Re: [CAD_CAM_EDM_DRO] machine inaccuracies fixed by software compensation

Carol & Jerry Jankura wrote:

> Doug:
>
> Isn't the 5% error rating on the motor the positional accuracy of the last
> step, and not cumulative?

Oh, its clearly NOT cumilative, the steps are built into the motor, and
barring losing a step, they will be quite repeatable. What we were
discussing is what the 5% is referred to. I still dispute the 5% being
referred only to the theoretical position of a step, as that means the
position is within 5% of 1/200 of a revolution, or .05 x .005 = .00025
or .025% of a revolution. That seems too high for a general production
device. I suspect there is a local cumulative effect, where slight
positioning or magnet strength errors in the rotor combine with slight
centering errors in the stator iron laminations to produce errors that
repeat every rotation.

Jon