RE: [CAD_CAM_EDM_DRO] I'm curious

If I may be so blunt, you're missing the point. A telescope worst enemy is
backlash and hysteresis, we have one worm gear per axis period. This means
we have one source of backlash in the system that we can control and
maintain. A telescope is like a machine tool in this respect, when we change
direction we want it +/- 1 arcsecond, though I admit our tolerances might be
a bit excessive.
As for servo drives with high encoders; you now understand why we use
steppers.

Jack

-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of David A. Frantz
Sent: Thursday, July 21, 2005 11:07 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] I'm curious

I'm not sure where you get the idea that reduction = backlash. I
worked on diamond turning lathes for years, several models in fact and
they all had belts between the motor and leadscrew. Every one of them
was a servo driven system and the belts where there for resolution.
Gearbox / belt reduction free systems are certianly possible, especially
given the explosion in equipment and manufactures, but they are not
cheap systems by any measure. Plus the idea of directly driving a
telescope axis with a motor large enough to do so is a bit unsettling.

If you are up to speed with respect to issues related to micro stepping
then why all the complaints about Geckos? I'm really trying to
understand your desires. Do realize that if you go with a servo drive
and encoder feedback you would need an encoder with very high
resolution. That sort of hardware is hard to find and expensive.

Thanks
dave