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1 Information about the documentation
1.1 About this documentation
• Read this documentation before initial operation or use. This is a is a prerequisite for safe, trouble-free
handling and use of the product.
• Observe the safety instructions and warnings in this documentation and on the product.
• Always keep the operating instructions with the product and make sure that the operating instructions
are with the product when it is given to other persons.
1.2 Explanation of symbols used
1.2.1 Warnings
Warnings alert persons to hazards that may occur when handling or using the product. The following signal
words are used in combination with a symbol:
DANGER! Draws attention to an imminent hazard that will lead to serious personal injury or
fatality.
WARNING! Draws attention to a potential hazard that could lead to serious personal injury or
fatality.
CAUTION! Draws attention to a potentially dangerous situation that could lead to minor personal
injury or material damage.
1.2.2 Symbols in the documentation
The following symbols are used in this document:
Read the operating instructions before use
Instructions for use and other useful information
1.2.3 Symbols in the illustrations
The following symbols are used in illustrations:
These numbers refer to the corresponding illustrations found at the beginning of these operating
instructions.
The numbering reflects the sequence of operations shown in the illustrations and may deviate
from the steps described in the text.
Item reference numbers are used in the overview illustration and refer to the numbers used in
the key in the product overview section.
This symbol is intended to draw special attention to certain points when handling the product.
1.3 Product-dependent symbols
1.3.1 Symbols on the product
The following symbols are used on the product:
Wear eye protection.
Revolutions per minute
Revolutions per minute
Rated speed
Diameter
Protection class II (double-insulated)
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1.4 Product information
Hilti products are designed for professional use and may be operated, serviced and maintained only by
trained, authorized personnel. This personnel must be informed of any particular hazards that may be
encountered. The product described and its ancillary equipment may present hazards when used incorrectly
by untrained personnel or when used not as directed.
The type designation and serial number are printed on the rating plate.
▶ Write down the serial number in the table below. Always quote this information when you contact a Hilti
representative or Hilti Service to enquire about the product.
Product information
Angle grinder AG 125-15DB
Generation 04
Serial no.
2 Safety
2.1 General power tool safety warnings
WARNING
Read all safety warnings and all instructions. 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.
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 surfaces, such as pipes, radiators, ranges and
refrigerators. 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 electric shock.
▶ Do not abuse the cord. Never use the cord for carrying, pulling or unplugging the power tool. Keep
cord away from heat, oil, sharp edges or moving parts. Damaged or entangled cords increase the
risk of electric shock.
▶ When operating a power tool outdoors, use an extension cord suitable for outdoor use. Use of a
cord suitable for outdoor use reduces the risk of electric shock.
▶ If operating a power tool in a damp location is unavoidable, use a residual current device (RCD)
protected 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 inattention while operating power tools may result in serious personal 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 injuries.
▶ Prevent unintentional starting. Ensure the switch is in the off‐position before connecting to power
source, picking up or carrying the tool. Carrying power tools with your finger on the switch or
energising power tools that have the switch on invites accidents.
▶ Remove any adjusting key or wrench before turning the power tool on. A wrench or a key left
attached to a rotating part of the power tool may result in personal injury.
▶ Do not overreach. Keep proper footing and balance at all times. This enables better control of the
power tool in unexpected situations.
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▶ Dress properly. Do not wear loose clothing or jewellery. 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 extraction and collection facilities, ensure these
are connected and properly used. Use of dust collection can reduce 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 designed.
▶ 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 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 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 maintained 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 account the working conditions and the work to be performed. Use of the power tool for
operations different from those intended could result in a hazardous situation.
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.
2.2 General safety instructions applicable to grinding, sanding, wire brushing and cutting operations:
▶ This power tool is designed to be used for grinding, sanding and cutting. Observe all safety
instructions, other 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.
▶ This power tool is not suitable for use with wire brushes or for polishing. Use of the power tool for
purposes for which it is not intended may be hazardous and cause injury.
▶ Do not use accessories which are not specially designed and recommended for use with this
power tool by the power tool manufacturer. Just because the accessory can be attached to your
power tool, it does not assure safe operation.
