Re: [APML]: ATM question

[DROWESMI@aol.com]

In a message dated 98-02-20 15:21:16 EST, you write:

<< Anyway, sorry for the long post, but if anyone can find the time to give
 me as much info as possible in this project, I would greatly appreciate
 it.
 
 Thanks,
 Jim Fedina >>

Jim:

I bought a 10" mirror for my first scope and I am now making a set of optics
for my new project (an SCT).  I am really having a wonderful experience making
the optics.  So, if you are patient and don't have to have your first scope
right now, then I recommend that you try making an 8" mirror.

I have made two different arangements for my 10" mirror.  In the first, I made
a wooden tube using 1/2" plywood, cutting and gluing the wood into an
octogonal cross-section.  The tube was very beautiful but too heavy.  On my
second attempt, I made a truss tube structure out of 1" diameter aluminum
tubing and a plywood end section.  The mirror housing was octogonal (a piece
sawed from the original tube!) 18" long.  This structure is much lighter and
has much, much lower moment of inertia, which is very important for quick
damping of vibrations.  The new mount that I made is a split-ring equatorial.
You probably don't need a split-ring for an 8" mirror.  A good begining mount
which is easy to make is a light-weight but strong Dobsonian.

Hope this helps,
Dave Rowe
Torrance, CA