How to Replace Carbon Motor Brushes on a Porter Cable Sander

Motor brushes worn out? It's time to face the fix. Whether you are a master carpenter or a seasonal sander, eReplacementParts.com provides the parts, procedures and facts you need to fearlessly fix what fails you.

Your Porter Cable Quicksand sander has two motor brushes. They are responsible for transferring power to the motor's spinning armature. The brushes, which are made of carbon, will eventually begin to wear down. When this happens, the motor no longer receives the electricity it needs to function smoothly.

Symptoms of worn brushes include erratic or intermittent operation, decreased power, or a complete inability to activate the sander.

This article provides step-by-step instructions for removing and installing carbon motor brushes on a Porter Cable Quicksand 333 series sander.

Let's get started.

REMOVING THE MOTOR BRUSHES [top] 1. Remove the sanding pad.

Remove the (3) screws from the sander pad.

Remove the sanding pad from the sander.

  2. Remove the clutch belt.

Remove the clutch belt from the fixed pulley and the pad support pulley.

  3. Remove the pad housing.

Remove the (2) screws from the pad housing.

Separate the two halves of the pad housing.

Separate the sander from the pad housing.

  4. Remove the housing O-ring.

Use a screwdriver to pry the O-ring out of the groove in the housing.

Work around the edges of the O-ring; stretching it around the pad support assembly as you move.

Remove the O-ring from the sander.

  5. Remove the pad support.

Grasp the fan to prevent the pad support from rotating.

Remove the (1) screw from the pad support.

Remove the pad support (and washer) from the sander.

  6. Remove the fan.

Slide the fan assembly off the spindle and away from the sander.

  7. Split the motor housing.

Remove the (4) screws from the motor housing.

Remove the top half of the motor housing.

  8. Remove the motor brush(es).

Pull the brush holders (containing the motor brushes) away from the armature. (There are two motor brushes on this unit.)

Disconnect the wire lead from the motor brush.

Slide the motor brush out of the brush holder.

Repeat this step to remove the second motor brush.

  INSTALLING THE NEW MOTOR BRUSHES [top] 9. Install the motor brush(es).

Install the new motor brush into the brush holder.

Pull the motor brush connector tab through the opening in the brush holder.

Connect the wire lead to the new motor brush.

Press the carbon brush against the armature; compress the spring.

Seat the brush holder in the slot on the motor housing.

Repeat this step to install the second motor brush.

  REASSEMBLING THE UNIT [top] 10. Reinstall the top half of the motor housing.

Install the rubber bumper into the recess on the motor housing.

Visually inspect the wires for potential pinch-points; adjust the wires as necessary.

Install the top half of the motor housing.

Secure the motor housing with the (4) screws.

  11. Reinstall the fan.

Slide the fan onto the spindle.

  12. Reinstall the pad support.

Install the pad support onto the sander.

Install the washer onto the pad support. (The side with the recess should be facing away from the bearing).

Secure the pad support with the (1) screw.

  13. Reinstall the housing O-ring.

Install the housing O-ring into the groove on the motor housing.

  14. Reinstall the pad housing.

Install one half of the pad housing onto the sander (the seam should align with the seam on the motor housing).

Install the second half of the pad housing onto the sander.

Secure the pad housing with the (2) screws.

  15. Reinstall the clutch belt.

Install the clutch belt onto the fixed (small) pulley.

Stretch the clutch belt onto one side of the pad support.

Rotate the pad support to seat the clutch belt.

  16. Reinstall the sanding pad.

For easy alignment: Pass a small screwdriver through one of the screw holes on the sander pad; then insert the end of the screwdriver into one of the holes on the pad support.

Install the sanding pad.

Secure the sander pad with the (3) screws.

Sanding can be a demanding task. But you don't have to rough-up your accountant to smooth-out your countertops. As you just learned, repairing your own power tools is simple when you follow our step-by-step guides. Not only did you expand sander functionality at a fraction of the cost of replacement; you have taken the edge off all future repairs.

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