▶ The rated speed of rotation of the accessory must be at least equal to the maximum speed stated
on the power tool. Accessories rotating at a speed higher than their rated speed may break and fly
apart.
▶ The outside diameter and thickness of the accessory must comply with the dimensions specified
for the power tool. Incorrectly sized accessories cannot be adequately guarded or controlled.
▶ Accessories with a threaded bushing must fit the drive spindle thread exactly. In the case of
accessories fitted by way of a mounting flange, the diameter of the mounting hole in the accessory
must match the diameter of the mounting flange. Accessories that cannot be mounted exactly on the
power tool will run out of round and cause high vibration, possibly leading to loss of control of the power
tool.
▶ Do not use a damaged accessory. Before use, check accessories such as abrasive discs for chips
and cracks, check backing pads for cracks, tears or excessive wear, and check wire brushes for
loose or broken wires. If the power tool or accessory is dropped, inspect it for damage or use an
undamaged accessory. After checking and fitting an accessory, position yourself and bystanders
out of the plane of rotation of the rotating accessory and run the power tool at maximum no-load
running speed for one minute. Damaged accessories will normally break during this test period.
▶ Wear personal protective equipment. Depending on the application, use a face shield, safety
goggles or protective glasses. As appropriate, wear a dust mask, hearing protection, protective
gloves and a workshop aproncapable of stopping small abrasiveparticles or workpiece fragments.
The eyes must be protected from flying objects or fragments resulting from use of the power tool. The
dust mask or respirator must be capable of filtering out dust particles resulting from use of the power
tool. Prolonged exposure to high-intensity noise may cause hearing loss.
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▶ Keep bystanders a safe distance away from the working area. Anyone entering the working area
must wear personal protective equipment. Fragments of the workpiece or of a broken accessory tool
may fly off and cause injury beyond the immediate working area.
▶ Hold the power tool only by the insulated gripping surfaces when performing an operation where
the accessory tool may contact hidden wiring or the power tool’s own supply cord. If the accessory
tool comes into contact with a live wire, metal parts of the power tool can also become live, resulting in
an electric shock.
▶ Keep the supply cord clear of rotating accessories. If you lose control of the power tool, the supply
cord may be cut through or snagged and your hand or arm could be pulled toward the rotating accessory.
▶ Never lay the power tool down until the accessory comes to a complete stop. The rotating accessory
may come into contact with the surface, possibly causing you to loose control of the power tool.
▶ Do not run the power tool while carrying it at your side. Accidental contact with the rotating accessory
could snag your clothing, pulling the accessory toward your body with a risk of injury.
▶ Regularly clean the power tool’s air vents. The motor’s fan will draw the dust inside the housing and
an excessive accumulation of metal particles 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. Use of water or other liquid coolants may result
in a risk of electric shock.
Kickback and the appropriate safety instructions
Kickback is a sudden reaction to a pinched or snagged rotating disc, 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 direction of rotation at the
point of binding.
For example, if an abrasive disc is snagged or pinched by the workpiece, the edge of the disc entering the
pinch point can dig into the surface of the material causing the disc to climb out or kick back. The disc may
either jump toward or away from the operator, depending on the disc’s direction of movement at the point
of pinching. Abrasive discs may also break under these conditions.
Kickback is the result of power tool misuse and/or incorrect operating procedures or conditions. It can be
avoided by taking the proper precautions as described below.
▶ Maintain a firm grip on the power tool and position your body and arm to allow you to resist
kickback forces. Always use the 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 bring your hand close to a 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 the direction opposite to the disc’s movement at the point of snagging.
▶ Take special care when working on corners, sharp edges, etc. Avoid bouncing and snagging the
accessory. Corners, sharp edges or bouncing tend to snag the rotating accessory. This causes loss of
control or kickback.
▶ Do not attach a saw chain or toothed saw blade. Devices of this kind cause frequent kickback and
loss of control of the power tool.
Safety instructions specific to grinding and abrasive cutting operations:
▶ Use only disc types approved for use with your power tool and the guard designed for use with
the selected disc. Discs for which the power tool was not designed cannot be adequately guarded and
are unsafe.
