How to Replace the Armature on a Porter-Cable Router
The armature is the central part of your router's motor. The armature consists of copper windings, the commutator, the cooling fan, and the drive shaft. The field works with the armature to generate an electromagnetic field (which allows the armature to rotate). Carbon motor brushes press against the commutator and transfer electricity to the armature as it rotates.
Over time, the commutator can wear down (caused by its constant contact with the motor brushes). The armature can also be damaged by overloading the tool. (This can cause the armature to overheat, which often burns the insulation around the windings and creates a short-circuit). A damaged armature can also cause excessive sparking around the motor brushes, and smoke (or a burning smell) will be emitted from the motor. If damage occurs to the armature, it will need to be replaced.
Let's get started.
REMOVING THE ARMATURE
1. Remove the base.
a. Unplug the tool.
b. Loosen the clamp knob.
c. Thread the base assembly off the lower housing.
2. Remove the top cap.
a. Remove the (4) screws securing the top cap.
b. Remove the top cap.
3. Disengage the motor brushes.
a. Use long-nosed pliers to carefully lift and re-position the brush springs away from the backs of the motor brushes.
4. Separate the two halves of the motor housing.
a. Remove the two screws securing the upper bearing retainer.
b. Remove the armature “plug” from the center of the armature shaft using a hex driver and one of the wrenches supplied with your router (the wrench prevents the armature from rotating as the plug is removed).
c. Remove the four screws that secure the upper and lower housing.
d. Separate the two halves of the motor housing. (The armature should remain connected to the lower housing, and the field should remain in the upper housing.)
5. Remove the lower bearing retainer.
a. Remove the three screws securing the lower bearing retainer.
b. Remove the retainer.
6. Remove the collet spindle from the armature shaft.
a. Place an appropriately sized socket (along with a socket wrench) over the collet spindle.
b. Hold the armature securely (with your other hand) and strike the socket wrench with a rubber mallet until the collet spindle ‘breaks free’ from the armature shaft. (This may require several attempts.)
c. Unthread and remove the collet spindle from the armature shaft.
7. Remove the armature.
a. Use a rubber mallet to tap the armature out of the bearing.
b. Remove the armature assembly from the motor housing.
INSTALLING THE NEW ARMATURE
8. Install the armature.
a. Install the new armature into the motor housing.
b. Align the shaft of the armature with the bearing.
c. Use a rubber mallet to tap the armature into the bearing.
REASSEMBLING THE UNIT
9. Reinstall the collet spindle.
a. Thread the collet spindle onto the shaft of the new armature.
b. Secure the collet spindle with the socket wrench (and the rubber mallet).
10. Reinstall the lower bearing retainer.
a. Install the lower bearing retainer.
b. Secure the bearing retainer with the (3) screws.
11. Connect the upper and lower motor housings.
a. Slide the field assembly (and the upper housing) over the armature (and the lower housing).
b. Secure the two halves of the motor housing with the four screws.
12. Reinstall the upper bearing and retainer.
a. Install the upper bearing retainer plate (containing the bearing) over the armature shaft.
b. Secure the bearing retainer to the motor housing with the two screws.
c. Install and tighten the plug using a hex driver and the wrenches supplied with your router.
d. Put the upper bearing back onto the armature shaft and secure the bearing holder.
e. Secure the armature shaft to the bearing with the set screw and secure the spindle shaft with the wrench.
13. Reinstall the motor brushes.
a. Install the motor brushes into the brush holders (if not already installed).
b. Use long-nosed pliers to reposition the brush springs (back onto the motor brushes).
c. Position the insulator flaps over brush wires.
14. Reinstall the speed control lever.
a. Install the speed control lever onto the motor housing (the notch on the lever fits over the tab on the speed control module).
15. Reinstall the top cap.
a. Install the top cap.
b. Secure the top cap with the (4) screws.
16. Reinstall the base.
a. Thread the base assembly onto the motor housing.
b. Tighten the clamp knob to secure the base assembly.