Re: [CAD_CAM_EDM_DRO] what the world needs now ... backlash aware stepper motor driver

Doug Fortune wrote:

> While pondering how to cnc convert my bench
> mill (bigger than an RF-45 but smaller than a
> GEM500) which has 1" dia * 10 TPI acme leadscrews
> with 10 thou backlash in the X axis and 8.5 thou
> in the Y axis....
>
> I thought it might be an idea for someone to
> build backlash aware stepper motor drivers.
>
> Such a beast would have dip switches to indicate
> at setup time what the backlash was (in steps), and
> upon detecting any reversal of direction, quickly
> counts up through that selected number of steps
> to take up the backlash.

The problem with this is that in most cases, the driver does
not know what top speed and acceleration are acceptable
to the stepper motor without losing steps. The CNC control
knows this info, however. So, it means that top speed and
acceleration have to be built into the stepper driver as well,
with lots more dip switch positions.

Jon