▶ Offset (dished) grinding discs must be fitted so that their grinding surface does not project beyond
the edge of the guard. Incorrectly fitted grinding discs, the surface of which projects beyond the edge
of the guard, cannot be adequately guarded.
▶ The guard must be securely mounted on the power tool and, for maximum safety, it must be
adjusted so that as little as possible of the grinding disc is exposed on the side facing the operator.
The guard helps to protect the operator from flying fragments, inadvertent contact with the disc and
sparks that could cause the operator’s clothing to catch fire.
▶ Discs may be used only for the recommended applications. For example: Do not grind with the
side of a cutting disc. Abrasive cutting discs are intended for peripheral abrasive cutting. Lateral forces
applied to these discs may cause them to shatter.
▶ Always use an undamaged disc mounting flange of the correct size and shape for the selected
disc. Proper flanges support the disc, thus reducing the possibility of disc breakage. Flanges for cutting
discs may be different from flanges for grinding discs.
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▶ Do not use worn-down grinding discs from larger power tools. Discs intended for larger power tools
are not suitable for the higher speed of a smaller power tool and may break or shatter as a result.
Additional safety instructions for abrasive cutting operations:
▶ Do not “jam” the cutting disc or apply excessive pressure. Do not attempt to make excessively
deep cuts. Overstressing the disc increases loading and susceptibility to twisting or binding of the disc
in the cut and the possibility of kickback or disc breakage.
▶ Do not position your body in front of or behind the rotating disc. When the disc, at the point of
operation, is moving away from your body, possible kickback may propel the rotating disc and the power
tool directly toward you.
▶ When the disc is binding or when interrupting a cut for any reason, switch off the power tool and
hold the power tool motionless until the disc comes to a complete stop. Never attempt to remove
the cutting disc from the cut while the disc is in motion otherwise kickback may occur. Investigate
and take corrective action to eliminate the cause of the disc binding.
▶ Do not restart the cutting operation in the workpiece. Let the disc reach full speed and carefully
reenter the cut. The disc may bind, walk up or kick back if the power tool is restarted with the disc in
the workpiece.
▶ Support panels or oversized workpieces to minimize the risk of disc 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 disc.
▶ Use extra caution when making pocket cuts in existing walls or other blind areas. The protruding
disc may cut gas or water pipes, electrical wiring or objects that can cause kickback.
Special safety instructions for sanding operations:
▶ Do not use oversized sanding discs. Follow the manufacturer’s specifications regarding sanding
disc size. Sanding discs that project beyond the edge of the sanding pad may cause tearing of the
sanding disc, stalling of the power tool or kickback, possibly resulting in injury.
2.3 Additional safety instructions
Personal safety
▶ Use the product only when it is in technically faultless condition.
▶ Never tamper with or modify the tool in any way.
▶ Always hold the power tool with both hands on the handles provided. Keep the handles clean and dry.
▶ Avoid touching rotating parts – risk of injury!
▶ Wear suitable protective glasses, a hard hat, ear protection, protective gloves and light respiratory
protection while using the power tool.
▶ Before beginning the work, check the hazard classification of the dust that will be produced. Use an
industrial vacuum cleaner with an officially approved protection class in compliance with the locally
applicable dust protection regulations. Dust from materials such as lead-based paint, certain types of
wood and concrete/masonry/stone containing quartz, minerals or metal may be harmful to health.
▶ Make sure that the workplace is well ventilated and, where necessary, wear a respirator appropriate for
the type of dust generated. Contact with or inhalation of the dust may cause allergic reactions and/or
respiratory or other diseases among operators or bystanders. Certain kinds of dust are classified as
carcinogenic such as oak and beech dust, especially in conjunction with additives for wood conditioning
(chromate, wood preservative). Material containing asbestos may be handled only by specialists.
▶ Take breaks between working and do physical exercises to improve the blood circulation in your fingers.
Exposure to vibration during long periods of work can lead to disorders of the blood vessels and nervous
system in the fingers, hands and wrists.
Electrical safety
▶ Before beginning work, check the working area for concealed electric cables or gas and water pipes.
External metal parts of the power tool may give you an electric shock if you damage an electric cable
accidentally.
