Understanding the motor brushes

What are motor brushes?

The spindle motor brushes are small carbon blocks which serve to create an electrical contact between the rotor and stator (the inner and outer coils) of the spindle motor. 

The Yeti Tool SC0/1 spindle motors have two brushes, one on each side of the spindle motor. They can be found behind the rear cover of the spindle motor.

How do they work?

The brushes pass electrical current between the inner and outer coils of the spindle motor (it would be impossible to use a fixed cable due to the rotation of the inner core).

The brushes are held in a fixed position in the spindle motor housing, and make contact with the commutator (part of the rotating core of the spindle) as it spins. The brushes are spring loaded, so that they are pushed against and maintain contact with the commutator. 

This mechanism delivers a continuous supply of electrical current to the spinning core of the spindle, which is why it is so important that the brushes are maintained correctly. 

How long will they last?

Spindle motor brushes will inevitably wear out in time as they are in constant contact with the spinning commutator. The brushes are carbon, and so are softer than the copper commutator. This is intentional so that they will wear and the commutator won’t. 

Your SmartBench console will give you a reminder when it is time to check your brushes. This reminder is set to 120 hours of use as a default; however, this value will vary depending on factors such as spindle speed and load.

Can I replace the brushes myself?

Yes, replacing the spindle motor brushes is an easy job to do yourself, provided you keep a few pointers in mind. 

Click here to learn how to change your spindle motor brushes.