Re: [CAD_CAM_EDM_DRO] positional resolution

> A leadscrew with 20tpi and 200step/rev should have a positional
> resolution of 1/(20x200) = 0.00025 in.
>
> Have I missed something in the above calculation because I read on
> the website of a system vendor listing the positional resolution as
> 0.000125 in.

Yes, you can relatively easily run the motor in half step mode
(one winding on, both windings on, other winding on, etc)

> Further, if in the above example, one uses 10x microstepping, is it
> presumptous to claim a positional resolution of 0.000025in?

No. It's just presumptious to claim an accuracy of that, and may even
be presumptious to claim that kind of precision. But you will have
very smooth micro feeds.

One problem with small step increments is that you have to generate
pulses very quickly. Some PC based programs need a fast processor to
do this, or compromise by generating uneven steps which can lead to
missing steps, stalling, etc.

In other words, one doesn't want the resolution too high or too low,
but just right.

Chris