Re: [CAD_CAM_EDM_DRO] encoder installation on servo drives

It is more of a packaging issue. It is often easier to fit the encoder
on the motor. Backlash in a toothed belt in reasonable condition is
negligible. Quite a few machines do fit the encoder on the screw. The
only time I have seen any problems with doing this was when the keyway
on the motor started to wear on a router. This caused quite violent
hunting as the control tried to compensate for the backlash. By the time
I got called in the key had received such a hammering that it was nearly
round!

Les

embedded_tom wrote:

> I asked this on cnczone, but no replies. So...
>
> I've noticed that almost all the servo-based setups I've come across:
> 1. Utilize a belt drive to connect the servo to the leadscrew.
> 2. Place the encoder on the servo.
>
> I understand the reasoning for the belt drive, but wouldn't it be
> better to put the encoder on the leadscrew shaft?
>
> In other words, doesn't the belt drive add some backlash effects with
> the encoder on the servo?
>
> Or does the slop help prevent servo hunting when there's no motion?
>
> Thanks.
>
> tom
>