Re: [CAD_CAM_EDM_DRO] How do you get 6/10 of a step?

Hi John,

Basically the answer is that you don't. The only thing that you can do is
reduce the error by gearing down the stepper to lead drive. Drive the
lead-screw with a 4 or 5 time reduction. This will increase the torque
available but reduce the speed. The only other way is to fit driver
electronics that will micro-step.

Regards,

Terry

> Ok, here is my dumb question for those that know how all this stuff
> works.
>
> If you have a stepper motor running is 1/2 step mode so that there are
> 400 steps per revolution attached to a 20 tpi lead screw you get 8000
> steps per inch. Now supposing I want to move that axis exactly 1.0197
> inches, that would appear to me to take 8157.6 steps. The question is
> how do you get the 6/10 of a step? I know, that is only .000075 of an
> inch, maybe I am being paranoid about precision but it seems to me
> that all this can accumulate to quite a bit over many moves along the
> same axis. Is it the common practice to round up or down when
> calculating the number of steps to move?
>
> Thanks
>
> John Guenther