BOSCH GWS 12-125 S Professional Angle Grinder Instruction Manual

: May 15, 2024
: Bosch

Table of Contents

BOSCH GWS 12-125 S Professional Angle Grinder
Usage Instructions
Safety Instructions
Safety Warnings for Angle Grinder
Kickback and Related Warnings
Additional safety information
Product Features
Technical Data
Fitting
Operation
Maintenance and Service
Licenses
References
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BOSCH GWS 12-125 S Professional Angle Grinder

BOSCH-GWS-12-125-S-Professional-Angle-Grinder-PRODUCT-
IMAGE

Specifications:

Model: GWS 12-125 S
Manufacturer: Robert Bosch Power Tools GmbH
Power: 1200W
No-load Speed: 11000 min-1
Disc Diameter: 125mm
Spindle Thread: M14
Weight: 2.2kg (without additional handle), 2.0kg (with additional handle)
Protection Class: II

Product Description:
The Bosch GWS 12-125 S is a professional angle grinder designed for cutting, grinding, and sanding applications. It comes with various components including spindle lock button, on/off switch, speed selection dial, protective guard for cutting and grinding, dust extraction hood, flange with O-ring, different types of discs and attachments for various tasks.

Usage Instructions

Safety Instructions

Keep your work area clean and well-lit.
Use a residual current device if operating the tool in moist environments.
Only have the tool serviced by qualified personnel with genuine spare parts.

Special Safety Instructions for Grinding and Cutting:
Always unlock the power switch and place it in the off position when the power supply is interrupted to prevent accidental restarts.

Assembly:

Prior to any work on the tool, disconnect it from the power outlet.
Mount the necessary protective guard before operation.

FAQ:

Q: What should I do if the tool stops working?
A: If the tool malfunctions, stop using it immediately and have it inspected by authorized service personnel.
Q: Can I use accessories from other brands with this tool?
A: It is recommended to use Bosch-approved accessories to ensure compatibility and safety.

Safety Instructions

General Power Tool Safety Warnings
WARNING : Read all safety warnings and all in- structions. Failure to follow the warnings and instructions may result in electric shock, fire and/or serious injury.
Save all warnings and instructions for future reference.
The term “power tool” in the warnings refers to your mains-operated (corded) power tool or battery-operated (cord-less) power tool.

Work area safety

Keep work area clean and well lit. Cluttered or dark areas invite accidents.
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.
Keep children and bystanders away while operating a power tool. Distractions can cause you to lose control.

Electrical safety

Power tool plugs must match the outlet. Never modify the plug in any way. Do not use any adapter plugs with earthed (grounded) power tools. Unmodified plugs and matching outlets will reduce risk of electric shock.
Avoid body contact with earthed or grounded sur-faces, such as pipes, radiators, ranges and refrigerat- ors. There is an increased risk of electric shock if your body is earthed or grounded.
Do not expose power tools to rain or wet conditions. Water entering a power tool will increase the risk of elec-tric shock.
Do not abuse the cord. Never use the cord for carry-ing, 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.
When operating a power tool outdoors, use an exten-sion cord suitable for outdoor use. Use of a cord suit-able for outdoor use reduces the risk of electric shock..
If operating a power tool in a damp location is un-avoidable, use a residual current device (RCD) protec-ted supply. Use of an RCD reduces the risk of electric shock.

Personal safety

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 inatten-tion while operating power tools may result in serious per-sonal injury.
Use personal protective equipment. Always wear eye protection. Protective equipment such as dust mask, non-skid safety shoes, hard hat, or hearing protection used for appropriate conditions will reduce personal in-juries.
Prevent unintentional starting. Ensure the switch is in the off-position before connecting to power source and/or battery pack, picking up or carrying the tool. Carrying power tools with your finger on the switch or en-ergising power tools that have the switch on invites acci-dents.
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 in-jury.
Do not overreach. Keep proper footing and balance at all times. This enables better control of the power tool in unexpected situations.
Dress properly. Do not wear loose clothing or jew-ellery. Keep your hair, clothing and gloves away from moving parts. Loose clothes, jewellery or long hair can be caught in moving parts.
If devices are provided for the connection of dust ex-traction and collection facilities, ensure these are con-nected and properly used. Use of dust collection can re-duce dust-related hazards.

