Re: [CAD_CAM_EDM_DRO] Re: breakout boards plus - hard choice

At 09:23 PM 7/19/2007, you wrote:

> > If I understand it correctly, current stepper and servo drives
> are all unstallable in a sense, that they allow a certain following error.
>
>This is not true for steppers. Any lag greater than 2 full
>steps guarantees at least a loss of one full cycle=4 steps, and
>unless it happens at dead slow speed it will cause the motor to
>stall completely.

Actually this is not accurate in a microstepping environment. In a
half-stepping environment each step is 1/4 of the cycle. Two steps
plus the inertia will allow the motor to recover quite nicely if the
load drops off a little. In a microstepping environment there may be
10 or 16 steps for the same cycle, in that case, an error of some 5
or 8 steps can occur and not cause a loss of synch or stalling.


David G. LeVine
Nashua, NH 03060