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Hilti AG 125-20SE Angle Grinder User Manual
Quick guide for the Hilti AG 125-20SE angle grinder, covering assembly, operation, safety precautions, and troubleshooting.
Table of contents
Quick guide from the manual
This document provides essential information for the safe and efficient operation of the Hilti AG 125-20SE angle grinder. It is intended for professional users. Always ensure you have read and understood the full safety instructions provided in the original manual before use.
Device Description
The AG 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.
Assembly and Installation
- Side Handle: Screw the side handle into one of the provided threaded bushings.
- Guard: Align the triangular marks on the guard and the product, press the guard onto the spindle collar, and rotate until it engages.
- Front Cover: Push the front cover onto the standard guard until it clicks into place.
- Accessory Tools: Ensure the O-ring is present and undamaged in the clamping flange. Place the flange on the spindle, mount the accessory, and secure it with the clamping nut or optional Kwik lock nut.
Operation
- Speed Adjustment: Use the + and - buttons to select one of the 6 speed stages (3000 to 9400 rpm).
- Switching On: Plug in the device, press the rear part of the on/off switch, slide it forward, and lock it.
- Switching Off: Press the rear part of the on/off switch to release the lock and stop the motor.
Safety and Maintenance
- Safety: Always wear eye protection, hearing protection, and a hard hat. Use the auxiliary handle and hold the tool with both hands.
- Dust Filter: Clean the dust filter regularly. Replace it immediately if damaged.
- Maintenance: Keep air vents clear. Do not use water or steam cleaners. If the tool is used frequently on conductive materials (e.g., metal, carbon fiber), have it checked regularly by Hilti Service.
Troubleshooting
- Product does not start: Check power supply or have the cable/plug checked by a specialist.
- Product switches off (LEDs flash quickly): Overload. Release the switch, press again, and let the tool run at no load for 30 seconds.
- Product switches off (LEDs flash slowly): 3D ATC activated due to sudden movement. Switch off and on again.
- Product gets very hot: Electrical fault or clogged air vents. Switch off, let cool, and contact Hilti Service.
Manufacturer information
Hilti Corporation
Practical help
Common problems
Product does not start
Check power supply or have the cable/plug checked by a specialist.
Product switches off (LEDs flash quickly)
Overload. Release the switch, press again, and let the tool run at no load for 30 seconds.
Product switches off (LEDs flash slowly)
3D ATC activated due to sudden movement. Switch off and on again.
Product gets very hot
Electrical fault or clogged air vents. Switch off, let cool, and contact Hilti Service.
Before use
- Check that the O-ring in the clamping flange is present and undamaged.
- Ensure the correct guard is installed for the intended application.
- Verify that the accessory tool is securely tightened.
- Check that the side handle is firmly screwed in.
- Ensure the dust filter is clean.
Specs in practice
- Rated speed under no load
- 10,000 rpm
- Maximum permitted wheel diameter
- 150 mm (with appropriate guard)
- Ambient temperature for operation
- -17 °C to 60 °C
Model compatibility
- Use only synthetic-resin-bonded, fiber-reinforced wheels approved for at least 11,000 rpm and 80 m/s peripheral speed.
- For 150 mm accessory tools, a 150 mm guard (supplied separately) must be used.
- Dust hoods are required for mineral materials.
Manual page author
David Miller
Documentation analyst
Organizes user manual content into clear summaries, with attention to model details, product context, and everyday usability.