Re: Gecko's don't like 7 x 10 (stepper resonance)

Lee,

At the risk of over simplifying, a stepper motor behaves like a
spring/mass system with respect to resonance. Adding a mass would
lower the resonant frequency rather than eliminate it. This is
sometimes done to good effect on lathe tooling. A mass is added to
the tool to reduce chatter during a particular cutting operation at a
particular speed. Adding mass to the stepper shaft may stop this
specific instance of resonance, but in general is not good as it adds
to the inertia that the stepper must overcome and will reduce system
performance.

There is a concept of adding a mechanical device to a stepper to
reduce resonance, however this device is a damper. Typically they
consist of a mass coupled to the shaft by a viscous fluid. The energy
loss in the fluid provides damping much like a shock absorber in a
car.

Your problem could be resonance in the stepper motor, or less likely,
resonance in the machine structure. Adding mass could help you figure
out which it is. If it is the stucture, then you can try to stiffen
your machine. If it is in the stepper you may have to experiment with
different motors or drive techniques. The Gecko drives provide
microstepping and mid-band stability compensation. The microstepping
should reduce the motor's tendency to resonate at relative low
speeds. Have you tried adjusting the mid-band stability settings?
Reducing the drive current can also reduce the resonance severity if
you can do this and still have enough power for your application.

Regards,
Steve Stallings

--- In CAD_CAM_EDM_DRO@y..., "studleylee" <indigo_red@q...> wrote:

> Would adding a mass ( or flywheel) to the stepper pulley help
> or hinder stepper resonance regions? Any Rule-of-Thumb's (ROT's)?
>
> -Lee
>