BOSCH GAC 250 Professional Concrete Block Saw Instruction Manual

: June 12, 2024
: Bosch

BOSCH GAC 250 Professional Concrete Block Saw

BOSCH GAC 250 Professional Concrete Block Saw product

Product Information

The GAC 250 Professional is a Porenbeton-Schneider manufactured by Robert Bosch Power Tools GmbH. It has a Sachnummer of 3 601 BB60.. and a nominal power input of 1200W. The chain speed is 12m/s, and it has a chain pitch of 1.3mm. The toolless chain tensioning system (SDS) makes it easy to adjust the chain tension as required.
It has a front brake, an emergency brake, and a stopper for safety.
The tool has a weight of 4.7kg and is classified under protection class II.

Product Usage Instructions

Before using the GAC 250 Professional, read the user manual carefully and ensure that you follow all safety instructions. Here are some basic usage instructions:

Always wear personal protective equipment such as safety gloves, non-slip shoes, and a dust mask while operating the tool.
Avoid using the tool in wet or damp conditions. If necessary, use a residual current device to reduce the risk of electric shock.
Do not use the tool in the rain.
Keep bystanders away from your work area.
Use only original replacement parts to repair your power tool and have it serviced by qualified personnel to ensure its safety.
Do not allow dust to accumulate in your work area.
To turn on the tool, press the On/Off switch located at position (2) on the tool diagram.
To adjust the chain tension, use the toolless chain tensioning system (SDS) located at position (3) on the tool diagram.

Safety Notes

General Power Tool Safety Warnings

WARNING Read all safety warnings, instruc-tions, illustrations and specifications provided with this power tool. Failure to follow all in- structions 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 (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 a 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 and clothing 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.
Do not let familiarity gained from frequent use of tools allow you to become complacent and ignore tool safety principles. A careless action can cause severe in-jury within a fraction of a second.

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 re-move the battery pack, if detachable, from the power tool before making any adjustments, changing ac-cessories, 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 and accessories. Check for mis-alignment or binding of moving parts, breakage of parts and any other condition that may affect the power tool’s operation. If damaged, have the power tool repaired before use. Many accidents are caused by poorly maintained power tools.
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.
Keep handles and grasping surfaces dry, clean and free from oil and grease. Slippery handles and grasping surfaces do not allow for safe handling and control of the tool in unexpected situations.

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.

Special Safety Instructions for AAC Block Cutter

Keep all parts of the body away from the saw chain when the saw is running. Before starting up the saw, ensure that the saw chain is not touching anything. When working with a power tool, a moment of inattention could lead to clothing or parts of the body being caught by the saw chain.
Always hold the power tool with your right hand on the rear grip and your left hand on the front grip. Hold-ing the power tool with the reversed hand configuration increases the risk of injuries and must not be used.
Only hold the power tool by the insulated gripping sur-faces because the saw chain may come into contact with hidden electrical cables or its own power cable. If the saw chain comes into contact with a live wire, this may make metal parts of the tool live as well, posing a risk of electric shock.
Wear protective eyewear and a dust mask. Additional protective equipment for ears, head, hands, legs and feet is recommended. Appropriate protective clothing reduces the risk of injury from flying chip material and anything accidentally coming into contact with the saw chain.
Do not work with the power tool on a ladder, from a roof or on an unstable support. Operating a power tool in this way may lead to serious injuries.
Always ensure that you have a secure footing and only use the power tool if you are standing on solid, secure and level ground. Slippery or unstable surfaces can cause you to lose your balance or lose control over the power tool.
With the power tool switched off, carry it by the front grip with the saw chain facing forwards. Always put on the protective cover when transporting or storing the power tool. Handling the power tool carefully reduces the likelihood of the running saw chain accidentally com-ing into contact with an object.
Follow the instructions for the chain tension and for changing the saw blade body and the chain. A chain that is not tensioned correctly may break or may increase the risk of kickback.
Only saw autoclaved aerated concrete. The power tool must not be used for work that it is not intended for. Example: Do not use the power tool to saw metal, plastic, masonry, soil, ice or wood. Using the power tool for work that is not intended for may lead to dangerous situations.
If you are removing accumulated material, storing the power tool or performing maintenance, follow all of the instructions. Ensure that the on/off switch is switched off and the mains plug is not plugged in. Un-intentionally activating the power tool when removing ac-cumulated material or during maintenance may lead to serious injuries.

