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power tool brushless motor Answered

I want to replace the motor in my dremel for a brushless one and i just need some help in deciding which one to get. I also want to possibly upgrade the motor in my drill. The drill is only used for wood and i don't mind if either the drill or the dremel needs some kind of gearbox to get the most power from it. It would also be nice to know something about larger brushless motors as there doesn't seem to be much about them on the internet. Thanks in advance.



5 years ago

Hi, Lets start by comparing a common brush motor and induction motor.

Most brush motors are series DC ( also can run on AC ) good for hand drills,   hand grinders and hydraulic pumps.  
  • Series brush motors have a high speed at  No_Load (free_run) 
  • Now as the Load increases ( say you grab the drill chuck ) the speed drops but the twisting force ( Torque ) goes sky high and will rip the skin off of your bones.
  • These motors pull as much current as they need more torque to perform a rotary job.

Most induction motors are AC good for fans and centrifugal water pumps.
  • Induction motors will try to run at constant speed 
  • As the Load increases the speed drops and suddenly the motor stalls to a  zero speed growl .
  • These motors have no low speed torque  which is why a fan is a natural application.  At low RPM (Revolutions_Per__Minute) the fan blades are easy to turn.

Brush-Less motors are DC only electronic switched stators non_rotating field windings with a rotating armature magnet or squirrel_cage rotor.
  • This type of motor tries to use the Torque advantages of a series motor.
  • With the reliability and quiet operation of the induction motor.


this is some great information, thanks for your help. so am i correct in thinking that a brushless motor is better for most applications and if so, could you recommend any good motors for a dremel or drill.

I had no idea i would get a reply so quickly either, thanks.

Brushless motors are driven by an electronic frequency changing inverter.
The motor speed is determined by the frequency and as the frequency 
is lowered the voltage must be also be reduced.

Any inverter is much more expensive then a simple power tool.
These kind of motors and electronics come as a single unit designed
to be used for a specific application.

It is not something you can buy for retrofitting for a low cost brush motor.


oh, OK. that's a shame. thanks for all your help