Its aluminum. The bending certainly isn't that much. I centre punched the bolt and drilled a small hole first. The bending I'm refering to is perpendicular to the rotation angle, so should affect accuracy too much -- it will make the encoder appear to trace an eliptical path rather than a cirle. There are so many other errors to contend with also like perpendicularity of the mount, selection of alignment stars, etc. I use ECU with my Micro-Guider and usually "sync" on the area of sky I'm interested in and get good accuracy.
>Unless you have a well equiped machine shop, it is probably a good idea to
>buy a bolts with precisely drilled holes. All the digital setting circle
>distributers sell them in their mounting kits.
Agreed. I had one of the kits from Astrosystems for my new 17.5" I'm building (if I ever get a mirror), but I retrofitted the encoders to my 13.1"...Dave
-- David J. Lane, Astronomy & Physics | E-Mail: dlane@hercules.stmarys.ca Saint Mary's Univ., Halifax, Canada | WWW: http://apwww.stmarys.ca/~dlane/dlane.html "The Earth Centered Universe" home page is at http://fox.nstn.ca/~ecu/ecu.html