Tools / Power Tools
Bosch GEX 12V-125 Professional Cordless Random Orbit Sander User Manual
Quick guide for the Bosch GEX 12V-125 Professional Cordless Random Orbit Sander. Includes assembly, battery charging, sanding sheet replacement, dust extraction, and operation instructions.
Table of contents
Quick guide from the manual
The Bosch GEX 12V-125 Professional is a cordless random orbit sander designed for dry sanding of wood, plastic, filler, and coated surfaces. Always remove the battery before performing any maintenance, changing accessories, or transporting the tool to prevent accidental activation.
Assembly and Setup
Battery Charging: Use only the chargers listed in the technical data. The battery is supplied partially charged; charge it fully before the first use. The battery is protected against deep discharge by Electronic Cell Protection (ECP).
Removing the Battery: Press the release buttons and pull the battery out of the tool. Do not use force.
Changing the Sanding Sheet: Lift the sanding sheet from the side and pull it off the sanding pad. Clean the pad of dust and dirt before attaching a new sheet. Ensure the holes in the sanding sheet align with the holes in the sanding pad for optimal dust extraction.
Operation
Switching On/Off: Press the on/off switch to start the tool. Press it again to switch it off. Ensure you can operate the switch without releasing the handle.
Preselecting Orbital Stroke Rate: Use the thumbwheel to select the required orbital stroke rate, even during operation. The rate depends on the material and working conditions and can be determined by practical tests.
Dust Extraction
Self-generated extraction: Attach the complete dust bag to the extraction outlet until it is flush with the tool. Empty the dust bag in good time to ensure optimal extraction. When working on vertical surfaces, hold the tool so the dust bag faces downward.
External extraction: Connect a dust extraction hose to the extraction outlet and connect it to a suitable vacuum cleaner.
Maintenance and Cleaning
Always keep the tool and ventilation slots clean for safe and efficient operation. For repairs or spare parts, contact an authorized Bosch service center.
Manufacturer information
Bosch
Practical help
Common problems
Tool stops automatically
The battery is discharged or the overload protection has been triggered. Do not continue to press the on/off switch.
Dust extraction is poor
Empty the dust bag in good time. Ensure the holes in the sanding sheet align with the holes in the sanding pad.
Battery LEDs flash quickly
The battery temperature is outside the operating range (-30 to +70 °C) or the overload protection has been triggered.
Before use
- Ensure the battery is fully charged.
- Check that the sanding sheet is correctly attached and aligned.
- Ensure the dust bag or extraction hose is properly connected.
- Verify the tool is switched off before inserting the battery.
- Wear appropriate personal protective equipment (safety glasses, dust mask).
Specs in practice
- No-load speed
- 6000–10000 min-1, adjustable via thumbwheel.
- Orbit diameter
- 2.5 mm, determines the sanding pattern.
- Sanding disc diameter
- 125 mm, standard size for this model.
Model compatibility
- Use only original Bosch sanding accessories.
- Recommended batteries: GBA 12V...
- Recommended chargers: GAL 12..., GAX 18...
Manual page author
David Miller
Documentation analyst
Organizes user manual content into clear summaries, with attention to model details, product context, and everyday usability.