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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dennis Toth on August 25, 2011, 07:55:31 AM

Title: Motor "toothing - strong vs weak" what does it tell us
Post by: Dennis Toth on August 25, 2011, 07:55:31 AM

Guys,
Since rebuilding my AXI 2826/10 with new bearing I also bought a new Hacker 30XL10 just in case the rebuild went bad (it didn't). Comparing the two motors the AXI has very strong "toothing" feel where as the Hacker is softer toothing.

Question - does the stronger toothing indicate a stronger more "torquie" motor that has closer tolerance and would pull less amps for the same load?

Best,       DennisT

Title: Re: Motor "toothing - strong vs weak" what does it tell us
Post by: Igor Burger on August 25, 2011, 08:05:53 AM

No, "torque" (in mean torque on the shaft per A) is function of KV (strength of magnet to number of winging) ... toothing does not change it, also strenght of the magnets do not have too much with it, it is just difference in shape of "fingers" of the stator to shape of magnets and count of coils and magnes, gap smace etc ... simply design of magnet flux circuit

Title: Re: Motor "toothing - strong vs weak" what does it tell us
Post by: Dean Pappas on August 25, 2011, 09:54:14 AM

Hi Dennis,
The cogging you feel (that's the accepted term) is, as Igor said, a function of how the motor is designed.
The next question might be, which is better? There is no single answer, just different trade-offs.
Dean P.

Title: Re: Motor "toothing - strong vs weak" what does it tell us
Post by: Tim Wescott on August 25, 2011, 10:32:10 AM

Yup.  In a servo motor cogging is a royal pain in the behind (as is variations in torque in operation that aren't there when there's no current flowing).  But there's a whole bunch of factors that a motor designer has to fling around when doing a design, of which cogging torque is one of many.

For a prime mover it only matters if it starts shaking things apart.