Causes of kickbacks and prevention:

Kickbacks may occur if the tip of the guide rail comes into contact with an object.
If an object comes into contact with the tip of the guide rail, it may cause the power tool to react unexpectedly in a backwards direction, during which the guide rail is knocked upwards and in the direction of the operator.
If the saw chain jams on the top edge of the guide rail, the rail may quickly kick back in the direction of the oper-ator.
Any of these reactions may lead to you losing control of the power tool or seriously injuring yourself. Do not solely rely on the safety devices built into the power tool. As the user of a power tool, you should take a number of meas-ures so that you can work without accidents or injuries. Kickback is the result of misuse or incorrect use of the power tool. It can be avoided by taking proper precau-tions as given below.
Hold the power tool firmly with both hands, with the handles of the power tool grasped with your thumb and finger. Move your body and arms into a position from which you can withstand the kickback forces. If suitable measures are taken, the operator can control the kickback forces. Never let go of the power tool.
Avoid adopting an abnormal posture and do not saw above shoulder height. This prevents the tip of the guide rail accidentally coming into contact with an object and gives you better control of the power tool if unexpected situations occur.
Always use replacement rails, saw chains and sprocket wheels specified by the manufacturer. Using incorrect replacement rails, saw chains and sprocket wheels may cause the chain to break or lead to kickbacks.
Always follow the manufacturer’s instructions for maintaining the saw chain. Setting depth gauges too low increases the likelihood of kickbacks.

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.

Explanation of symbols

BOSCH GAC 250 Professional Concrete Block Saw 11

Product Description and Specifications

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 exclusively intended for sawing autoclaved aerated concrete.
Product Features
The numbering of the product features refers to the diagram of the power tool on the graphics page.

Rear handle
On/off switch
Front handle
Handguard/lever for activating the front brake
Serial number
Nose sprocket
Chain guard
TCT saw chain
Chain bar
Stop
Lock-on button
Cover
Tension wheel
Lock-off function for on/off switch
Extraction outlet
Running direction and cutting direction symbol
Sprocket wheel
Fastening bolt
Guide bar for chain bar
Extraction hose
Bolt

Technical Data

BOSCH GAC 250 Professional Concrete Block Saw 13

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.
Starting cycles generate brief voltage drops. Interference with other equipment/machines may occur in case of unfavourable mains sys-tem conditions. Malfunctions are not to be expected for system im-pedances below 0.25 ohm.
Noise/Vibration Information
Noise emission values determined according to EN 62841-1.
Typically, the A-weighted noise level of the power tool is: Sound pressure level 95 dB(A); sound power level 103 dB(A). Uncertainty K = 3 dB.
Wear hearing protection!
Vibration total values ah (triax vector sum) and uncertainty K determined according to EN 62841-1:
ah = 3.9 m/s2, K = 1.5 m/s2.
The vibration level and noise emission value given in these instructions have been measured in accordance with a standardised measuring procedure and may be used to com-pare power tools. They may also be used for a preliminary estimation of vibration and noise emissions.
The stated vibration level and noise emission value repres-ent the main applications of the power tool. However, if the power tool is used for other applications, with different ap-plication tools or is poorly maintained, the vibration level and noise emission value may differ. This may significantly increase the vibration and noise emissions over the total working period.
To estimate vibration and noise emissions 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 may significantly reduce vibration and noise emissions over the total working period.
Implement additional safety measures to protect the oper-ator from the effects of vibration, such as servicing the power tool and application tools, keeping their hands warm, and organising workflows correctly.

Assembly

For Your Safety

Warning! Switch off, remove plug from mains before adjusting or cleaning. The same applies when the mains cable is damaged, cut or entangled.
Caution! Do not touch the rotating chain.
Never operate the power tool in the vicinity of per-sons, children or animals or after consuming alcohol, drugs or taking numbing medication.

Mounting and Tensioning the Chain Saw

Only connect the power tool to the mains supply once it has been fully assembled.
Always wear protective gloves when handling the chain.

Assembling the Chain Bar and Saw Chain

Carefully unpack all of the parts.
Set down the power tool on a level surface.
Insert the saw chain (8) into the circumferential groove of the chain bar (9). Ensure that the running direction is cor-rect. To do this, compare the saw chain against the run-ning direction symbol (16).
Make sure that the tension wheel (13) is in the – position.
Put the chain links around the sprocket wheel (17) and position the chain bar (9) on the fastening bolt (18). Note: During initial assembly, the bolt (21) must engage in the mounting hole on the chain bar (9) that is furthest away from the sprocket wheel (17) (see figure A).
Check whether all of the parts are positioned correctly and hold the chain bar with the saw chain in this position. Then turn the tension wheel (13) in the + direction until the saw chain is partially tensioned and remains mounted on the chain bar.
Replace the cover (12).
Tighten the cover (12) slightly with the lock-on button (11).
The saw chain is not yet fully tensioned. The saw chain is tensioned as described in the “Tensioning the Saw Chain” section.

