Re: [CAD_CAM_EDM_DRO] Re: Okuma LB 15

"Daniel T. Hage" wrote:

> Thank you Jon,
> You are right, I think the problem is in servo-controlled spindle axis.
> I couldn't measure the RPM, I think the variation quite significant (more
> than 10%) since I can see the different speed.
>
> Do you have any solution?

Not really. Do you have manuals on the machine there? If no manuals,
it is nearly hopeless. With manuals, it may be possible to figure out the
problem. One thing I can think of is to get a tach - even a crude one, like
a small permanent-magnet DC motor and a DVM, and make a graph of
actual RPM vs. commanded RPM in each direction. If the servo drive uses
paralleled transistors, some of them for one direction may have burned
out. If the transistors are in parallel, they often have fusible ballast resistors
that sometimes burn out, too. Is this an AC servo, or a DC (brush) servo drive?
The AC servo drives generally will either work OK or fault. But, a DC brush
drive basically has a different set of transistors for each direction, so problems
there could affect only one direction.

If it is not blown transistors in the drive stage, then there could be some
adjustments in the servo tuning area that need to be reset. Again, manuals will
make this VASTLY easier to do.

Jon