Tools / Power Tools
Hilti 125-20SE Angle Grinder Instruction Manual
Quick guide for the Hilti 125-20SE angle grinder, covering setup, accessory installation, operation, safety warnings, and troubleshooting.
Table of contents
Quick guide from the manual
This document provides essential operating instructions for the Hilti 125-20SE angle grinder. It is intended for professional users. Always check the Hilti website for the latest version of the manual using the QR code provided in the document.
Device Description
The Hilti 125-20SE is a hand-held electric angle grinder designed for cutting, grinding, brushing, sanding, and hole cutting in metal and mineral materials without the use of water.
Safety
General Safety: Always wear eye protection. Use both hands to operate the tool. Do not use the standard guard for cutting work. Ensure the work area is clean and well-lit. Use personal protective equipment (dust mask, non-skid safety shoes, hard hat, hearing protection).
Kickback: Kickback is a sudden reaction to a pinched or snagged rotating wheel. Maintain a firm grip with both hands and position your body to resist kickback forces.
Operation
Switching On: Plug the cord into the outlet, press the rear section of the on/off switch, slide it forward, and lock it.
Switching Off: Press the rear section of the on/off switch; it will jump to the off position.
Speed Control: The tool features 6 speed stages (3000 to 9400 rpm), adjustable via + and - buttons.
Maintenance
Clean the air vents regularly with a dry brush. Keep the tool, especially the grips, dry, clean, and free from oil and grease. Clean the dust filter regularly and replace it if damaged.
Troubleshooting
If the tool does not start, check the power supply. If the speed control LEDs flash quickly, the tool is overloaded; release the switch and allow it to run under no load for 30 seconds. If they flash slowly, the 3D ATC system has been activated due to sudden movement; switch the tool off and on again.
Manufacturer information
Hilti Corporation
Practical help
Common problems
Product does not start
Check the power supply or have the cord/plug checked by a specialist.
LEDs flash quickly
Tool is overloaded. Release the switch, press again, and run under no load for 30 seconds.
LEDs flash slowly
3D ATC activated due to sudden movement. Switch off and on again.
Angle grinder gets very hot
Check for clogged air vents or electrical fault. Contact Hilti Service if necessary.
Before use
- Check that the O-ring is in the clamping flange and is undamaged.
- Ensure the correct guard is fitted for the intended application.
- Check that the accessory tool is secure.
- Ensure the side handle is properly installed.
- Verify the power supply voltage matches the rating plate.
Specs in practice
- Max wheel diameter
- 125 mm with standard guard; 150 mm with optional Hilti guard.
- Drive spindle thread
- M14.
Model compatibility
- Use only synthetic-resin-bonded, fiber-reinforced wheels approved for at least 11,000 rpm.
- Do not use cut-off wheels for grinding.
- Use specific dust hoods (DG-EX, DC-EX) for mineral materials.
Manual page author
Emily Carter
User documentation editor
Prepares concise manual descriptions and highlights the most useful setup, operation, and maintenance information for readers.