Power tool use and care

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 de-signed.
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.
Disconnect the plug from the power source and/or the battery pack from the power tool before making any adjustments, changing accessories, or storing power tools. Such preventive safety measures reduce the risk of starting the power tool accidentally.
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.
Maintain power tools. Check for misalignment or bind-ing 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.
Keep cutting tools sharp and clean. Properly main-tained cutting tools with sharp cutting edges are less likely to bind and are easier to control.
Use the power tool, accessories and tool bits etc. in accordance with these instructions, taking into ac-count the working conditions and the work to be per-formed. Use of the power tool for operations different from those intended could result in a hazardous situation.

Service

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.

Safety Warnings for Angle Grinder

Safety Warnings common for Grinding, Sanding, Wire Brushing or Abrasive Cutting Off operations

This power tool is intended to function as a grinder, sander, wire brush or cut-off tool. Read all safety warnings, instructions, illustrations and specifica-tions 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 are not recommended to be performed with this power tool. Operations for which the power tool was not designed may create a haz-ard and cause personal injury.
Do not use accessories which are not specifically de-signed 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 ac-cessory must be within the capacity rating of your power tool. Incorrectly sized accessories cannot be ad-equately guarded or controlled.
Threaded mounting of accessories must match the grinder spindle thread. For accessories mounted by flanges, the arbour hole of the accessory must fit the locating diameter of the flange. Accessories that do not match the mounting hardware of the power tool will run out of balance, vibrate excessively and may cause loss of control.
Do not use a damaged accessory. Before each use in-spect the accessory such as abrasive wheels for chips and cracks, backing pad for cracks, tear or excess wear, wire brush for loose or cracked wires. If power tool or accessory is dropped, inspect for damage or in-stall an undamaged accessory. After inspecting and installing an accessory, position yourself and bystand-ers 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 application, use face shield, safety goggles or safety glasses. As appropriate, wear dust mask, hearing pro-tectors, gloves and workshop apron capable of stop-ping small abrasive or workpiece fragments. The eye protection must be capable of stopping flying debris gen-erated by various operations . The dust mask or respir-ator 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 work area. Anyone entering the work area must wear personal protective equipment. Fragments of workpiece or of a broken accessory may fly away and cause injury beyond immediate area of operation.
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 ex-posed 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 accessory.
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 con-trol.
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 the dust inside the housing and excessive accumulation of powdered metal may cause electrical hazards.
Do not operate the power tool near flammable materi-als. Sparks could ignite these materials.
Do not use accessories that require liquid coolants. Using water or other liquid coolants may result in electro-cution or shock.

Kickback is a sudden reaction to a pinched or snagged rotat-ing wheel, backing pad, brush or any other accessory. Pinch-ing or snagging causes rapid stalling of the rotating access-ory which in turn causes the uncontrolled power tool to be forced in the direction opposite of the accessory’s rotation at the point of the binding. For example, if an abrasive wheel is snagged or pinched by the workpiece, the edge of the wheel that is entering into the pinch point can dig into the surface of the material causing the wheel to climb out or kick out. The wheel may either jump toward or away from the operator, depending on direc-tion of the wheel’s movement at the point of pinching. Abras-ive 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 auxiliary handle, if provided, for maximum control over kickback or torque reaction during start-up. The operator can control torque reac-tions or kickback forces, if proper precautions are taken.
Never place your hand near the rotating accessory. Accessory may kickback over your hand.
Do not position your body in the area where power tool will move if kickback occurs. Kickback will propel the tool in direction opposite to the wheel’s movement at the point of snagging.
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 kick-back and loss of control.

