Re: ATM Aluminum, Split Ring, Astrograph

[Andy Saulietis <iss@pvtnetworks.net>]

Dave Roew write,

>Anyway, here's the question.  I have found over the years that a friction 
>drive is great for astrophotography, very smooth, very low periodic error, 
>etc.  So, I want to make a split ring equatorial for this puppy.  A wooden 
>split ring in this size is doable, but very heavy and not as strong as one 
>would like.  I can envision an aluminum split ring about 1/2 inch thick and 
>maybe 30" in diameter.  I can also envision making this out of plate stock, 
>machining holes in the plate to remove unnecessary material.  Or, I guess I 
>could weld together a complex split ring and then have the ring machined 
>round.  Or...

I use 1.5" (and heavier) steel angle, attached to
plywood, to make large diameter rings for alt-az
mounts, up to 60" diameter. The rings are
set up on a rotary milling table and a high
speed grinder used to true the diameter (or
flat end). I have not used this technique to
make split rings but there's no reason these
wouldn't work also.

The rings can be rolled circular by outfits
that do storage tanks etc. The cost is usually
pretty low, <$100 to a 60" ring. The rings
can be welded to be continuous. Typically
the rings are circular/flat to ~1/8".


Andy Saulietis
ISS Enterprises
39 Silver Fox Trail
Mayhill NM 88339
505-687-3067 voice
505-687-3021 fax, call voice or e-mail to set up
e-mail: iss@pvtnetworks.net