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Angle Grinders: Choosing 4½" or 9", the Right Disc for the Job, and Using One Safely
Quick answer: For general workshop and site use, a 4½" (115 mm) grinder is light and handles most cutting and grinding; a 9" (230 mm) grinder cuts deeper and faster on thick steel and masonry but is heavier. Fit the right disc (thin cutting disc to cut, thicker grinding disc to grind, flap disc to finish, diamond blade for masonry), never exceed the disc's rated speed, and always keep the guard on. H-TECH Bosch grinders from KSh 6,990.
Key facts
- 4½" for most jobs
- 9" for heavy cutting
- Right disc, rated speed
- Guard on, PPE always
On this page
Bosch Power Tools at H-TECH
Bosch – GWS 700 Professional Angle Grinder.KSh 6,990
Bosch GWS 2200-230 Angle Grinder Professional (9 Inches)KSh 15,800
Bosch GKS 140 Circular Saw 7-1/4"KSh 15,830
BT CHOP/MULTICUTSAW GCO 240 PROFESSIONALKSh 28,500
Bosch Orbital Sander GSS 2300KSh 12,700| Product | Price |
|---|---|
| Bosch – GWS 700 Professional Angle Grinder. | KSh 6,990 |
| Bosch GWS 2200-230 Angle Grinder Professional (9 Inches) | KSh 15,800 |
| Bosch GKS 140 Circular Saw 7-1/4" | KSh 15,830 |
| BT CHOP/MULTICUTSAW GCO 240 PROFESSIONAL | KSh 28,500 |
| Bosch Orbital Sander GSS 2300 | KSh 12,700 |
Current listed prices incl. VAT (updated 19 October 2026).
4½" vs 9" Angle Grinder
| 4½" (115 mm) | 9" (230 mm) | |
|---|---|---|
| Weight | Light, one-hand control with side handle | Heavy, two hands always |
| Cutting depth | Shallow | Deep |
| Best for | Fabrication, finishing, small cuts | Thick steel, kerbs, blocks, pipes |
| Typical user | Welders, fabricators, plumbers, DIY | Construction sites, heavy workshops |
Which Disc for Which Job?
| Disc | Use |
|---|---|
| Thin cutting disc (inox for stainless) | Cutting sheets, tubes and rods |
| Grinding disc (thicker) | Removing welds and burrs |
| Flap disc | Smoothing and finishing welds |
| Wire brush / cup | Rust and paint removal |
| Diamond blade | Tiles, blocks, concrete |
For stainless steel, use discs marked for stainless (inox) and keep them separate from discs used on mild steel, which can leave particles that rust. More on stainless work: stainless fabrication business.
Safety Rules
- Wear eye and face protection, hearing protection and gloves; no loose clothing.
- Keep the guard on and positioned between you and the disc.
- Check the disc is the right size and rated for at least the grinder's speed; never use a damaged disc.
- Use the side handle and both hands; let the disc reach full speed before cutting.
- Clamp the work; never cut with the disc's face.
- Keep sparks away from fuel, gas and people.
- Unplug before changing discs.
Care and Maintenance
- Blow dust out of the vents regularly.
- Replace carbon brushes when sparking increases (how to replace carbon brushes).
- Check the cable and plug before use.
Watch: Fabrication and components
Frequently asked questions
Which angle grinder size is best?
A 4½" (115 mm) grinder covers most jobs; a 9" (230 mm) suits heavy cutting.
Can I cut stainless steel with an angle grinder?
Yes, with a thin cutting disc rated for stainless (inox).
What disc do I need to cut concrete?
A diamond blade made for masonry.
Why does my grinder spark a lot inside?
Worn carbon brushes or a motor fault; check the brushes.
Is it safe to remove the grinder guard?
No. Always keep the guard fitted.