Re: ATM magic glide and alt-az bearings

[Michael Lindner <mikel@att.net>]

Nick Cain wrote:
> 
> Will any ol' floor laminate do?

In my opinion, it depends on the weight of the scope you're building.
For my 6" dob I used a "granite" countertop laminate (not knowing what
ebony star was). It has a pebbled surface about as rough as a cloth
bound book (but of course, made of formica, not cloth). The true ebony
star is much bumpier, more like a surface with paint splattered on it.

My 6" works well, and others who have very light scopes who have used
true ebony star have told me that mine has smoother motion than theirs.
Of course, for a larger, heavier scope, the ebony star seems to be the
best (and Kriege writes that you want even bumpier stuff for very heavy
scopes). Your mileage may vary.

> Also, the magic glide disks are shaped like a flattened hemisphere, is it
> worth grooving the part of the rocker that the pads will run along, to
> perhaps stop the telescope slipping sideways?

If you mean the azimuth bearing, don't bother - the center bolt will do
that. If you mean the altitude bearings, you may want to put a ridge on
either the inside or outside edge of the bearing to help limit sideways
slipping.

--
Mike Lindner