Re: [CAD_CAM_EDM_DRO] stepper - servo Holding tourque

Owen Lloyd wrote:

>Thank you Jon for the helpful info.
> I'd like to pose one further question, if you don't mind.
>I will be mounting my x axis directly to the ball screw via a coupler. My
>buddy took a look at my lay out and speculated that I'd need a larger [more
>torque] motor due to the absence of the pulleys.
>Is this so? I mean in theory it sounds right but I'm still not convinced and
>can't seem to grasp the math I need number crunch.
>
>

Well, with a direct drive, you get much higher speeds, and less torque.
With a 2:1 toothed belt
reduction, you double the torque but half the speed. Servo motors
usually have lots of speed,
so a belt reduction is a good move. Steppers are usually lacking on
high speed, so direct
drive may be a much better choice.

If you give me specifics, (motor specs, lead screw TPI) I can crank some
numbers for you.
Or, see my page on this at http://www.timgoldstein.com/CAD_CAM/motor.htm

Jon