Safety Warnings specific for Grinding and Abrasive Cutting-Off operations

Use only wheel types that are recommended for your power tool and the specific guard designed for the se-lected wheel. Wheels for which the power tool was not designed cannot be adequately guarded and are unsafe.
The grinding surface of centre depressed wheels must be mounted below the plane of the guard lip. An im-properly 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 towards the operator. The guard helps to protect operator from broken wheel fragments, accidental contact with wheel and sparks that could ignite clothing.
Wheels must be used only for recommended applica-tions. For example: do not grind with the side of cut-off wheel. Abrasive cut-off wheels are intended for peri-pheral grinding, side forces applied to these wheels may cause them to shatter.
Always use undamaged wheel flanges that are of cor-rect size and shape for your selected wheel. Proper wheel flanges support the wheel thus reducing the pos-sibility of wheel breakage. Flanges for cut-off wheels may be different from grinding wheel flanges.
Do not use worn down wheels from larger power tools. Wheel intended for larger power tool is not suit-able for the higher speed of a smaller tool and may burst.

Additional Safety Warnings specific for Abrasive Cutting Off operations

Do not “jam” the cut-off wheel or apply excessive pressure. Do not attempt to make an excessive depth of cut. Overstressing the wheel increases the loading and susceptibility to twisting or binding of the wheel in the cut and the possibility of kickback or wheel breakage.
Do not position your body in line with and behind the rotating wheel. When the wheel, at the point of opera-tion, is moving away from your body, the possible kick-back may propel the spinning wheel and the power tool directly at you.
When wheel is binding or when interrupting a cut for any reason, switch off the power tool and hold the power tool motionless until the wheel comes to a com-plete stop. Never attempt to remove the cut-off wheel from the cut while the wheel is in motion otherwise kickback may occur. Investigate and take corrective ac-tion to eliminate the cause of wheel binding.
Do not restart the cutting operation in the workpiece. Let the wheel reach full speed and carefully re-enter the cut. The wheel may bind, walk up or kickback if the power tool is restarted in the workpiece.
Support panels or any oversized workpiece to minim- ize the risk of wheel pinching and kickback. Large workpieces tend to sag under their own weight. Supports must be placed under the workpiece near the line of cut and near the edge of the workpiece on both sides of the wheel.
Use extra caution when making a “pocket cut” into ex-isting walls or other blind areas. The protruding wheel may cut gas or water pipes, electrical wiring or objects that can cause kickback.

Safety Warnings specific for Sanding operations
Do not use excessively oversized sanding disc paper. Follow manufacturers recommendations, when select-ing sanding paper. Larger sanding paper extending bey-ond the sanding pad presents a laceration hazard and may cause snagging, tearing of the disc, or kickback.

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 brush-ing, do not allow any interference of the wire wheel or brush with the guard. Wire wheel or brush may expand in diameter due to work load and centrifugal forces.

Additional safety information

$BOSCH-GWS-12-125-S-Professional-Angle-Grinder-$5$$ Wear safety goggles.

Use suitable detectors to determine if utility lines are hidden in the work area or call the local utility com-pany for assistance. Contact with electric lines can lead to fire and electric shock. Damaging a gas line can lead to explosion. Penetrating a water line causes property dam-age or may cause an electric shock.
Do not touch grinding and cutting discs until they have cooled down. The discs can become very hot while work-ing.
Release the On/Off switch and set it to the off position when the power supply is interrupted, e. g., in case of a power failure or when the mains plug is pulled. This prevents uncontrolled restarting.
Secure the workpiece. A workpiece clamped with clamping devices or in a vice is held more secure than by hand.

Products sold in GB only:
Your product is fitted with an BS 1363/A approved electric plug with internal fuse (ASTA approved to BS 1362).
If the plug is not suitable for your socket outlets, it should be cut off and an appropriate plug fitted in its place by an au-thorised customer service agent. The replacement plug should have the same fuse rating as the original plug. The severed plug must be disposed of to avoid a possible shock hazard and should never be inserted into a mains socket elsewhere.

Product Description and Specifications
$BOSCH-GWS-12-125-S-Professional-Angle-Grinder-$6$$ Read all the safety and general instructions. Failure to observe the safety and general in-structions may result in electric shock, fire and/or serious injury.
Please observe the illustrations at the beginning of this oper-ating manual.

