"Lloyd E. Sponenburgh" wrote:

Ignoramus21167 fired this volley in
:


Your accuracy number for my example was 0.02".

If you increase the count by 3 times (as in your mention of 2,000 CPR)
then the accuracy only improves to 0.006", also an unacceptable
number.

Something is not right.

Thanks for doing the math, Iggy.

Bingo! You win the big teddy bear.

If a servo misses re-positioning 128 (or 256!) times in a full stroke of
the machine, it's undersized, or being driven too fast.

I have a couple of machines that would upchuck if they detected TWO
missed steps in 38".

LLoyd

You're confusing cumulative error in a stepper system with the
non-cumulative following error in a servo system.

A servo system needs fine encoder resolution so that the servo loop can
function properly and hold position against loads. The max following
error is the point that the servo will alarm and shutdown. If the system
is designed correctly, 128 counts should translate into something like
1/10 of the nominal position resolution of the system, like 0.0001" if
you expect to utilize 0.001" positioning.