Jig Saw: Grinding or Squealing Sound

When the bearings become worn, they can produce a squealing or grinding noise and may produce a vibration. A seized bearing can spin inside the housing causing this as well. To check the condition of the bearings, remove the base of the jigsaw then open up the case by removing the screws. Remove any hold down clamps, if your jigsaw has them. Remove the brushes. Lift up on the motor and pull the armature out. Spin the bearings to make sure they are not seized. Also check the housing, where the bearings are located, for signs of damaged produced by a seized bearing that is spinning against the housing. Make sure the bearing spins smoothly. If they are rough when spinning, they are worn.

On some models, you may have to remove the front assembly from the armature to access the front bearing. Some will pull part, while others will have to be taken apart. To replace a seized bearing, place the bearing in a bearing separator then place the face of the separator on top of a bench vice. Ensure the bench vice is open enough for the separator to only make contact. Using a punch, place it on the shaft and use a hammer to push the shaft free of the bearing. You also can use a puller to remove the bearing. Next, remove the separator and place the shaft in the bench vice with the soft jaws. Place the new bearing on the shaft and use a socket that makes contact with the inner race of the bearing only, to avoid damage. Then, use a hammer to install the bearing on the shaft. Reinstall the armature in the field and make sure the motor is back in place in the jigsaw case. Reinstall the brushes and finally, reassemble the case back together with the base.

When carbon brushes become badly worn, they can cause grinding or squealing sounds. Pieces of the carbon brush can also break off causing this. To inspect the carbon brushes for wear and damage, remove the base and open the jigsaw by removing the screws. Locate the brushes and remove them. Inspect them for damage such as cracks, chips, breakage or anything else out of the ordinary.

If you notice a break, inspect the inside for the broken piece as it may be caught somewhere, causing the grinding or squealing sound. Inspect the brushes for wear. Brushes 1/8 of an inch, or less, require replacement. If they are worn, replace them. Remove any hold down clamps. Pull up on the motor and remove the armature. Clean the commutator with 600-grit aluminum oxide sandpaper by rotating the armature in the direction of travel, only to provide a smooth, even surface. Use a plastic scribe to clean in between the bars on the commutator. Clean with electrical contact cleaner, wipe dry and reinstall back into the field. Ensure the motor is back in place and reassemble the case together. Finally, reattach the base.

Gears transmit power. When the teeth on the gears become worn, or broken, they will produce a grinding sound, since the teeth are not meshing together. To check the condition of the gears, remove the base and all of the screws securing the case together. Open the case and locate the gears. Spin the gears, looking for damaged teeth.

The next steps will vary according to models as they are all different. However, the procedure will be similar. Remove any hold down clamps. Pull the armature assembly out of the field. Remove the reciprocating shaft (yoke) from the assembly as well as the clip holding the gear on. Then, remove the gear. Install the new gear on the shaft with the clip.

Reinstall the reciprocating shaft. Some drive gears on the armature are part of the armature, therefore you will have to replace the armature. Reinstall the armature assembly back on the field and ensure the motor is placed down correctly in the case. Assemble the case back together with the base.