WFO 280 (01)

About these operating instructions

• Warning! Read and understand all accompanying documentation, including but not limited to instructions, safety warnings, illustrations, and specifications provided with this product. Familiarize yourself with all the instructions, safety warnings, illustrations, specifications, components, and functions of the product before use. Failure to do so may result in electric shock, fire, and/or serious injury. Save all warnings and instructions for future reference.
  
• products are designed for professional users and only trained, authorized personnel are permitted to operate, service and maintain the products. This personnel must be specifically informed about the possible hazards. 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.
  
• The accompanying documentation corresponds to the current state of the art at the time of printing. Please always check for the latest version on the product’s page on Hilti’s website. To do this, follow the link or scan the QR code in this documentation, marked with the symbol .
  
• Ensure that these operating instructions are with the product when it is given to other persons.
  

Explanation of symbols used

Warnings

Warnings alert persons to hazards that occur when handling or using the product. The following signal words are used:

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
	Dealing with recyclable materials
	Do not dispose of electric equipment and batteries as household waste

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 illustrations and refer to the numbers used in the product overview section
	This symbol is intended to draw special attention to certain points when handling the product.

Product-dependent symbols

Symbols on the product

The following symbols can be used on the product:

	Wear eye protection
	Wear ear protection
	Wear protective gloves
	Wear light respiratory protection
	Revolutions per minute
	Revolutions per minute
	Rated speed
	Diameter
	Protection class II (double-insulated)
	The product supports wireless data transmission compatible with iOS and Android platforms.

General power tool safety warnings

WARNING Read all safety warnings, instructions, illustrations and specifications provided with this power tool. Failure to follow all instructions listed below may result in electric shock, fire and/or serious injury.
Save all warnings and instructions for future reference.
The term "power tool" in the warnings refers to your mains-operated (corded) power tool or battery-operated (cordless) power tool.
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 a 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 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 extraction and collection facilities, ensure these are connected and properly used. Use of dust collection can reduce 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 injury 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 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 remove the battery pack, if detachable, 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 and accessories. 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.
  
• 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.
  

Belt sander and drum sander safety warnings

• Hold the power tool by insulated gripping surfaces, because the sanding surface may contact its own cord. Cutting a "live" wire may make exposed metal parts of the power tool "live" and could give the operator an electric shock.
  

Additional safety instructions

Personal safety

• Use the tool only when it is in perfect working order.
  
• 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.
  
• Do not touch moving parts – risk of injury!
  
• Wear suitable protective glasses, ear protection, protective gloves and light respiratory protection while using the power tool.
  
• Take breaks 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.
  
• 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.
  
• Before starting work, check the hazard class of the dust that will be produced when working. Use an industrial vacuum cleaner with an officially approved protection class in compliance with the locally applicable dust protection regulations.
  
• Use a dust removal system and suitable mobile dust extractor whenever possible. Dust from materials such as paint containing lead, some types of wood and also metal can 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 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.
  
• To avoid risk of injury, use only genuine Hilti accessories and accessory tools.
  
• Observe the national health and safety requirements.
  

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.
  
• Dirty or dusty power tools that have been used frequently for work on conductive materials should be checked at regular intervals by Hilti Service. Dust (especially dust from conductive materials) or dampness adhering to the surface of the tool may, under unfavorable conditions, lead to electric shock.
  

Power tool use and care

• Secure the workpiece. A workpiece clamped in a vice or secured by some other clamping devices is more secure than when held only by hand.
  
• Wait until the power tool stops completely before you lay it down.
  
• Switch the electric tool off and unplug the supply cord in the event of an interruption in the electric supply in order to avoid inadvertent restarting when the power returns.
  
• Grinding discs must be stored and handled carefully in accordance with the manufacturer’s instructions.
  
• Have the tool checked by Hilti Service after breakage of a disc, if the tool has been dropped or has fallen, or in the event of other mechanical damage.
  
• When working, always guide the supply cord and the extension cable to the rear and away from the power tool.
  
• Do not expose the product to rain or snow and do not use it in damp or wet conditions.
  

Product overview

1. Grip surface
   
2. Air vents
   
3. Thumbwheel for oscillation-rate preselection
   
4. On/off switch
   
5. Locking button
   
6. Slider
   
7. Dust bag
   
8. Clamp
   
9. Sanding plate
   
10. Clamp release lever
    
11. Securing screw for auxiliary grip
    
12. Auxiliary grip
    
13. Sanding sheet (Velcro-type attachment)
    
14. Flexible grinding disc
    
15. Suction adapter
    
16. Extraction hose
    
17. Screws for sanding plate
    

Intended use

The product described is a hand-held, electric orbital sander. It is suitable for dry-sanding the surfaces of materials such as wood, paints, varnishes, fillers, metal and plastic.

Operate the power tool only when it is connected to a power source providing a voltage and frequency in compliance with the information stated on the rating plate, and without use of water.

Auxiliary grip

This product has an auxiliary grip. This permits comfortable handling and optimum distribution of force, particularly for high rates of stock removal.