▶ Do not touch the supply cord or extension cord if it is damaged while working. Disconnect the mains
plug from the power outlet. Check the tool’s supply cord at regular intervals and have it replaced by Hilti
Service if damage is found. Check extension cords at regular intervals and replace them if found to be
damaged.
Using and handling power tools with care
▶ Do not use cutting discs for grinding.
▶ Remove the clamping flange from the arbor before fitting a threaded accessory tool.
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▶ Tighten the accessory tool and flange securely. If the accessory tool and flange are not tightened
securely, the accessory tool may work loose from the arbor due to the braking effect of the motor after
switching off.
▶ Comply with the manufacturer's instructions for handling and storing grinding discs.
3 Description
3.1 Overview of the product 1
@
Spindle lockbutton
;
Air vents
=
Vibration-absorbing side handle
%
Wrench
&
Clamping nut
(
Cutting disc / grinding disc
)
Clamping flange with O-ring
+
Guard
§
On/off switch
/
Switch-on interlock release button
:
Spindle
∙
Quick locking system
$
Guard release button
£
Threaded bushing for handle
3.2 Intended use
The product described is a hand-held electric angle grinder. It is designed for cutting, grinding and sanding
metal and mineral materials without use of water.
The tool may be operated only when connected to a power supply providing a voltage and frequency in
compliance with the information given on its rating plate.
• The power tool may be used for cutting, slitting and grinding mineral materials only when equipped with
the corresponding guard (optional accessory).
• A dust removal hood together with a suitable Hilti vacuum cleaner must be used for working on mineral
materials such as concrete or stone.
3.3 Items supplied
Angle grinder, side handle, standard guard, front cover, clamping flange, clamping nut, wrench, operating
instructions.
You can find other system products approved for your product at your local Hilti Center or online at:
www.hilti.com
3.4 Integrated brake
The integrated brake reduces the time it takes until the accessory tool stops rotating after switching off.
3.5 Starting current limitation
The electronic starting current limiter reduces the starting current drawn by the power tool and thus prevents
the mains fuse blowing. It also allows the power tool to start smoothly, without a jolt.
3.6 Constant-speed electronics
Electronic speed control keeps running speed almost constant irrespective of whether the power tool is
idling or running under load. Constant running speed helps ensure maximum efficiency.
3.7 Active Torque Control (ATC)
The electronics detect potential stalling of the disc and prevent further rotation of the drive spindle by
switching off the tool.
If the ACT system has been triggered, restart the tool. Do this by releasing the on/off switch and then
pressing it again.
Note
If the ATC system malfunctions, the power tool will run only at greatly reduced speed and with greatly
reduced torque. Have the tool checked by Hilti Service.
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3.8 Restart interlock
The power tool does not restart by itself when the on/off switch is locked in the on-position and the power
returns after an interruption in the electric supply. The on/off switch must first be released and then pressed
again to restart.
3.9 Temperature-dependent device protection
The temperature-dependent motor protection system monitors current input and motor temperature and
thus prevents the power tool overheating.
If the motor is overloaded through application of excessive working pressure, the power tool’s performance
drops noticeably or it may stop completely. A standstill should be avoided. No specific value can be given
for the permissible overloading limit for the power tool as it depends on motor temperature.
3.10 Front cover for the disc guard 2
When grinding with straight grinding discs and cutting with cutting discs in metalworking applications,
use the standard guard with front cover.
3.11 DG-EX 125/5" dust hood for grinding (accessory) 3
The grinding system is suitable only for occasional use with diamond cup wheels for grinding mineral
materials.
CAUTION Use of this hood for working on metal is prohibited.
3.12 DC-EX 125/5"C dust hood for cutting (accessory) 4
Use the DC-EX 125/5"C dust hood when cutting masonry and concrete.
CAUTION Use of this hood for working on metal is prohibited.
4 Consumables
Only synthetic resin-bonded, fiber-reinforced discs with a maximum diameter of Ø 125 mm which are
approved for use at a rotational speed of at least 11,500/min and a peripheral speed of 80 m/s may be used.
The maximum grinding disc thickness is 6.4 mm and the maximum cutting disc thickness is 2.5 mm.
