Die Grinders

A die grinder is a small rotary tool that spins burrs, mounted stones, sanding discs and small cut-off wheels at 20,000 RPM or more. That speed makes it useful for grinding welds, porting and deburring, and it makes a broken wheel or a grabbing burr very dangerous.

• Welders & fabricators
• Mechanics
• Maintenance

Biggest hazards

• Burst wheels and stones: an accessory spun faster than its rating can shatter.
• Grab and kickback: a burr can catch an edge and yank the tool or whip it back at your hand.
• Entanglement: loose gloves, sleeves, rags or hair can wrap on the spinning shank.
• Flying chips, sparks and hot metal.
• Noise, vibration and metal dust, including hazardous metals like stainless and galvanized steel.

Accessories

• Check the RPM rating: every burr, mounted point and wheel has a maximum speed. It must be at least as high as the tool’s rated speed.
• Collet depth: insert the shank as far as the maker requires, usually most of the shank. A long overhang lets the accessory wobble and break.
• Right collet size for the shank (¼ inch, ⅛ inch or 6 mm). Never shim a loose fit.
• Cut-off wheels need a guard. Use only wheels rated for the tool.
• Inspect burrs for dull or chipped flutes and stones for cracks before use. Throw out dropped stones.

Using it

• Disconnect air or power before changing accessories.
• Run a new accessory at full speed for a moment, pointed away from people, before touching the work.
• Hold the tool with both hands when you can, and let the accessory do the cutting; don’t force it.
• Move burrs in the direction that pulls the tool away from edges, and avoid jamming them into corners.
• Clamp the workpiece. Don’t hold small parts in your hand.
• Let the tool stop before setting it down.

Air tools

• Pneumatic tools must be secured to the hose so they can’t disconnect accidentally.
• Use whip checks on hose connections, and keep hoses out of walkways.
• Never point compressed air at anyone or use it to clean your clothes.

See Air Compressors.

PPE checklist

• Safety glasses plus a face shield
• Hearing protection
• Snug-fitting gloves that won’t catch (or no gloves near the spinning shank, if your site’s assessment says so)
• FR or cotton clothing when grinding throws sparks; no loose sleeves
• Respirator if grinding coated, galvanized, stainless or lead-painted metal without enough ventilation

Last updated: October 2, 2026