Intended use
The power tool is intended for cutting, roughing and brush-ing metal and stone materials, as well as making holes in stone materials using diamond core cutters, without the use of water.
A separate protective guard for cutting must be used when cutting with bonded abrasives. Sufficient dust extraction must be provided when cutting stone. With approved abrasive tools, the power tool can be used for sanding with sanding discs. The power tool must not be used to grind concrete.

Product Features

The numbering of the product features refers to the diagram of the power tool on the graphics page.

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Unlocking lever for protective guard
Spindle lock button
On/off switch
Speed preselection thumbwheel
Auxiliary handle (insulated gripping surface)
Protective guard for cuttinga)
Protective guard for grinding
Extraction guard for grindinga)
Mounting flange with O‑ring
Carbide grinding heada)
Grinding disca)
Cutting disca)
Quick-clamping nut a)
Clamping nut
Quick-clamping nut with bara)
Two-pin spanner for clamping nut
Grinding spindle
Handle (insulated gripping surface)
Extraction guard for cutting with cutting guidesa)
Diamond cutting disca)
Hand guarda)
Cup brusha)
Rubber sanding pada)
Abrasive disca)
Round nuta)
Diamond annular cuttera)
Open-ended spannera)

a) Accessories shown or described are not included with the product as standard. You can find the complete selection of accessories in our accessories range.

Technical Data

The specifications apply to a rated voltage [U] of 230 V. These spe- cifications may vary at different voltages and in country-specific mod-els.

Noise/Vibration Information
Noise emission values determined according to EN 60745-2-3.
Typically the A-weighted noise level of the power tool are: 93 dB(A); sound power level 104 dB(A). Uncertainty K = 3 dB.

Wear hearing protection!
Vibration total values ah (triax vector sum) and uncertainty K determined according to EN 60745-2-3:
Surface grinding (roughing): ah = 5.9 m/s2, K = 1.5 m/s2,
Disc sanding: ah < 2.5 m/s2, K = 1.5 m/s2.
The vibration level given in these instructions has been measured in accordance with a standardised measuring procedure and may be used to compare power tools. It can also be used for a preliminary estimation of exposure to vibration. The stated vibration level applies to the main applications of the power tool. However, if the power tool is used for different applications, with different application tools or poorly maintained, the vibration level may differ. This can significantly increase the exposure to vibration over the total working period.
To estimate the exposure to vibration accurately, the times when the tool is switched off or when it is running but not actually being used should also be taken into account. This can significantly reduce the exposure to vibration over the total working period. Implement additional safety measures to protect the operator from the effects of vibration, such as servicing the power tool and application tools, keeping the hands warm, and organising workflows correctly.

Fitting

Fitting Protective Equipment

Pull the plug out of the socket before carrying out any work on the power tool.

Note: If the grinding disc breaks during operation or the holding fixtures on the protective guard/power tool become damaged, the power tool must be sent to the after-sales service immediately; see the “After-Sales Service and Application Service” section for addresses.

Protective guard for grinding

Place the protective guard (7) onto the holder on the power tool until the coding cams of the protective guard are aligned with the holder. When doing so, press and hold the unlocking lever (1). Press the protective guard (7) onto the spindle collar un-til the shoulder of the pro-tective guard is sitting on the flange of the power tool and rotate the protective guard until it audibly clicks into place. Adjust the position of the protective guard (7) to meet the requirements of the operation. To do this, push the unlock-ing lever (1) upward and rotate the protective guard (7) into the required position.

Always position the protective guard (7) such that the two cams on the unlocking lever (1) engage in the corresponding openings on the protective guard (7).
Adjust the protective guard (7) such that sparking in the direction of the operator is prevented.
The protective guard (7) must only be adjustable while the unlocking lever (1) is actuated. Otherwise, the power tool must not be used any more under any circumstances and must be sent to the after-sales service.

Note: The coding cams on the protective guard (7) ensure that only a protective guard that is suitable for the power tool can be fitted.

