Same holding torque but different number of leads...
 

hi,

Suppose we have 2 motors with the same specs, but one has 6 wires and the other has 8.

Would there be a difference in torque between the two motors when running them half-coil? Will both of them theorically have exacltly 1.4x less holding torque than if they were to be wired "full coils"?

thanks,
francis

Theoretically speaking, yes, as long as the construction of the coils are the same.
Again, 1.4X is only an approximate/general number, there are many other factors involve too, i.e. the corner frequency, the coil internal resistance... etc etc... Just to confuse you further :p

thanks ken,

I have another question,

I have only a 56VDC power supply. Can I alter the amperage feed to the motor instead of the voltage to find a "perfect balance" between performance and overheating?

Richards posted earlier on this thread that he runs his PK299-F4.5a at 35VDC and 6.3 amps, bipolar paralell, and the motor runs much smoother than at 60VDC, as he first tested.
Could I run the same motor at 60VDC, for example, and lower the amperage instead of the voltage, and get a better balance, just like Richard got, using 35VDC?

Thanks again,
F

Francis-

Mike (Richards) and others are actively discussing that sort of question starting around post #40 here.

Francis,
I'll leave a post in the other thread that Brad highlighted to respond to your question.

Francis, a very common misconception is that the published holding torque of a motor is the important criteria for a router.

The important torque is the one at higher speeds, when the machine is cutting.

Fransic, like all other electrical machine, you cannot just alter the current of the motor, electric motors draw current when they need it even if it means self-destruction & the only thing we can do is to LIMIT the max supply current, just like restricting the fuel line of an engine. AND it is almost impossible to have a "perfect balance" all the time, due to the vast variate operating condition of stepper motors in an CNC machine (speed change, accelerare, decelerate....etc etc). You can only work within a safe operating "ZONE" at best.

To confuse you even further, the other factor which contributes to load current are voltage, frequency, coil inductance, coil internal resistance, coil capacitance, magnetic flux of the magnet & external loads such as friction... etc etc etc... not all necessary to know to operate a motor properly...

Thank all,

It's really worth it having a look here (same link bradm showed me) on the posts about motors electrical characteristics and playing with what you have to keep the heat down and have enough power available...
f.