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DG 150
DPC 20

Original operating instructions

Information about the documentation

About this documentation

  • Read this documentation before initial operation or use. This 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.

Explanation of symbols used


Warnings alert you to hazards that can occur when you are handling or using the product. The following signal words are used in combination with a symbol:
Image alternative DANGER! Draws attention to imminent danger leading to serious injury or fatality.
Image alternative WARNING! Draws attention to a potential threat of danger that can lead to serious injury or fatality.
Image alternative CAUTION! Draws attention to a potentially dangerous situation that can lead to minor injury or damage to the equipment or other property.


The following symbols are used:
Image alternative Read the operating instructions before use
Image alternative Instructions for use and other useful information
Image alternative Protection class II (double-insulated)
Image alternative Diameter
Image alternative Rated speed under no load
Image alternative Revolutions per minute
Image alternative Revolutions per minute


The following symbols are used in illustrations:
Image alternative These numbers refer to the corresponding illustrations found at the beginning of these operating instructions.
Image alternative The numbering reflects the sequence of operations shown in the illustrations and may deviate from the steps described in the text.
Image alternative Item reference numbers are used in the overview illustration and refer to the numbers used in the key in the product overview section.
Image alternative This symbol is intended to draw special attention to certain points when handling the product.

Product information

Hilti products are designed for professional users and only trained, authorized personnel are permitted to operate, service and maintain the products. This personnel must be informed of any particular hazards that may be encountered. The product and its ancillary equipment can present hazards if used incorrectly by untrained personnel or if used not in accordance with the intended use.
  • Write down the serial number in the table below. You will be required to state the product details when contacting Hilti Service or your local Hilti organization to inquire about the product.
Product information
Product information
Product information
DG 150
Serial no.

Product information
Power conditioner
DPC 20
Serial no.

Declaration of conformity

We declare, on our sole responsibility, that the product described here complies with the applicable directives and standards. A copy of the declaration issued by the certification department can be found at the end of this documentation.
The technical documentation is filed here:
Hilti Entwicklungsgesellschaft mbH | Tool Certification | Hiltistrasse 6 | 86916 Kaufering, Germany


Safety instructions

General power tool safety warnings

Image alternative 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.
The term “power tool” in the warnings refers to your mains-operated (corded) power tool or battery-operated (cordless) 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 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 and/or battery pack, 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.
  • 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 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 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.
  • 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 common for grinding, sanding, wire brushing, polishing or abrasive cutting-off operations:

DG 150
  • This power tool is intended to function as a grinder. Read all safety warnings, instructions, illustrations and specifications provided with this power tool. Failure to follow all instructions listed below may result in electric shock, fire and/or serious injury.
  • Operations such as sanding, wire brushing, polishing or cutting are not recommended to be performed with this power tool. Operations for which the power tool was not designed may create a hazard and cause personal injury.
  • Do not use accessories which are not specifically designed and recommended by the tool manufacturer. Just because the accessory can be attached to your power tool, it does not assure safe operation.
  • The rated speed of the accessory must be at least equal to the maximum speed marked on the power tool. Accessories running faster than their rated speed can break and fly apart.
  • The outside diameter and the thickness of your accessory must be within the capacity rating of your power tool. Incorrectly sized accessories cannot be adequately guarded or controlled.
  • 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 inspect 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 install an undamaged accessory. After inspecting and installing an accessory, position yourself and bystanders away from the plane of the rotating accessory and run the power tool at maximum no-load speed for one minute. Damaged accessories will normally break apart during this test time.
  • Wear personal protective equipment. Depending on application, use face shield, safety goggles or safety glasses. As appropriate, wear dust mask, hearing protectors, gloves and workshop apron capable of stopping small abrasive or workpiece fragments. The eye protection must be capable of stopping flying debris generated by various operations. The dust mask or respirator must be capable of filtrating particles generated by your operation. Prolonged exposure to high intensity noise may cause hearing loss.
  • Keep bystanders a safe distance away from 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 exposed metal parts of the power tool "live" and could give the operator an electric shock.
  • Position the cord clear of the spinning accessory. If you lose control, the cord may be cut or snagged and your hand or arm may be pulled into the spinning 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 control.
  • Do not run the power tool while carrying it at your side. Accidental contact with the spinning accessory could snag your clothing, pulling the accessory into your body.
  • Regularly clean the power tool’s air vents. The motor’s fan will draw the dust inside the housing and excessive accumulation of powdered metal may cause electrical hazards.
  • Do not operate the power tool near flammable materials. Sparks could ignite these materials.
  • Do not use accessories that require liquid coolants. Using water or other liquid coolants may result in electrocution or shock.
Kickback and related warningsKickback is a sudden reaction to a pinched or snagged rotating wheel, backing pad, brush or any other accessory. Pinching or snagging causes rapid stalling of the rotating accessory which in turn causes the uncontrolled power tool to be forced in the direction opposite 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 direction of the wheel’s movement at the point of pinching. Abrasive wheels may also break under these conditions.
Kickback is the result of power tool misuse and/or incorrect operating procedures or conditions and can be avoided by taking proper precautions as given below.
  • Maintain a firm grip on the power tool and position your body and arm to allow you to resist kickback forces. Always use auxiliary handle, if provided, for maximum control over kickback or torque reaction during start-up. The operator can control torque reactions or kickback forces, if proper precautions are taken.
  • Never place your hand near the rotating accessory. 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 kickback and loss of control.

