Cordless Grinder Safety and Pack Choice

A cordless angle grinder cuts, grinds and sands with a disc spinning at very high speed. It's one of the most useful tools in the shed and one of the most dangerous. Here's how to use one safely and which battery suits it.

1. Before you start

Guard on: keep the guard fitted and set between you and the disc.
Right disc: use a cutting disc for cutting and a grinding disc for grinding. Never grind with the face of a thin cutting disc.
Check the rating: the disc's maximum speed must be at least the grinder's speed, and the disc must match the grinder's size.
Check the disc: don't use a chipped, cracked or dropped disc.
Side handle: fit it and use two hands.

2. Protect yourself

Safety glasses and a face shield, hearing protection and gloves.
No loose sleeves, and tie back long hair.
Clear anything that can burn out of the spark path, and keep a fire extinguisher handy.

3. Using it

Clamp the work. Don't hold small pieces in your hand.
Let the disc reach full speed before it touches the work.
Stand to the side of the disc's line, never in line with it.
Don't force it. Let the disc do the work.
Wait for the disc to stop before you put the grinder down.
Remove the battery before changing discs.

4. Kickback

If the disc catches or pinches, the grinder can jerk back hard towards you. Many cordless grinders have a kickback brake or a paddle switch that stops the motor when you let go. These are worth looking for.

5. Which battery?

Grinders pull hard, especially when cutting steel or grinding welds.
A 4 to 5Ah pack suits most work. Use 6Ah or larger for long cuts and heavy grinding.
Small 2Ah packs heat up quickly and cut out under load.
Let a hot pack cool before you charge it.

Check a tired pack before you blame the grinder. See Why Won't My Cordless Battery Charge?