Extraction guard for cutting with a guide block
The extraction guard for cutting with a cutting guide (19) is fitted in the same way as the protective guard for grinding. By securing the auxiliary handle (5) with the clip through the extraction guard on the gearbox housing, the power tool is firmly attached to the extraction guard. A suitable Bosch dust extractor can be connected to the extraction guard with a cutting guide (19). To do so, insert the vacuum hose with dust extraction adapter into the provided receiving connec-tion of the extraction guard.
Note: The friction generated by the dust in the vacuum hose and accessory during extraction causes an electrostatic charge that the user may experience as static discharge (de-pending on environmental factors and their physiological state). Bosch generally recommends using an anti-static va-cuum hose (accessory) to vacuum up fine dust and dry ma-terials.

Protective guard for cutting

Always use the protective guard for cutting (6) when cutting with bonded abrasives.
Provide sufficient dust extraction when cutting stone.

The protective guard for cutting (6) is fitted in the same way as the protective guard for grinding (7).

Extraction guard for cutting with a guide block
The extraction guard for cutting with a guide block (19) is fit-ted in the same way as the protective guard for grinding.

Hand guard

Always fit the hand guard (21) when working with the rubber sanding pad (23) or with the cup brush/flap disc/diamond annular cutter.
Attach the hand guard (21) to the side handle (5).

Side handle

Do not operate your power tool without the side handle (5).
Do not continue to use the power tool if the auxiliary handle is damaged. Do not make any alterations to the auxiliary handle.
Screw the side handle (5) on the left or right of the machine head depending on how your are working.

Low-vibration auxiliary handle
Screw the auxiliary handle (5) on the right or left of the machine head depending on the working method. The low-vibration auxiliary handle reduces vibration, en-abling the tool to be used safely and more comfortably.

Do not operate your power tool without the side handle (5).
Do not make any alterations of any kind to the auxili-ary handle.
Do not continue to use a damaged auxiliary handle.

Fitting the Abrasive Tools

Pull the plug out of the socket before carrying out any work on the power tool.
Do not touch grinding and cutting discs until they have cooled down. The discs can become very hot while working.
Clean the grinding spindle (17) and all the parts to be fitted.
Lock the grinding spindle with the spindle lock button (2) before clamping and releasing the abrasive tools.
Do not press the spindle lock button while the grinding spindle is moving. The power tool may become dam-aged if you do this.

Grinding/cutting disc
Assembly with Clamping Nut (14) and Quick-Clamping Nut (13) Pay attention to the dimensions of the abrasive tools. The diameter of the hole must match that of the mounting flange. Do not use an adapter or reducer. When using diamond cutting discs, ensure that the arrow indicating the direction of rotation on the diamond cutting disc matches the direction of rotation of the power tool (see the direction of rotation arrow on the machine head). See the graphics page for assembly instructions. To fasten the grinding/cutting disc, screw on the clamping nut (14) and tighten with the two-hole spanner. (see ” Quick- clamping nut “, page 23). A plastic part (O-ring) is fitted around the cent- ring collar in the mounting flange (9). If the O-ring is missing or damaged, the mounting flange (9) must be replaced before operation can resume.

After fitting the abrasive tool, check that the abrasive tool is fitted correctly and can turn freely before switching on the power tool. Make sure that the abras-ive tool does not brush against the protective guard or other parts.

Assembly with Quick-clamping Nut (15)
Pay attention to the dimensions of the abrasive tools. The diameter of the hole must match that of the mounting flange. Do not use an adapter or reducer. When using diamond cutting discs, make sure that the direction of rotation arrow on the diamond cutting disc corresponds to the direction of rotation of the machine (see direction of rotation arrow on the housing). See the graphics page for fitting instructions. Use the quick-clamping nut (15) to secure the grinding/cut-ting disc without the need for additional tools. The quick- clamping nut (15) may be used only for grinding or cutting discs. Only use quick-clamping nuts (15) that are in good working order and not damaged. When screwing on, make sure that the printed side of the quick-clamping nut (15) is not facing the grinding disc.

Press the spindle lock but-ton (2) to lock the grinding spindle. To tighten the quick-clamping nut (15), fold up the bar and turn the quick-clamping nut firmly clockwise. Then fold down the bar to secure the quick-clamping nut. It is not suf-ficient to tighten the disc along the edge.

