Re: rotary encoder versus glass scales

Sometime ago I've got to fix a pcb drilling machine, it would drill
a few holes then stop for no reason, after about an hour I've found
the problem,it was that the ballscrew had some play on it (backlash)
and the glass scale just could keep up with that, fitted over size
balls on the ballnut and it works nice again.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "alphawolf45" <haushahn@c...>
wrote:

> I am in the process up gathering info and parts to upgrade an old
> Hurco Bedmill to PC controls.I have ripped all the old electronics
> off the machine cept motors and limit switchs ..I have new servo
> drivers in hand and just gotta get a coat of frsh paint on the
> machine and will be ready to wire something up....Cleaning on the
> machine today I found that the X-axis motor's rotary encoder had

been

> disconnected and somebody had installed a glass scale on backside

of

> the bed for that axis.Reckon I should try to find a new rotary
> encoder or is the linear scale gonna be alright? I been reading

about

> rotary optical encoders but havent a clue at the electrical
> differences between them and the linear scales..I want to keep

this

> simple where I can and save the sweat for the worthy
> problems..Hehhehehheh
> Then another question if somebody wants to take a stab at it is
> why did the old controller make use of a tach signal from the
> servomotor and these PC run conversions dont use that signal?--Or
> maybe they do and I havent got to that part of the reading
> materials..This is my winter project and I got a lot to learn yet.I
> figure this isnt the last time I'll ask questions here.
> Thanks
> Steven