Re: [CAD_CAM_EDM_DRO] Geckos, Servos, VFD and twitching on Z axis

How close to the Z-axis controller to the VFD? Maybe the
electrical 'noise' is causing problems. Are you using the
quill as the Z, or are you raising & lowering the table to
effect a Z-move? Is your ram rigid enough to prevent it's
movement under power? Does the 'drifting repeat itself
with any kind of regularity, under load? These are all
things I'd take into consideration in troubleshooting.

RayHex

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> From: yethdear0 <da-mack@...>
>
>
> Hiya,
>
> We have an old Hurco knee mill that we have stripped and

retro-ed

> with a pc, CNCPro, Geckos and a Baldor VFD for the

spindle motor. We

> just got it all up and running but have a problem with

the Z axis

> servo or controller. Using a travel indicator on the Z

axis, the

> movement is smooth and exact. We have the machine running

a program

> that move Z -.100" pauses for 1 second and then moves Z

+.100" and

> then runs in a loop. When we turn on the VFD and the

spindle, the Z

> axis seems noisy and the travel on the indicator will

start to

> drift .001" to .005" each time the program cycles. The

drift is

> random, sometimes positive and sometimes negative but

positive the

> majority of the time. When we slowed the motion to 1 ipm,

you can

> see the motion twitch at random during the movement. This

only

> happens when the spindle is running and only the on the Z

axis. We
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