Dust removal system

This product has a built-in dust extractor with a dust bag. It also comes complete with an adapter for connecting a suitable external extraction system.
The dust extractor reduces the amount of dust in the air at the workplace and helps prevent dust accumulations.

Items supplied

Orbital sander, side handle, operating instructions.
Other system products approved for use with this product can be found at your local Hilti Store or online at: www.hilti.group

Technical data

	WFO 280
Weight in accordance with EPTA procedure 01	2.8 kg
Rated power input	350 W
Stroke rate under nominal load	3,000 min … 11,000 min
Sanding plate	223 x112 mm
Orbital travel	1.3 mm
Oscillation diameter	2.6 mm
Outside diameter, dust removal connector	30 mm
Ambient temperature for operation	−17 ℃ … 60 ℃
Storage temperature	−20 ℃ … 70 ℃

Noise information and vibration values in accordance with EN 62841

The sound pressure and vibration values given in these instructions were measured in accordance with a standardized test and can be used to compare one power tool with another. They can also be used for a preliminary assessment of exposure.
The data given represent 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 can vary. This can significantly increase exposure over the total working period.
An accurate estimation of exposure should also take into account the times when the tool is switched off, or when it is running but not actually being used for a job. This can 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

Sound power level (LWA)	89 dB(A)
Emission sound pressure level (LpA)	81 dB(A)
Sound level uncertainty (K)	3 dB(A)

Total vibration

Surface grinding with the standard side handle (ah,AG)	1.63 m/s²
Uncertainty, vibration values (K)	1.5 m/s²

Installing the auxiliary grip

• Use the hex key to secure the auxiliary grip to the housing.
  

Fitting the sanding sheet

There are various possibilities for fitting a sanding sheet.

Fitting a sanding sheet with Velcro-type attachment

1. Unplug the supply cord from the power outlet.
   
2. When pressing the sanding sheet on to the sanding plate, make sure that the openings in the sheet are in line with the holes in the sanding plate.
   
3. Press the sanding sheet on to the sanding plate.
   
4. Before starting work, check that the clamps are closed.
   

Fitting a clamped sanding sheet

1. Unplug the supply cord from the power outlet.
   
2. Operate the clamp release lever to open the clamp.
   
   • The front clamp is released, clearing the holder for the sanding sheet.
     
3. Slip the end of the sanding sheet into the clamp and flatten the sheet against the sanding plate.
   
4. When inserting the sanding sheet, make sure that the openings in the sheet are in line with the holes in the sanding plate.
   
5. Keeping the sanding sheet correctly positioned, close the clamp release lever to secure the sheet in position.
   
   • The clamp release lever must engage on both sides.
     
6. Check that the clamp always remains closed while work is in progress.
   

Setting the oscillation rate

• Set the thumbwheel for oscillation-rate preselection to a value between 1 (low) and 6 (high).
  
  • The electronics keep the oscillation rate constant even under load.
    

Installing the dust bag

1. Pull the plastic slider in the underside of the grip all the way out.
   
2. Slip the dust bag over the dust removal connector.
   
   • Make sure that the plastic slider engages the tab provided for the purpose on the dust bag.
     

Connecting an external extraction system

1. Fit the dust removal adapter.
   
2. Connect the extraction hose of a suitable external extraction system.
   

Safety

Switching on

Before plugging the supply cord into the power outlet, make sure that the product is switched off.

1. Plug the supply cord into the power outlet.
   
2. Press the on/off switch.
   
   • The motor runs.
     
3. Keep the on/off switch pressed and lock it in this position by pressing the locking button.
   
   • The motor runs continuously.
     

Sanding

1. With the motor running, position the orbital sander with the whole of its sanding face on the workpiece.
   
2. Applying moderate pressure, move the orbital sander steadily over the workpiece.
   

Switching off

• Release the on/off switch or, if the machine is in continuous-operation mode, press and then release the on/off switch.
  
  • The motor stops.
    

Changing a Velcro-attached sanding sheet

1. Switch the tool off.
   
2. Unplug the supply cord from the power outlet.
   
3. Peel the sanding sheet off the sanding plate.
   
4. Clean the sanding plate.
   
5. Insert a new sanding sheet .
   

Changing a clamped sanding sheet

1. Switch the product off.
   
2. Unplug the supply cord from the power outlet.
   
3. Release the clamp by lifting both rounded ends.
   
4. Remove the old sanding sheet.
   
5. Clean the sanding plate.
   
6. Insert a new sanding sheet .
   

Changing the clamp

1. Release the clamp by lifting both rounded ends.
   
2. Pull the clamp forward.
   
3. Lift the clamp.
   
4. Use thumb and index finger to squeeze the ends together.
   
5. Pull the clamp forward and out of the orbital sander's casing.
   
6. Replace the clamp.
   
7. Reinsert all the parts in the reverse of the disassembly procedure.
   

Changing the sanding plate

1. Using a suitable tool, remove the 8 combination Torx screws.
   
2. Remove the sanding plate.
   
3. Place the desired sanding plate in position.
   
4. Replace and tighten the screws.
   

Troubleshooting