Safety and health newsletter for the Oregon construction industry


September 18, 2012

A properly guarded right-angle grinder

Tool talk: Portable abrasive grinders

One of the most common tools found in any shop, the portable grinder is incredibly useful for grinding and finishing material of all shapes and sizes.

What are the hazards?

The hazards associated with portable grinders are similar to those of pedestal or bench grinders. The rotating abrasive stone can cause severe abrasions and cuts. There’s also the potential for the abrasive stone to shatter and kickback from the spindle end. Other hazards such as flying fragments and sparks are present during grinding.

Safe practices

Portable grinders usually come with the manufacturer’s safety guard covering most of the wheel. Exposure to the wheel must not exceed a maximum angle of 180 degrees and the top half must be enclosed at all times. The guard must be mounted so it maintains proper alignment with the wheel.

Vertical “right angle” grinders must have a 180-degree guard between the operator and wheel. The guard must be adjusted so that pieces of a broken wheel will be deflected away from the operator.

Cup wheel grinders must be guarded as described above or with special “revolving cup guards,” which mount behind the wheel and turn with it.

All abrasive wheels must be inspected and “ring-tested” before mounting to ensure that they are free from cracks or other defects. The spindle speed of the machine also must be checked before mounting the wheel to ensure it does not exceed the maximum operating speed marked on the wheel. Always follow the manufacturer’s recommendations.

Requirements and standards for portable abrasive grinders

  • Oregon OSHA: Abrasive wheels and tools, 1926.303 [Division 3, Subdivision I]
  • ANSI/UL: 45-1990, Portable Electric Tools
  • ANSI: B7.1, Safety Code for the Use, Care, and Protection of Abrasive Wheels
  • ANSI: B11.9, Safety Requirements for Grinding Machines


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