WARNING! When cutting or slitting with cutting discs, always use the standard guard with additional
cover plate.
Discs
Application Designation Material
Abrasive cutting disc Cutting, slitting ACD Metal
Diamond cutting disc Cutting, slitting DC-TP, DC-D (SPX,
SP, P)
Mineral
Abrasive grinding disc Rough grinding AGD, AFD, AND Metal
Diamond grinding disc Rough grinding DG-CW (SPX, SP, P) Mineral
Abrasive resin-fiber disc Rough grinding AP-D Metal
Suitability of discs for the equipment used
Item Equipment ACD AGD,
AFD, AND
DG-CW
(SPX, SP,
P)
DC-TP,
DC-D (SPX,
SP, P)
AP-D
A Guard X X X X X
B Front cover (in combina-
tion with A)
X — — X —
C DG-EX 125/5" dust hood
for grinding
— — X — —
D DC-EX 125/5"C dust
hood for cutting (only in
conjunction with A)
— — — X —
E Side handle X X X X X
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Item Equipment ACD AGD,
AFD, AND
DG-CW
(SPX, SP,
P)
DC-TP,
DC-D (SPX,
SP, P)
AP-D
F DCBG 125 hoop handle
(optional for E)
X X X X X
G Clamping nut X X X X —
H Clamping flange X X X X —
I Clamping nut for abra-
sive resin-fiber disc
(M14x1.5)
— — — — X
J Support plate — — — — X
5 Technical data
5.1 Angle grinder
Note
When powered by a generator or transformer, the generator or transformer’s power output must be at
least twice the rated input power shown on the rating plate of the power tool. The operating voltage of
the transformer or generator must always be within +5% and -15% of the rated voltage of the power
tool.
The information given applies to a rated voltage of 230 V. The data may vary in the event of deviations
from the rated voltage and for country-specific versions. Please refer to the power tool’s type
identification plate for details of its voltage, frequency, current and input power ratings.
AG 125-15DB
Rated power input
1,500 W
Rated speed
11,500 /min
Maximum disc diameter
125 mm
Thread diameter
M14x1.5
Thread length
22 mm
Weight in accordance with EPTA procedure 01/2003
2.7 kg
5.2 Noise information and vibration values determined in accordance with EN 60745
The sound pressure and vibration values given in these instructions have been measured in accordance with
a standardized test and may be used to compare one power tool with another. They may be used for a
preliminary assessment of exposure.
The data given represents the main applications of the power tool. However, if the power tool is used for
different applications, with different accessory tools or is poorly maintained, the data may vary. This may
significantly increase exposure over the total working period.
An accurate estimation of exposure should also take into account the times when the power tool is switched
off, or when it is running but not actually being used for a job. This may significantly reduce exposure over
the total working period.
Identify additional safety measures to protect the operator from the effects of noise and/or vibration, for
example: Maintaining the power tool and accessory tools, keeping the hands warm, organization of work
patterns.
Noise emission values determined in accordance with EN 60745-2-3
AG 125-15DB
Sound (power) level (LWA)
102 dB(A)
Emission sound pressure level (LpA)
91 dB(A)
Uncertainty for the sound pressure level
(KpA)
3 dB(A)
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Total vibration (vector sum of three directions), measured in accordance with EN 60745-2-3
Other applications, such as cutting, may produce vibration values that deviate from the given values.
AG 125-15DB
Surface grinding with the
vibration-absorbing side handle (a
h,AG
)
4.4 m/s²
Sanding (a
h,DS
)
3.0 m/s²
Uncertainty (K)
1.5 m/s²
6 Before use
CAUTION
Risk of injury. The accessory tool may be hot or have sharp edges.
▶ Wear protective gloves when fitting, removing or adjusting the accessory tool or other parts and
when troubleshooting.
6.1 Fitting the side handle
▶ Screw the side handle into one of the threaded bushings provided.
6.2 Guard
▶ Observe the instructions for fitting the applicable guard.
6.2.1 Fitting the guard 5
Note
The keying on the guard ensures that only a guard designed for use with the power tool can be fitted.
