How do I use an angle grinder safely?

Angle grinders remove material extremely fast and store a lot of energy in a spinning disc. Almost every serious incident comes from a wrong disc, a removed guard or a bind.

Safety

What you'll need

• Full face shield, plus goggles underneath
• Correct discs — cutting, grinding or diamond, rated above the tool speed
• Gloves, ear defenders and a suitable dust mask

Step by step

1. Match the disc to the material.Thin cutting discs for metal, diamond blades for masonry and tile, grinding discs for material removal, flap discs for finishing. Using a cutting disc for grinding is a common cause of shattering.
2. Check the disc speed rating.Printed on the disc in rpm. It must exceed the grinder's maximum speed. A disc rated below the tool can disintegrate the moment it spins up.
3. Never fit a wood carving or chain disc.They are sold, and they cause catastrophic injuries. An angle grinder has no chain brake and no anti-kickback protection.
4. Inspect the disc before every use.Chips, cracks or a disc that has been dropped. Ring-test a bonded disc by tapping it — a dull sound instead of a ring means discard it.
5. Keep the guard on and position it.Between you and the disc, so sparks and any fragments go away from your body and face. Removing the guard is the single most dangerous thing people do with this tool.
6. Wear a full face shield.Safety glasses are not enough. Grinders throw hot fragments at speed and face injuries are common.
7. Use both hands, always.Side handle fitted and used. One-handed grinding gives you no control when the disc catches.
8. Secure the workpiece.Clamped or in a vice. Holding metal by hand while cutting it is how the piece becomes a projectile and how hands end up near the disc.
9. Let it reach full speed before contact.And ease it into the work rather than dropping it on. Starting under load is a common cause of a disc breaking.
10. Cut with the lower quarter of the disc.So the disc's rotation pulls the tool into the work rather than pushing it back at you. Cutting with the top of the disc invites kickback.
11. Never let the disc bind.As a cut opens or closes, the disc can jam and the tool will jump violently. Support both sides of the cut so the kerf does not close on the disc.
12. Let the tool do the work.Light pressure. Forcing it overheats and stresses the disc, and a hot disc is a weak one.
13. Control the dust.Cutting masonry releases silica, which causes permanent lung damage. Use a water-suppressed or extracted cutter, or work outdoors with proper respiratory protection.
14. Check what you are cutting into.Old paint may contain lead, old boards may contain asbestos, and walls contain cables and pipes. Establish this before starting, not after.
15. Watch where the sparks go.They travel several metres and stay hot. Clear anything flammable, and be aware of them landing on glass, cars and plastic gutters.
16. Let it stop before putting it down.The disc coasts for a long time. Setting a running grinder down makes it move across the bench unpredictably.

Tips

• Check the disc's rpm rating exceeds the tool's. It is printed on the disc and it takes two seconds.
• Cut with the lower quarter of the disc so it pulls into the work rather than kicking back.
• A full face shield, not safety glasses. This tool throws hot fragments at speed.

Common mistakes

• Removing the guard for better access — The guard is what redirects a shattering disc away from your body. Grinder injuries without a guard are frequently severe and sometimes fatal.
• Using a cutting disc for grinding — Thin cutting discs have no lateral strength. Applying side pressure to one is a standard way to make it shatter at full speed.

If it doesn't work

Questions people ask