Brushless Motors in Cordless Tools

As woodworkers and DIY home-improvers, we live in an old-tech world that occasionally benefits from high-tech improvements. One of the most important and interesting developments is the introduction of brushless motors into portable power tools. Companies such as Festool, Hitachi, Makita and Milwaukee have recently rolled out, or are close to releasing, cordless power tools with brushless motors.

Hitchi's 14.4V 3.0Ah Lithium Ion Brushless Impact Driver (WH14DBL)	Makita's 18V LXT Lithium-Ion Cordless 3-Speed Brushless Motor Impact Driver Kit (LXDT01).

I‘m not qualified to explain the technical details of how each of these types of motors work, but in a nutshell: In a typical motor, there are permanent magnets mounted on the outside and a spinning armature or rotor contains an electromagnet on the inside. The poles of the electromagnet are repeatedly changed to keep the rotor spinning.  A mechanism called a commutator rubs against the metal parts called the brushes to change the polarity flow.

In a brushless motor, the arrangement is reversed; the permanent magnets are inside (on the rotor) and the electromagnets are moved to the outside. A computer replaces the commutator and brushes as the means of charging and changing the poles of the electromagnets.

 The advantages of brushless motors include the potential for reduced tool size and weight, significantly more power and greater durability (Check out the extreme tests this guy puts his Festool drill through in the video below. Note: We had nothing to do with this test and do not know the source). On the downside, it costs more to buy a tool that uses this technology, and there are few products available at this time.