Tensioning the Saw Chain
Check the chain tension regularly every ten minutes, includ-ing before starting work, after the initial steps and during sawing. Particularly when using new saw chains, increased extension should be expected initially.
The service life of the saw chain relies heavily on it being ten-sioned correctly.
Do not tension the saw chain if it is strongly heated because it will tighten once it has cooled down and it will fit too tightly on the chain bar.

Set down the power tool on a level surface.
Turn the lock-on button (11) in the direction in order to release the fixed chain bar.
Check whether the chain links are correctly positioned in the guide slot of the chain bar (9) and on the sprocket wheel (17).
Turn the tension wheel (13) in the + direction until the correct chain tension has been reached. The latching mechanism stops the chain tension from being released. If the tension wheel (13) is hard to turn, you must con-tinue to loosen the lock-on button (11) in the direc-tion. The lock-on button (11) can also rotate if the tension wheel (13) is set. Two hands may be required to hold the lock-on button (11) in position while setting the tension wheel (13).
The saw chain (8) is tensioned correctly if it can be lifted in the middle by approx. 3–4 mm. This should be done with one hand by pulling up the saw chain against the power tool’s own weight.
If the saw chain (8) is tensioned excessively, turn the ten-sion wheel (13) in the – direction.
When the saw chain (8) is tensioned, secure the chain bar (9) by turning the lock-on button (11) in the direc-tion. Do not use a tool to do this.

Dust/chip extraction

Dust from materials can be harmful to 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 are classified as carcinogenic.

Use a dust extraction system that is suitable for the ma-terial wherever possible.
Provide good ventilation at the workplace.
It is advisable to wear a P2 filter class breathing mask.

Avoid dust accumulation at the workplace. Dust can easily ignite.
External Dust Extraction
Insert the extraction hose (20) with adapter into the extrac-tion outlet (15). Connect the dust extraction hose to a dust extractor (accessory). You will find an overview of how to connect to various dust extractors at the end of these oper-ating instructions.
The power tool can be directly connected to the socket of a Bosch all-purpose dust extractor with remote starter. This dust extractor is started up automatically when the power tool is switched on.
The dust extractor must be suitable for the material being worked. BOSCH GAC
250 Professional Concrete Block Saw 10 When extracting dry dust or dust that is especially detri-mental to health or carcinogenic, use a special dust extractor.

Operation

Starting Operation

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.

Switching On and Off
Pull the hand guard/lever for activating the front brake (4) from position to position in the direction of the front handle (3) (see figure E). If you have not op-erated the hand guard/lever for activating the front brake (4), the front brake has not been deactivated be-fore use and the power tool will not start up.
Remove the chain guard (7).
Hold the power tool as described in the “Working with the Power Tool” section.
To start the power tool, first press the lock-off button (14), then press and hold the on/off switch (2).
If the power tool is running, you can release the lock-off func-tion.
To switch off the power tool, release the on/off switch (2). Note: For safety reasons, the on/off switch (2) cannot be locked; it must remain pressed throughout operation. Note: Do not slow down the power tool by activating the front brake (4).
Run-Out Brake/Front Brake
The power tool is fitted with two protective devices:
The run-out brake slows down the saw chain after the on/off switch (2) is released.
The front brake is a protective mechanism that is triggered via the lever for activating the front brake (4) if the power tool kicks back or the on/off switch fails. The saw chain stops immediately.
Perform a function test from time to time. Push the lever for activating the front brake (4) forwards (position ) and briefly switch on the power tool. The saw chain must not start up. To unlock the front brake again, pull the lever for ac-tivating the front brake (4) back again (position ).
BOSCH GAC 250 Professional Concrete Block Saw 6 Do not carry the power tool by the lever for activating the front brake.

Working with the Power Tool

Before Cutting
The following checks must be performed before starting op-eration and regularly during sawing:

Is the power tool in a safe state?
Is the saw chain tensioned and sharpened correctly? Dur-ing sawing, check the chain tension regularly every ten minutes. Particularly when using new saw chains, in-creased extension should be expected initially. The state of the saw chain greatly influences the sawing perform-ance. Only sharp saw chains protect against overload.
Is the front brake released and its function ensured?
Are you wearing the required protective equipment? Use safety goggles, a dust mask and hearing protection. It is recommended that you wear additional protective equip-ment for your head, hands, legs and feet. Wearing suit-able protective clothing reduces the risk of injury from fly-ing cut material and the saw chain accidentally coming into contact with an object.