Additional safety instructions

Personal safety
  • Do not tamper with or attempt to make alterations to the device.
  • Keep the grips dry, clean and free from oil and grease.
  • Make sure that the side handle is fitted correctly and tightened securely. Always hold the tool firmly with both hands on the grips provided.
  • Take breaks between working and do relaxation and finger exercises to improve the blood circulation in your fingers.
  • The power tool is not intended for use by debilitated persons who have received no special training.
  • Keep the power tool out of reach of children.
  • Do not touch rotating parts. Switch the power tool on only after it is in position at the workpiece. Touching rotating parts, especially rotating accessory tools, can result in injury.
  • Grinding can produce hazardous grinding dust. Before starting work, check the hazard class of the dust that will be produced by grinding operations. When working with the power tool, whenever possible use a dust extractor 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 can be harmful to health. Contact with or inhalation of the dust can cause allergic reactions and/or respiratory or other diseases among operators or bystanders. Certain kinds of dust such as oakwood and beechwood dust are classified as carcinogenic, especially in conjunction with additives for wood conditioning (chromate, wood preservative). Only specialists are permitted to handle material containing asbestos. Use a dust extractor whenever possible. To achieve a high level of dust collection, use a suitable dust extractor. If necessary, wear a respirator appropriate for the type of dust generated. Make sure that the workplace is well ventilated. Comply with national regulations applicable to the materials you will be working with.
  • Before starting grinding work, carefully remove all protruding parts such as nails, screws, etc.
  • Grinding can produce flying sparks. Make sure that no-one is endangered.
Power tool use and care
  • Secure the workpiece. Use clamps or a vice to hold the workpiece in position. The workpiece is thus held more securely than by hand and both hands remain free to operate the power tool.
  • Always before starting work, and this also applies after each break, check that the accessory tool is secure.
Electrical safety
  • Before beginning work, check the working area (e.g. using a metal detector) to ensure that no concealed electric cables or gas and water pipes are present. External metal parts on the power tool can become live, for example if you inadvertently damage electric wiring. This presents a serious risk of electric shock.
  • Never disconnect the plug from the DPC 20 power conditioner while the DG 150 grinder is in operation under load.
  • Check the machine’s supply cord at regular intervals and have it replaced by a qualified specialist if found to be damaged. If the machine’s supply cord is damaged it must be replaced with a specially prepared and approved supply cord available from Hilti Customer Service. Check extension cords at regular intervals and replace them if found to be damaged. Do not touch the supply cord or extension cord if it is damaged while working. Disconnect the supply cord plug from the power outlet. Damaged supply cords or extension cords present a risk of electric shock.
  • Have dirtied or dusty power tools that are used frequently for working on conductive materials checked at regular intervals by Hilti Service. Dust (especially dust from conductive materials) or dampness on the surface of the power tool can, under unfavorable conditions, lead to electric shock.
Personal safety
  • Make sure that the workplace is well ventilated. It is advisable to wear a filter class P2 dust mask.
  • The diamond cup wheel, parts of the guard or the power tool (gear head) can become hot in use. To avoid burns, do not touch these parts unless you are wearing gloves.


Product overview

Image alternative
  1. On/off switch
  2. Side handle
  3. Guard, complete
  4. Clamping band
  5. Clamping lever
  6. LED indicator
  7. Machine supply plug
  8. Speed selector switch (speeds 1 and 2)
  9. Side-handle locking screw
  10. Adjusting screw

Tool components and controls

Image alternative
  1. Pin wrench
  2. Clamping nut
  3. Diamond cup wheel
  4. Lamellar seal, small
  5. Clamping flange
  6. Lamellar seal, large
  7. Retaining ring
  8. Arbor
  9. Locking ring
  10. Guard bottom section
  11. Guard top section
  12. Arbor lockbutton

Tool components, status indicators and controls

Image alternative
  1. LED indicator
  2. Supply cord
  3. Locating lug
  4. Carrying handle
  5. Clip for power cord
  6. Electrical socket with hinged cover
  7. Latching lug

Intended use

The product described is an electrically powered diamond grinder. It is designed for professional use in grinding mineral materials. The DG 150 grinder can be operated only in combination with the DPC 20 power conditioner. Always use a dust extractor to ensure optimum dust removal.