The keyed locating lug also prevents the guard from coming into contact with the tool.
1. Fit the guard onto the drive spindle collar so that the two triangular marks on the guard and on the power
tool are in alignment.
2. Press the guard onto the drive spindle collar.
3. Press the guard release button and then rotate the guard until it engages in the desired position.
◁ The guard release button jumps back.
6.2.2 Adjusting the guard 6
▶ Press the guard release button and then rotate the guard until it engages in the desired position.
6.2.3 Removing the guard
1. Press the guard release button and then rotate the guard until the two triangular marks on the guard and
the power tool are in alignment.
2. Lift off the guard.
6.3 Fitting or removing the front cover 7
1. Position the front cover with the closed side on the standard guard and push it on until it engages.
2. To remove it, release the catch for the front cover and then lift the front cover away from the standard
guard.
6.4 Fitting or removing the discs
CAUTION
Risk of injury. The accessory tool may be hot.
▶ Wear protective gloves when changing the accessory tool.
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Note
Diamond discs must be replaced when their cutting or grinding performance drops significantly. This
generally is the case when the diamond segments reach a height of less than 2 mm (1/16").
Other discs must be replaced when their cutting performance drops significantly or other parts of the
angle grinder (not the disc) come into contact with the material you are working on.
Abrasive discs must be replaced when their expiry date has been reached.
6.4.1 Fitting the grinding disc 8
1. Disconnect the mains plug from the power outlet.
2. Check that the O-ring is in place in the clamping flange and that it is undamaged.
Result
The O-ring is damaged.
There is no O-ring in the clamping flange.
▶ Fit a new clamping flange with O-ring.
3. Fit the clamping flange onto the drive spindle.
4. Fit the grinding disc.
5. Screw on the clamping nut corresponding to the type of accessory tool fitted.
6. Press the spindle lockbutton and hold it in this position.
7. Use the pin wrench to tighten the clamping nut securely, then release the spindle lockbutton and remove
the wrench.
6.4.2 Removing the grinding disc
1. Disconnect the mains plug from the power outlet.
CAUTION
Risk of breakage and irreparable damage. If the spindle lockbutton is pressed while the spindle is
rotating, this may cause the accessory tool to work loose or detach from the power tool.
▶ Press the spindle lockbutton only when the spindle has stopped rotating.
2. Press the spindle lockbutton and hold it in this position.
3. Release the clamping nut by gripping it with the pin wrench and turning the nut counterclockwise.
4. Release the spindle lockbutton and remove the grinding disc.
6.5 Fitting the abrasive resin-fiber disc 9
1. Disconnect the mains plug from the power outlet.
2. Fit the side handle. → page 23
3. Fit the guard. → page 23
4. Fit the support plate and the abrasive resin-fiber disc, screw on the clamping nut and tighten it securely.
5. Press the spindle lockbutton and hold it in this position.
6. Use the pin wrench to tighten the clamping nut securely, then release the spindle lockbutton and remove
the wrench.
7 Operation
7.1 Grinding
CAUTION
Risk of injury. The accessory tool may suddenly stick or stall.
▶ Use the power tool with the side handle (or optional hoop grip) fitted and always hold the power
tool securely with both hands.
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7.1.1 Cutting
▶ When cutting, apply moderate feed pressure and do not tilt the power tool or the cutting disc (when
working, hold at approx. 90° to the surface being cut).
Note
For best results when cutting profiles and square tube, start cutting at the smallest cross section.
7.1.2 Rough grinding
▶ Move the power tool to and fro while maintaining a 5° to 30° angle of attack and applying moderate
pressure.
◁ This will avoid overheating and discoloration of the workpiece and help ensure an even surface finish.
7.2 Switching on and off
7.2.1 Switching on 10
Note
The on/off switch with built-in safety lock allows the user to check the switch function and prevents
inadvertent starting of the power tool.
1. Plug the supply cord into the power outlet.
2. Slide the safety lock forward to unlock the on/off switch.
3. Press the on/off switch as far as it will go.
◁ The motor runs.
7.2.2 Switching off
▶ Release the on/off switch.
◁ The safety lock jumps back automatically into the locked position and the motor stops.