Quick-clamping nuts (15) that are properly secured and not damaged can be re- moved by hand. To do this, fold up the bar and turn the quick-clamping nut firmly anticlockwise. If the quick-clamping nut is stuck, do not attempt to loosen it with a tool – always use a two-pin spanner. After fitting the hub flange and the grinding/cutting disc, the free thread length of the grinding spindle must be at least 4 mm. Ensure that the abrasive tool is firmly seated, so that it does not twist away from the spindle in the runout of the power tool.

A plastic part (O-ring) is fitted around the cent-ring collar in the hub flange (9). If the O-ring is missing or damaged, the hub flange (9) must be replaced before operation can re-sume.

After fitting the abrasive tool, check that the abrasive tool is fitted correctly and can turn freely before switching on the power tool. Make sure that the abras-ive tool does not brush against the protective guard or other parts.

Flap disc

Always fit the hand guard (21) when working with the flap disc.

Rubber sanding pad

Always fit the hand guard (21) when working with the rubber sanding pad (23).

See the graphics page for fitting instructions. Screw on the round nut (25) and tighten with the two-pin spanner.

Cup brush
Always fit the hand guard (21) when working with the cup brush. See the graphics page for fitting instructions. The cup brush must be screwed onto the grinding spindle until it rests firmly against the grinding spindle flange at the end of the grinding spindle thread. Tighten the cup brush with an open- ended spanner.

Quick-clamping nut
To change the abrasive tool easily without having to use any additional tools, you can use the quick-clamping nut (13) in-stead of the clamping nut (14).

The quick-clamping nut (13) may be used only for grinding or cutting discs.

Only use quick-clamping nuts (13) that are in good working order and not damaged. When screwing on, make sure that the printed side of the quick- clamping nut (13) is not facing the grinding disc; the arrow must be pointing towards the index mark (28).

Press the spindle lock button (2) to lock the grinding spindle. To tighten the quick-clamping nut, turn the grinding disc firmly clockwise
If the quick-clamping nut has been attached correctly and is not damaged, you can loosen it by hand by turning the knurled ring anticlockwise. If the quick clamping nut is stuck, do not attempt to loosen it with pliers – always use the two-pin spanner. Position the two‑pin spanner as shown in the figure.

Approved abrasive tools
You can use all the abrasive tools mentioned in these operating instructions. The permissible speed [min-1] or the circumferential speed [m/s] of the abrasive tools used must at least match the values given in the table. It is therefore important to observe the permissible rotational/circumferential speed on the label of the abrasive tool.

Rotating the Machine Head

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Pull the plug out of the socket before carrying out any work on the power tool.

The machine head can be rotated in 90° increments. In this way, the on/off switch can be brought into a more favourable handling position for particular applications, e.g. for left-handed tool users.
Completely unscrew the four screws. Rotate the machine head carefully, without removing it from the housing, into the new position. Screw in and retighten the four screws.

Dust/Chip Extraction
The dust from materials such as lead paint, some types of wood, minerals and metal can be harmful to human health. Touching or breathing in this dust can trigger allergic reactions and/or cause respiratory illnesses in the user or in people in the near vicinity. Certain dusts, such as oak or beech dust, are classified as carcinogenic, especially in conjunction with wood treatment additives (chromate, wood preservative). Materials containing asbestos may only be machined by specialists.

Use a dust extraction system that is suitable for the material wherever possible.
Provide good ventilation at the workplace.
It is advisable to wear a P2 filter class breathing mask. The regulations on the material being machined that apply in the country of use must be observed.
Avoid dust accumulation at the workplace. Dust can easily ignite.

Operation

Start-Up

Pay attention to the mains voltage. The voltage of the power source must match the voltage specified on the rating plate of the power tool. Power tools marked with 230 V can also be operated with 220 V.
Products that are only sold in AUS and NZ: Use a resid-ual current device (RCD) with a nominal residual current of 30 mA or less.
When operating the power tool using a mobile generator that does not have sufficient reserve capacity or an adequate voltage control system with inrush current boost converter, loss of performance or atypical behaviour may occur upon switch-on.
Please check the suitability of the power generator you are using, particularly with regard to the mains voltage and frequency.

