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Q & A: Help! My router makes huge sparks!


Q & A: Help! My Router Makes Sparks!


When I run my router I see lots of small, blue sparks inside. Recently the sparks have grown larger. Is this OK?



Nope. Small sparks are normal, but large sparks are an indication that your brushes are wearing short. That means your router is running inefficiently. It’s time to remove the brushes and possibly replace them.

The sparks are the electrical arcing of current from the brushes to the motor’s commutator (the large cylinder inside the housing). Large sparks mean the brushes are too short to be adequately held tight to the commutator by their springs. As a result, the motor has to work harder to make the electricity jump the gap between the brushes and commutator.

Every router has two brushes.To service them,unplug the router, remove the caps and pull out the brushes. If they are chipped, cracked or shorter than 1/4 in., replace them with ones made specifically for your router.To remove any carbon dust, use an air compressor or a can of compressed air to blow out the holes that house the brushes.Look into the holes with a flashlight. If the commutator is pitted or severely worn, it will need professional servicing. If the brushes are in good shape put them back in the same holes, in the same orientation and replace the caps. If you have installed new brushes, run your router for two to three minutes to fully seat them.Your router may “cough” and sputter a bit until it comes up to full speed, but that’s normal.

This story originally appeared in American Woodworker February 2001, issue #85.

February 2001, issue #85

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