8 Care and maintenance
Note
To help ensure safe and reliable operation, use only genuine Hilti spare parts and consumables. Spare
parts, consumables and accessories approved by Hilti for use with the product can be found at your
local Hilti Center or online at: www.hilti.com
8.1 Care of the product
DANGER
Electric shock due to breakdown of protective insulation. When working on metal under extreme
conditions, conductive dust may accumulate inside the power tool, thereby adversely affecting the
protective insulation.
▶ Use a stationary dust extraction system when working under extreme conditions.
▶ Clean the air vents frequently.
▶ Use a ground fault circuit interrupter (PRCD) in the electric power supply line to the power tool.
WARNING
Electrical hazards. Improper repairs to electrical parts may lead to serious injuries.
▶ Electrical parts may be repaired only by trained electrical specialists.
▶ Never operate the product when the air vents are blocked. Clean the air vents carefully using a dry brush.
Do not allow foreign objects to enter the interior of the product.
▶ Keep the product, especially its grip surfaces, clean and free from oil and grease. Do not use cleaning
agents containing silicone.
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26 English
▶ Clean the outer surfaces of the tool with a slightly damp cloth at regular intervals. Do not use a spray,
steam pressure cleaning equipment or running water for cleaning.
Note
Frequent work on conductive materials (e.g. metal, carbon fiber) may make shorter maintenance
intervals necessary. Take your individual workplace risk assessment into account.
8.2 Checks after care and maintenance work
▶ After carrying out care and maintenance, check that all protective and safety devices are fitted and that
they function faultlessly.
9 Transport and storage
▶ Do not transport the power tool with an accessory tool fitted to it.
▶ Always unplug the supply cord before storing the power tool.
▶ Store the product in a dry place where it cannot be accessed by children or unauthorized persons.
▶ After long periods of transport or storage, check the power tool for damage before use.
10 Troubleshooting
If the trouble you are experiencing isn’t listed in this table or you are unable to remedy the problem by
yourself, please contact Hilti Service.
Trouble or fault Possible cause Action to be taken
The tool doesn’t start. Interruption in the electric supply. ▶ Plug in another power tool or
appliance and check whether it
works.
The supply cord or plug is defective.
▶ Have the supply cord and plug
checked by a trained electrical
specialist and replaced if
necessary.
The carbon brushes are worn. ▶ Have the power tool checked by
a trainedelectrical specialist and
the carbon brushes replaced if
necessary.
The tool doesn’t work. The tool has been overloaded. ▶ Release the on/off switch and
then press it again. Then allow
the power tool to run under no
load for approx. 30 seconds.
The tool doesn’t achieve full
power.
The extension cord conductor
cross section (gauge) is inadequate.
▶ Use an extension cord with
an adequate conductor cross
section.
11 Disposal
Most of the materials from which Hilti tools and appliances are manufactured can be recycled. The
materials must be correctly separated before they can be recycled. In many countries, your old tools,
machines or appliances can be returned to Hilti for recycling. Ask Hilti Service or your Hilti representative
for further information.
▶ Disposal of electric tools or appliances together with household waste is not permissible.
12 Manufacturer’s warranty
▶ Please contact your local Hilti representative if you have questions about the warranty conditions.
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13 EC declaration of conformity
Manufacturer
Hilti Aktiengesellschaft
Feldkircherstrasse 100
9494 Schaan
Liechtenstein
We declare, on our sole responsibility, that this product complies with the following directives and standards.
Designation Angle grinder
Type designation AG 125-15DB
Generation 04
Year of design 2016
Applicable directives: • 2006/42/EC
• 2014/30/EU
• 2011/65/EU
Applicable standards: • EN 60745-1, EN 60745-2-3
• EN ISO 12100
Technical documentation filed at: • Hilti Entwicklungsgesellschaft mbH
Zulassung Geräte
Hiltistraße 6
86916 Kaufering
Germany
Schaan, 10/2016
Paolo Luccini
(Head of BA Quality & Process Management /
Business Area Electric Tools & Accessories)
Tassilo Deinzer
(Executive Vice President / Business Unit Power
Tools & Accessories)
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