Switching on/off

To start the power tool, push the on/off switch (3) forward. To lock the on/off switch (3) in position, push the on/off switch (3) forward and down until it clicks into place.
To switch off the power tool, release the on/off switch (3); or, if the switch is locked, briefly push the on/off switch (3) backward and down and then release it.
Always check abrasive tools before using them. The abrasive tool must be fitted properly and be able to move freely. Carry out a test run for at least one minute with no load. Do not use abrasive tools that are damaged, run untrue or vibrate during use. Damaged abrasive tools can burst apart and cause injuries.

Restart protection
The restart protection feature prevents the power tool from uncontrolled starting after the power supply to it has been interrupted. To restart the tool, set the on/off switch (3) to the off posi-tion and then switch the power tool on again.

Soft start
The electronic soft start limits the torque when the power tool is switched on and enables a smooth start-up.
Note: If the power tool runs at full speed immediately after being switched on, this means that the soft start and restart protection mechanisms have failed. The power tool must be sent to the after-sales service immediately; see the “After-Sales Service and Application Service” section for ad-dresses.

Kickback control
If there is a sudden kickback in the power tool, e.g. jamming in a separating cut, the power supply to the motor will be interrupted electronically.
To restart the tool, set the On/Off switch (3) to the “off” po-sition and then switch the power tool on again.

Constant Electronic control
The Constant Electronic keeps the speed at no load and un-der load virtually consistent, guaranteeing uniform performance.

Speed preselection
You can select the required speed using the speed preselection thumbwheel (4), even during operation. The information in the table below describes the recommended values.

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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.

Level Speed preselection| GWS 12-125 S [min – 1 ]
---|---
1| 2800
2| 3900
3| 5200
4| 6500
5| 8100
6| 11,000

The values specified for speed levels are guide values.

Working Advice

Pull the plug out of the socket before carrying out any work on the power tool.
Exercise caution when cutting slots in structural walls; see the “Information on structural design” section.
Clamp the workpiece if it is not secure under its own weight.
Do not load the power tool so heavily that it comes to a stop.
If the power tool has been subjected to a heavy load, continue to run it at no-load for several minutes to cool down the accessory.
Do not use the power tool with a cut-off stand.
Do not touch grinding and cutting discs until they have cooled down. The discs can become very hot while work-ing.

Flap Disc
With the flap disc (accessory), curved surfaces and profiles can be worked. Flap discs have a considerably higher service life, lower noise levels and lower sanding temperatures than conventional sanding sheets.

Rough grinding

Never use cutting discs for rough grinding.

The best rough grinding results are achieved with a set angle of 30° to 40°. Move the power tool back and forth with mod-erate pressure. This will ensure that the workpiece does not become too hot or discolour and that grooves are not formed.

Cutting Metal

Always use the protective guard for cutting (6) when cutting with bonded abrasives.

When carrying out abrasive cutting, use a moderate feed that is suited to the material being machined. Do not exert pressure on the cutting disc and do not tilt or swing the power tool.
Do not attempt to reduce the speed of a cutting disc coming to a stop by applying pressure from the side.

The power tool must always work in an up-grinding mo-tion. Otherwise, there is a risk that it will be pushed uncontrolled out of the cut. For best results when cut-ting profiles and rectangular tubing, start at the smallest cross section.

Cutting stone

Provide sufficient dust extraction when cutting stone.
Wear a dust mask.
The power tool may be used only for dry cutting/grind-ing.

For best results when cutting stone, use a diamond cutting disc. When using the extraction guard for cutting with a guide block (19), the vacuum cleaner must be approved for
vacuuming stone dust. Suitable vacuum cleaners are available from Bosch.

Switch on the power tool and position it with the front part of the guide block on the workpiece. Move the power tool with a moderate feed motion that is suited to the material being
machined. When cutting especially hard materials such as concrete with a high pebble content, the diamond cutting disc can overheat and become damaged as a result. This is clearly indicated by circular sparking, rotating with the dia- mond cutting disc. If this happens, stop cutting and allow the diamond cutting disc to cool down by running the power tool for a short time at maximum speed with no load. Working noticeably slower and with circular sparking indic-ate that the diamond cutting disc that has become dull. You can resharpen the disc by briefly cutting into abrasive material (e.g. lime-sand brick).

