How to Replace the Carbon Brushes on a DeWALT Grinder

Your grinder's motor uses two carbon brushes to conduct electricity to the armature. The brushes do this through the armature's commutator. The carbon brush will wear down over time (from rubbing against the rotating commutator) and will need to be replaced. Worn brushes can cause excessive sparks around the commutator. The sparks can also be caused by a damaged armature, so you'll want to carefully inspect both components if sparks are present.

Let's get started.

REMOVING THE CARBON BRUSHES   1. Remove the brush door.

a. Remove the screw securing the brush door to the motor housing.

b. Remove the brush door from the motor housing.

  2. Remove the carbon brush.

a. Use a small pick to lift the brush spring away from the brush arm.

b. Reposition the spring onto the post on the motor housing. (This will keep the spring out of the way.)

c. Use long-nosed pliers to disconnect the brush lead wire from the connector.

d. Pivot the brush arm away from the armature.

e. Remove the carbon brush from the brush arm.

INSTALLING THE NEW CARBON BRUSHES

  3. Install the carbon brush.

a. The new carbon brush is beveled to ensure smooth contact with the armature. Verify that the bevel is correctly oriented (facing the armature) as you install the new brush.

b. Thread the lead wire of the new carbon brush through the opening on the underside of the brush arm.

c. Pull the brush wire (from the top of the brush arm) to seat the new carbon brush into the arm.

d. Pivot the brush arm (and brush) toward the armature.

e. Connect the brush lead wire to the terminal on the motor housing.

f. Reposition the brush spring onto the back of the brush arm.

REASSEMBLING THE UNIT

  4. Reinstall the brush door.

a. Install the brush door onto the motor housing.

b. Secure the brush door with the screw.

  5. Repeat.

a. Repeat these steps to replace the second carbon brush (if necessary).