Saw Kickback
A saw kickback is the sudden uncontrolled movement and kickback of the running power tool, which can occur if the tip of the chain bar comes into contact with the material to be sawn or if the chain jams.
If a kickback occurs, the power tool may respond unpredict-ably and cause severe injuries to the operator or bystanders in the cutting area.
Particular care must be taken for lateral, bevel and rip cuts because the stop (10) cannot be applied.
To prevent saw kickbacks:

Position the power tool so that it is as flat as possible.
Never work with a loose, extended or heavily worn saw chain.
Never saw above shoulder height.
Never saw using the tip of the chain bar.
Always hold the power tool firmly with both hands.
Always use a Bosch saw chain for autoclaved aerated con-crete (accessory).
Use the stop (10) as a lever.
Make sure that the chain tension is correct.

General Behaviour

Always hold the power tool firmly with both hands, with your left hand on the front handle and your right hand on the rear handle. Always grasp the handles with your thumb and fin-ger. Always guide the mains cable to the rear and keep it out-side the area of the saw chain and material to be sawn.
Ensure you always have a secure footing when operating the power tool.Hold the power tool slightly to the right of your body.
The saw chain must be running at full speed before coming into contact with the autoclaved aerated concrete. To do this, use the stop (10) to support the power tool on the auto-claved aerated concrete. During sawing, use the stop as a lever.
When sawing heavier autoclaved aerated concrete blocks, reposition the stop at a lower point. To do this, pull the power tool back to release the stop and reposition it at a lower point. Do not remove the power tool from the cut.
Do not press on the saw chain with force, let it run by using the stop (10) to create a slight leverage pressure.
Never operate the power tool with extended arms. Do not at-tempt to operate the saw in hard-to-reach places or when standing on a ladder. Never saw above shoulder height.
The best sawing results are achieved when the chain speed is not reduced due to overload.
Be careful at the end of the saw cut. As soon as the power tool has cut through, the weight force will change unexpec-tedly. There is a risk of injury to legs and feet.
Only remove the power tool from the cut with the saw chain running.
BOSCH GAC 250 Professional Concrete Block Saw 9

Sawing Autoclaved Aerated Concrete

When sawing autoclaved aerated concrete, refer to the fol-lowing safety regulations:
Set down the autoclaved aerated concrete as shown in the figure and support it such that the cut does not close and the saw chain jams.
Before sawing, set up shorter autoclaved aerated concrete structures and secure them in place.
Only saw objects made of autoclaved aerated concrete. Avoid coming into contact with stones and nails because they may be hurled upwards and damage the saw chain or cause serious injuries to the user or bystanders.
Do not bring the running power tool into contact with wire fencing or the ground.
Exercise particular caution when making rip cuts because the stop (10) cannot be used. Guide the power tool at a shal-low angle in order to avoid saw kickbacks. BOSCH GAC 250 Professional Concrete Block Saw
8

Troubleshooting

The following table shows fault symptoms and how you can remedy the problem if your power tool does not work properly. If this does not enable you to locate and rectify the problem, contact your service workshop.
Important: Before troubleshooting, switch off the power tool and pull out the mains plug. BOSCH GAC 250 Professional Concrete Block Saw
18

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 in-stall a residual current device (RCD) upstream.

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.
Note: Perform the following maintenance work regularly to ensure long and reliable use.
Check whether the covers and protective devices are un-damaged and fitted correctly. Before use, carry out any re-quired maintenance or repair work.
Regularly inspect the power tool for obvious defects, such as a loose, dislodged or damaged saw chain, a loose fixing and worn or damaged components.
Replacing the Saw Chain and Sprocket Wheel
Replace the saw chain and sprocket wheel with original Bosch spare parts or have these parts replaced at your authorised after-sales service centre for Bosch power tools.
After Use/Storage
Place the chain guard (7) on the chain bar (9) in order to prevent injuries.
The saw chain (8) may become blunt from unintentional im-pacts or scratches.
Clean the moulded plastic housing of the power tool using a soft brush and a clean cloth. Do not use water or any solvents or polishes. Remove all of the dirt, particularly any dirt in the motor’s ventilation slots.
After an application time of 1–3 hours, remove the cover (12), the chain bar (9) and the saw chain (8) and clean them using a brush.
If the power tool is to be stored for a prolonged period of time, clean the saw chain (8) and the chain bar (9).
Store the power tool in a safe, dry place out of the reach of children.
Do not place any other objects on the power tool.
Do not make any alterations to the power tool. Unreliable alterations may compromise the safety of your power tool and lead to increased noise and vibrations.
After-Sales Service and Application Service
Our after-sales service responds to your questions concern-ing 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.