How to Put a Grinding Disc on a Grinder

Grinders come in stationary bench and portable models.

Bench Grinder

These tools are convenient for sharpening lawn mower blades as well as a host of other metal grinding and shaping needs. Over time the grinding disc wears away requiring a replacement. Putting a grinding disc on a grinder requires removal of the old disc. Even though manufacturers have different types of locking nuts, the installation process is generally the same. Grinders that use special lock nuts have a wrench supplied with the grinder. If you do not have the special tool, purchase one from the manufacturer.

Turn off the power switch and unplug the bench grinder power cord. Lift the eye shields up if your grinder has them. Eye shields are clear plastic flip-down plates in front of the grinder wheel.

Remove the screws securing the disc cover to the side of the grinder with a Phillips-head screwdriver, if your grinder has covers. Pull the disc cover away from the grinder.

Insert a scrap piece of wood between the tool rest and the front of the grinding disc to prevent the disc from turning while removing. The tool rest is the raised metal plate where you place the item you are grinding during normal operation.

Loosen the nut securing the disc to the grinder with a socket wrench. If you are removing a right-side mounted disc, turn the nut counterclockwise. If removing a left-hand mounted disc, turn the nut clockwise. Remove the nut and the washer off the grinder shaft.

Slide the old grinding disc off the grinder shaft. Place a new grinding disc onto the shaft ensuring that the side closest to the grinder is flush against the inner spacer washer. Slide the outer washer over the shaft and against the outside face of the grinding disc.

Thread the securing washer over the shaft and tighten with the socket wrench. Place the piece of scrap wood between the disc and tool rest to prevent the disc from turning while tightening.

Portable Grinder

Unplug the grinder power cord from the wall outlet. Locate the spindle lock button on your grinder. The lock button is usually on top of the head or on the side. Press and hold the spindle lock button and turn the grinder over so the disc is facing you.

Remove the nut securing the disc to the grinder with a socket wrench. Some portable grinders use a special lock nut with holes and supply a special wrench. Remove the nut with the wrench supplied with the grinder.

Pull the washer off the grinder spindle and remove the old disc. Slide a new disc over the spindle and place the washer over the spindle and flush against the disc.

Thread the lock nut over the spindle and tighten with a socket wrench or the supplied wrench. Release the spindle lock.

Things You Will Need

  • Scrap piece of wood
  • Socket wrench
  • Replacement grinding disc


  • Use the appropriate size disc for your grinder. Refer to the owner's manual.


  • Do not use discs that are not rated for your units of revolutions per minute (RPM). The RPM rating is on the same tag as the serial and model number on your grinder.

About the Author

Kenneth Crawford is a freelance writer with more than 10 years of experience. His work has appeared in both print and online publications, including "The American Chronicle." Crawford holds an associate degree in business administration from Commonwealth College.