Re: What makes a motor a servo?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnc_4_me" <cnc4me@g...> wrote:
> Hi Scott,
>
> Believe it or not you are not comparing watts to watts. It is not
> real obvious here but knowing Mariss and being used to reading his
> posts watts is not watts in this instance. Well watt is it then (pun
> intended). Mariss often uses the unit watts as a measure of
> mechanical power because 746 watts = 1 hp.
>
> In his chart below he is not showing how much electrical power the
> motor draws at a RPM. He is in fact showing how much mechanical
> power each motor has at different RPM's. The point he was trying to
> make is that a stepper with 133 watts mechanical power has 320 IPM
> rapids when a servo with 266 watts mechanical power only has 145 IPM
> rapids.
>
> I agree with you that these motors and reduction ratios are poor
> choices for a milling machine. But he picked these motors and
> reduction ratios to make his point.
>
>
> BTW, a clue those numbers are not electrical power draw of the motors
> is the fact that a stepper draws full power at all speeds. That's
> why good stepper controllers have idle current reduction. So the
> stepper does not sit there and cook when it is not turning.
>
>
> Wally