Re: [CAD_CAM_EDM_DRO] Re: stepper accuracy compared to servos...

ballendo wrote:

>Jon,
>
>Never any argument from me regarding HIGH-END("real") servo systems
>versus steppers...
>
>The post and thread was about low-end step-servos versus steppers...
>
>Ballendo
>
>P.S. I'd still like to see a ballbar test of the step-servos. That
>would pretty much put it to bed,either way, IMO. Say we take 3
>sherlines/taigs; one with Geckos, one with steppers, and one with
>your pico setup.
>

Yeah, I intend to do a "cook-off" of the Gecko 320 against the PWM
servo contraption that I'm working on, now. I have ways to get feedback
to EMC from both.

Oh, comparing accuracy of different motors on different machines will
muddy the waters for sure. I don't own a Sherline OR a Taig.

> Tune each up as much as possible, and then test 'em
>with the ballbar (does renishaw MAKE a ballbar that small?)
>

A ballbar is a total waste on a machine like the minimill. The errors
in the ways and screws would swamp the errors in the motors. I mean
I can actually SEE the table sway around the Z axis as it moves in the
X axis. I don't know if that's lumps in the gibs or a bend in the
leadscrew,
but it is pretty awful.

But, I will be able to compare the two systems using the EMC logging
and plotting functions.

> Maybe
>follow that up with some "common" toolpaths run on each machine,
>followed up by a CMM stat testing. Imention the sherline/taig because
>there's a pretty good likelihood of comparing apples to apples; not
>so with BP's or other candidates...
>
>

Jon