15 · Power Tools

Angle Grinder

Also called Grinder · Disc grinder · Side grinder

A handheld spinning-disc tool for grinding, cutting, polishing and sanding metal, concrete, stone and tile.

Electric (corded)

Overview

An angle grinder spins a disc at high speed at right angles to the body. The disc fitted is what decides the job — cutting, grinding, polishing or sanding — across metal, concrete, stone and tile.

We rent a 4.5 in, light enough to use one-handed, and a 7 in whose larger disc reaches further into a cut.

Cutting rebar, bolts and metal pipe, grinding welds and removing rust, cutting tile and stone with a diamond disc, and removing mortar and paint.

Check the disc's maximum RPM is higher than the grinder's speed before fitting it. A disc spun faster than its rating can burst, and that is the accident this tool is known for. Keep the guard fitted and positioned between the operator and the disc.

Best uses

  • Cutting rebar, bolts and metal pipe
  • Grinding welds and removing rust
  • Cutting tile and stone (diamond disc)
  • Removing mortar and paint

Troubleshooting

Disc wobbles

Checks to try, in order

  1. Unplug, remove the disc and re-seat it with the flange the right way round.
  2. Throw away any cracked or chipped disc.

Reference draft — always follow the manufacturer’s manual.

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Cuts slowly or the disc glazes

Checks to try, in order

  1. Use a disc suited to the material.
  2. Replace a worn disc.
  3. Let the tool's speed do the work — don't press hard.

Reference draft — always follow the manufacturer’s manual.

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Tool won't switch onShared · Electric (corded)

Likely causes

  • Tripped GFCI or breaker
  • Lock-off button
  • Damaged cord
  • Dead outlet

Checks to try, in order

  1. Check the outlet works and reset any GFCI / RCD that has tripped.
  2. Release the lock-off button or safety switch before squeezing the trigger.
  3. Inspect the cord and extension lead for cuts, crushed sections or damaged plugs.
  4. If running from a generator, make sure it's running and its breaker hasn't tripped.

A damaged cord or plug means the tool is out of service. Tag it and return it — never tape a cord.

Reference draft — always follow the manufacturer’s manual.

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Keeps tripping the breakerShared · Electric (corded)

Likely causes

  • Circuit overloaded
  • Undersized extension cord
  • Blunt accessory

Checks to try, in order

  1. Plug into a circuit with nothing else heavy running on it.
  2. Use a shorter, heavier extension cord. Long, thin cords starve the motor and trip breakers.
  3. Don't force the tool — a dull bit, blade or disc makes the motor draw more current.

Reference draft — always follow the manufacturer’s manual.

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Overheating, burning smell or heavy sparkingShared · Electric (corded)

Checks to try, in order

  1. Stop and unplug the tool.
  2. Check the motor vents aren't blocked with dust.
  3. Let it cool, fit a sharp accessory and let the tool's weight do the work.

Heavy sparking from the vents or a burning smell that returns points to worn brushes or a failing motor — workshop only.

Reference draft — always follow the manufacturer’s manual.

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Safety

  • Use two hands, the side handle and a face shield. Kickback is sudden.
  • Never grind with a thin cutting disc — side loads can shatter it.
  • Never press the spindle lock while the disc is spinning.

For electric (corded)

  • Inspect the cord and plug before every use. Use a GFCI/RCD outdoors or near water.
  • Unplug before changing blades, bits, discs or pads.
  • Wear eye protection, and a dust mask when cutting, grinding or sanding masonry.

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