The grinder is designed exclusively for dry abrasive removal of uncoated mineral materials and thin coatings on concrete and similar mineral materials, with a maximum layer thickness of 3 mm (0.12 in).

Possible misuse

Do not use the product may in environments where there is a risk of explosion.
Do not use the product for wet grinding.
Do not use the product to work on hazardous or flammable materials (e.g. asbestos, magnesium, wood).

Items supplied

DG 150 grinder, DPC 20 power conditioner, clamping flange, clamping nut, pin wrench, operating instructions.
Other system products approved for use with this product can be found at your local Hilti Store or online at: | USA:

Technical data

Technical data, DG 150

Rated speed, speed I
4,700 /min
Rated speed, speed II
6,600 /min
Weight of the DG 150 in accordance with EPTA procedure 01/2003
4.1 kg
(9.0 lb)
Protection class (EN 60745 1)
Protection class II (double-insulated)
Quick stop after power OFF
≤ 2 s
Optimum gap between lamellar seal and work surface
0 mm … 1 mm
(0 in … 0.04 in)

Technical data, DPC 20

If the device is 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 device. The operating voltage of the transformer or generator must always be within +5 % and -15 % of the rated voltage of the device.
The information given applies for a rated voltage of 230 V. Actual figures can vary for country-specific versions and if the voltage supply differs. For rated voltage, frequency, input power and rated current, refer to the country-specific type identification plate.

110 V
Rated current
16 A
Power input
1,760 W
Rated frequency
50/60 Hz
Weight of the DPC 20 in accordance with EPTA procedure 01/2003
3.8 kg
(8.4 lb)


Preparations at the workplace

Risk of injury! Inadvertent starting of the product.
  • Unplug the supply cord before making adjustments to the power tool or before changing accessories.
Observe the safety instructions and warnings in this documentation and on the product.

Adjusting the guard

  1. Set the device on the work surface.
  2. Release the clamping lever.
  3. Turn the retaining ring with lamellar seal until the gap between lamellar seal and work surface is correct.
  4. Turn the guard to the desired position.
  5. Close the clamping lever.
    If the guard is not secure when the lever is in the closed position, tighten the clamping band by turning the adjusting screw clockwise with a screwdriver.
    If the guard is too tight to move when the lever is in the open position, slacken the clamping band by turning the adjusting screw counter-clockwise with a screwdriver.

Adjusting the guard for working close to an edge

  1. Release the clamping lever.
  2. Turn the top part of the guard relative to the bottom part until the desired position is reached.
  3. Set the device on the work surface.
  4. Turn the retaining ring with lamellar seal until the gap between lamellar seal and work surface is correct.
  5. Close the clamping lever.
    More dust can escape past the guard when the device is used for working close to an edge.

Adjusting the side handle

  1. Slacken the side handle by turning the securing screw counter-clockwise.
  2. Swing the side handle forward or back to the desired position.
  3. Secure the side handle by turning the securing screw clockwise.

Fitting a diamond cup wheel

  1. Fit the clamping flange onto the spindle with the O-shaped depression facing the tool, so that the clamping flange engages (keyed fit).
  2. Fit the grinding disc onto the centering collar on the clamping flange.
  3. Screw on the clamping nut in a clockwise direction and then use the wrench to tighten it against the resistance of the motor/gearing.

Removing the diamond cup wheel

  1. Press and hold down the arbor lockbutton.
  2. Release the clamping nut by gripping it with the wrench and turning the nut counter-clockwise.
  3. Remove the clamping nut.
  4. Release the arbor lockbutton and remove the diamond cup wheel.

Types of work

Setting the speed of the diamond cup wheel

  1. Use speed I for better dust control when grinding off soft mineral materials, such as paint from cement rendering, and to make the power tool easier to guide when grinding off coatings from soft materials.
  2. Use speed II to apply the full power of the tool when grinding hard mineral materials such as concrete, floor screeding or natural stone.

Switching on

  1. Connect the grinder to an industrial vacuum cleaner.
  2. Plug the grinder's supply cord plug into the power outlet of the DPC 20.
  3. Plug the DPC 20 into the power outlet of the electricity supply.
    • The LED lights green.
  4. Lift the power tool clear of the work surface.
  5. Push the on/off switch forward to the on position (I).
    • The on/off switch engages in the on position (I).

Trying out after fitting a new diamond cup wheel

Risk of injury. Damaged diamond cup wheels can come loose.
  • Do not use a diamond cup wheel if it vibrates; protect the cup wheel against impact, shock loading and grease.
  • Allow the power tool to run for at least 1 minute without load.


  1. Always keep the grinder close to the work surface.
  2. Move the device back and forth.
  3. Apply moderate pressure and do not dig the tool into the material.

