Re: [CAD_CAM_EDM_DRO] Re: Why is the push to such high step rates (Grex and Arc100)?

turbulatordude wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
><mariss92705@...> wrote:
>
>
>>256 microstep drive at 3,000 RPM equals a 2.56 MHz step pulse
>>frequency.
>>
>>
>>
>
>256 microsteps ?
>
>I had thought that at 10x the microsteps were not really dead-on balls
>accurate (an indusry term) so just how useful is a 256 microstep when
>it comes to motion control of our mills and routers ?
>
>
>

It isn't. I believe Mariss is absolutely correct that any finer
division of the motor's
inherent steps below about 10 is pointless, unless the motor has an encoder.

There definitely are closed-loop microstepping systems, where they need fine
microstep resolution to keep the system from dithering under mechanical
load.

Without an encoder, there is no way to control motor position even to a
single
full step. Friction and torque applied to the motor will cause the
position to
be offset from the nominal step position. And yet, they keep making these
systems.

Jon