Aichi 446-8502 Japan
www.makita.com