Re: [ATM] ground ring diameter vs. mirror diameter

[Dave Smith <smithersscope@yahoo.com>]

Hey Y'all,
John is correct regarding his comment of my plan. The
advantages of thin mirrors include light weight
(obviously) and quicker cool down times. One
disadvantage includes light weight! If you have a 16
inch f5.6 mirror like mine (focal length almost 90
inches!) you can't go building a minimalist
scope--even with Tom Krajci's virtual counterweight
system, springs can only compensate for so much weight
above the cg of the OTA! My first iteration works, but
I don't like the way it performs near zenith (as has
been mentioned this week on the list on a thread
regarding bearing surfaces). And my first iteration
wasn't compatible with motorizing. Thus, the rebuild.
I've also learned that an exposed mirror (i.e. no
mirror box) is bad for me. I'm not THAT clumsy, but
when I found the cat sleeping on the towel/dust cover
covering my mirror I got a bit anxious. I need the
weight on the bottom of the OTA, so I'm building a
more sturdy mirror box and perking up the handling of
collimation. Might as well replace those lead bricks
with something useful! ;O)
Thanks again everyone for the contributions!

Dave
fyi the first iteration is at:
http://dsmith.no-ip.org/smithersscope/atm/tridob.htm


--- John Sherman <atmer@johnspics.com> wrote:

> 
> 
> Hi all,
> 
> >Check out Greg Babcocks 24 inch scope with a
> >32 inch ring.  That is a 1.3 ratio.
> 
> Yes, a beautiful scope. A 1.3 ratio is good for a
> minimalist scope. But Dave
> said he's enlarging his mirror box to put the truss
> mounts inside. That is
> also the way mine is constructed. It results in a
> larger ground ring. Having
> an ultralight top end results in a smaller ground
> ring. As long as we all
> abandon the old-fashioned way of doing it, itz all
> good!
> 
> Oh, and since Mike NEVER searches the archives
> <chkl><chkl> I'll post this
> link yet again....
> www.johnspics.com/hi/flexiblerocker.jpg  The rocker
> has been modified for a
> few reasons. It now has skateboard wheels instead of
> Teflon pads, etc, like
> I described before...
> 
> John
> 
> 
> 
> 
> 
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 


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