Cutting hard materials
Wear a suitable dust mask, e.g. P2 Standard. The power tool may be used only for dry cutting/grind-ing. For cutting especially hard material, e.g., concrete with high pebble content, the diamond cutting disc can overheat and become damaged as a result. This is clearly indicated by cir-cular sparking, rotating with the diamond cutting disc. In this case, interrupt the cutting process and allow the dia-mond cutting disc to cool by running the power tool for a short time at maximum speed with no load. Noticeably decreasing work progress and circular sparking are indications of a diamond cutting disc that has become dull. Briefly cutting into abrasive material (e.g. lime-sand brick) can resharpen the disc again.

Working with Diamond Annular Cutters
Only use dry diamond annular cutters. Always fit the hand guard (21) when working with dia-mond annular cutters. Do not place the diamond annular cutter parallel to the work-piece. Plunge it into the workpiece at an angle and in a circu-lar motion. This will allow you to achieve optimal cooling and ensure a longer tool life for the diamond annular cutter.

Information on structural design
Slots in load-bearing walls are subject to DIN 1053 part 1 or country-specific regulations. These regulations must be ob-served under all circumstances. Seek advice from the responsible structural engineer, architect or construction supervisor before starting work.

Maintenance and Service

Maintenance and Cleaning

Pull the plug out of the socket before carrying out any work on the power tool.
To ensure safe and efficient operation, always keep the power tool and the ventilation slots clean.
In extreme conditions, always use a dust extractor if possible. Blow out ventilation slots frequently and install a residual current device (RCD) upstream. When machining metals, conductive dust can settle inside the power tool, which can affect its protective insulation. Store and handle the accessories carefully.
In order to avoid safety hazards, if the power supply cord needs to be replaced, this must be done by Bosch or by an after-sales service centre that is authorised to repair Bosch power tools.

Clean the air vents on your power tool regularly. The motor’s fan will draw the dust inside the housing and excessive accumulation of powdered metal may cause electrical hazards.

After-Sales Service and Application Service
Our after-sales service responds to your questions concerning maintenance and repair of your product as well as spare parts. You can find explosion drawings and information on spare parts at: www.bosch-pt.com
The Bosch product use advice team will be happy to help you with any questions about our products and their accessories. In all correspondence and spare parts orders, please always include the 10‑digit article number given on the nameplate of the product.
Great Britain
Robert Bosch Ltd. (B.S.C.)
P.O. Box 98
Broadwater Park
North Orbital Road
Denham Uxbridge
UB 9 5HJ
At www.bosch-pt.co.uk you can order spare parts or arrange the collection of a product in need of servicing or repair. Tel. Service: (0344) 7360109
E-Mail: boschservicecentre@bosch.com
You can find further service addresses at: www.bosch- pt.com/serviceaddresses

Disposal
The power tool, accessories and packaging should be re-cycled in an environmentally friendly manner.
Do not dispose of power tools along with household waste.

Only for EU countries:
According to the European Directive 2012/19/EU on Waste Electrical and Electronic Equipment and its implementation into national law, power tools that are no longer usable must be collected separately and disposed of in an environment-ally friendly manner. If disposed incorrectly, waste electrical and electronic equipment may have harmful effects on the environment and human health, due to the potential presence of hazardous substances.

Only for United Kingdom:
According to The Waste Electrical and Electronic Equipment Regulations 2013 (SI 2013/3113) (as amended), products that are no longer usable must be collected separately and disposed of in an environmentally friendly manner.

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Licenses

Copyright © 2020, Microchip Technology Inc. and its subsidiaries (“Microchip”)
All rights reserved.
This software is developed by Microchip Technology Inc. and its subsidiaries (“Microchip”).
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following con-ditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Microchip’s name may not be used to endorse or promote products derived from this software without specific prior writ-ten permission.

THIS SOFTWARE IS PROVIDED BY MICROCHIP “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MICROCHIP BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTI-AL DAMAGES (INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DA-TA OR PROFITS; OR BUSINESS INTERRUPTION) HOWSOEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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