[ATM] How to do this right

["David Williams" <dwilliams1128@earthlink.net>]

Hello ATMer's

I am David Williams the one with the 20 inch Newtonian telescope, and I have decided that I have hyperbola in my mirror.  But also I need to support my mirror in a better way than by just setting and resting it up right (with the edge on the ground).  This way would want to introduce an effect where the mirror tries to slump over on itself.  And we don't want that.  So what we need is a sleng holder like a piece of carpet that runs down and around the bottom of the mirror to support it evenly.  How this will work in a telescope mount where the edge of the mirror is constantly shifting around as you look at different sky objects, I don't know.  Does anyone here understand this?  Also I need a floating point mirror cell (some people call it PLOP).  I'm half way there since I have some sheet metal that is 1/8" thick, and some hammered up sheet metal that is 1/4" thick.  (the latter is good for small pieces, for larger pieces you would have to either run it through a roller to make it smooth again or buy stock).  

I have a couple of new pictures that deal with my 20" telescope.  Here's the link:

http://www.atmlist.net/uploads/index.cgi?action=panels;left=/20%22Telescope%20Stuff/;right=/;order-left=name;order-right=name

click on   20InchFrameWork.jpg  to find a picture that shows the way I stiffened my 20" sonotube.  I used rings that I had cut out by some local amish with a router, and then I used lateral length-wise pieces of 1X3 pine to connect them (I used bolts and nuts) the bolts go all the way through the wall of the sonotube too.

Then I started to think that the idea of the Couder mask is a good idea.  You could test different zones at different times, so I tried to make a mask out of construction paper.  Also my friend Jerry says that I should use a pin hole test instead of the knife test.  The University Optics Mirro-Test foucoalt tester is setup to use two knife edges (one from each side).  So I modified it to use a pin hole that I pierced in a piece of aluminum foil.

Here's the picture of the Couder mask:

CouderMask20Inch.jpg

Thank you for  your help.

David Williams
Bye



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