Switching off

  1. Press the on/off switch.
    • The on/off switch goes to the off position (0) when released.
  2. Disconnect the supply cord plug from the power outlet.
  3. If an industrial vacuum cleaner was in use, disconnect the hose connection between the device and the industrial vacuum cleaner.

Care of the product

  • Keep the grinder, especially its grip surfaces, clean and free from oil and grease. Do not use cleaning agents containing silicone.
  • Never operate the grinder with the air vents blocked. Clean the air vents carefully using a dry brush. Do not permit foreign matter to penetrate inside the product.
  • Clean the outside of the device at regular intervals with a slightly damp cloth. Do not use a sprayer, steam pressure cleaning equipment or running water for cleaning.

Removing the guard lamellar seal

  1. Remove the diamond cup wheel.
  2. Use a screwdriver to ease the three clamping tongues of the retaining ring over the edge of the guard.
  3. Remove the large lamellar seal from the retaining ring.
  4. Push the tip of a screwdriver into the two slots in the outside of the guard and disengage the small lamellar seal.

Installing the guard lamellar seal

  1. Remove coarse dust from the retaining grooves.
  2. Press the small lamellar seal into the guide in the guard until it engages.
  3. Position the large lamellar seal in the groove of the retaining ring.
  4. Push the retaining ring complete with lamellar seal over the edge of the guard until it engages.


DG 150

Trouble or fault
Possible cause
Action to be taken
The tool can’t be switched on.
Interruption in the electric supply.
  • Slide the on / off switch to the “off” (0) position and then back to the “on” position (I).
The tool doesn’t achieve full power.
Supply voltage is too low.
  • Use a compatible electric supply.
The LED blinks red.
The power tool has overheated.
  • Switch the power tool off and allow it to cool down until the red LED goes out.
A lot of dust escapes from the guard.
No vacuum cleaner is connected.
  • Connect a vacuum cleaner.
The lamellar seal is not flush with the working surface, allowing dust to escape between the guard and the working surface.
  • Adjust the position of the guard relative to the working surface.
The lamellar seal is worn.
  • Replace the lamellar seal.
Suction performance of the vacuum cleaner is too low as the filter is clogged with dirt or dust.
  • If the automatic filter cleaning system is deactivated, activate it and allow the vacuum cleaner to run for 30 seconds.
  • Close the end of the hose with your hand and allow the vacuum cleaner to run for 30 seconds.
  • Use a water hose to rinse the V 20/40 universal filter and the VC 20/40 performance filter. Never beat out the filter against a wall or floor as this may result in microholes that allow dust to pass through.
  • Change the filter.
Suction performance of the vacuum cleaner is too low, as a the wrong filter is fitted.
  • Use the V 20/40 universal filter or the VC 20/40 performance filter when you are picking up water, slurry or other damp material.
  • Use the VC 20/40 performance filter when you are picking up large quantities of mineral dust (e.g. when grinding, slitting or cleaning concrete).
Suction performance of the vacuum cleaner is too low as the material being ground tends to block the filter.
  • Use a VC 20/40 performance filter or a dust filter bag.
The vacuum cleaner hose connector doesn’t fit the grinder.
Wrong hose connector.
  • Change the suction adapter.
The rate of working progress decreases.
The diamond cup wheel is blunt.
  • Sharpen the segments by making a few cuts in an abrasive material (Hilti sharpening plate or abrasive sand-lime block).
The grinder leaves undesired grinding marks on the material.
The cup wheel is too aggressive.
  • Use a less aggressive cup wheel.

DPC 20

Possible cause
Action to be taken
The LED doesn’t light.
The supply cord is not plugged in correctly.
  • Plug the supply cord into the power outlet.
The supply cable is defective.
  • Have the DPC 20 checked by Hilti Service.
No electric power at the DPC 20.
  • Check to ensure that the selector switch on the vacuum cleaner is set to AUTO when the DPC 20 is connected to the vacuum cleaner.
The LED blinks green.
The tool doesn’t achieve full power.
Supply voltage is too low.
  • Use a compatible electric supply.
The extension cord conductor cross section (gauge) is inadequate.
  • Use an extension cord with an adequate conductor cross section.
The LED blinks red.
The power tool has overheated or there are irregularities concerning the electric supply or temperature.
  • Switch the power tool off and allow it to cool down until the green LED lights again.
  • If the green LED doesn’t light, check the circuit breaker or fuse.

Unlisted fault

  • If the trouble you are experiencing is not listed in this table or you are unable to remedy the problem by yourself, contact Hilti Service.


Image alternative 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.
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  • Do not dispose of power tools, electronic equipment or batteries as household waste!

Manufacturer’s warranty

  • Please contact your local Hilti representative if you have questions about the warranty conditions.
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