Re: stepper vs. servo - Allegro and ignoring the edges....

That is the point I disagree with. Though a motor may have a +/-3%
non-accumulative tolerance, it does not mean the steps adjacent to
the current one will vary by +/-3%. In practice they vary by much
much less than that. The error is cyclic, i.e. over the span of a
full revolution, a "wobble" if you will.

You can easily prove this to yourself. Stand a motor on its end so
the shaft is vertical. Superglue a 1/2" by 1/2" mirror sliver to the
side of the shaft. Use a laser pointer and bounce the beam at a right
angle from the mirror to a wall about 10' feet away. Mark the
projected laser spot with a pencil, step the motor and mark the new
laser spot. Repeat this a few times.

There will be much less than a 1% difference when you measure the
distance between the pencil marks.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<davemucha@j...> wrote:

>
>
>
> As I read that, it seems they are saying that even though the
> calculation says the current should be 98.1% of the fla, the motor
> error is 3% and this it is not worth chasing.
>
> Dave