From: "Kreig McBride" 
To: "Shane LaPierre" 
Cc: 
Reply-To: "Kreig McBride" 


Shane,

You can finish the outside of the tube in several ways. A polished aluminum
tube would be awesome but an incredible amount of work and the surface is
easily damaged. Also not the best radiator of heat.

Paint,  you can buy water based aluminum primer, and apply with a brush.  A
little care will give you a good finish and then any paint you want to use.

Interior, you can use a flat black paint. Try to install one or two baffles
if you can.  Probably just 1/8" rings to cancel out the low angle
reflected light.   Since the tube is small compared to the mirror size, you
might have
thermal/convection problems, so a cross mounted fan will help tremendously
for cooling a stabilization.

Third you can cut the tube to about 1/2 to 1/3 of the original design
length and hang a truss on the end.

Fourth, you can cut out sections that dont look like a truss and you end up
with a . . . . truss.

The fifth option is to throw out the tube and try somethig else.

Kreig


-----Original Message-----
From: Shane LaPierre 
To: atm{at}shore.net 
Date: Tuesday, March 04, 2003 8:54 AM
Subject: ATM Fix up an aluminum tube


>
>I have an 8" newt that's in a truss tube now, and I'm going to put it in a
>used piece of 9" diameter alum to make it a little more adaptable for
>imaging purposes.  How do you fix up the exterior of an aluminum tube?
>
>Also the actual diameter of the mirror is around 7 3/4" & the id of the
tube
>is 8 11/16".  That leaves less than 1" clearance which brings me to my
>question about finishing the inside.  I can either just repaint it flat
>black, or line it with cork... but there's not a lot of room to work with.
>Any opinions?  As far as thermals this thing is mounted full-time in a
>non-climate controlled observatory so it doesn't take long to cool off.
I'm
>thinking the cork will help insulate the optical path from my hands.
>
>Shane LaPierre
>http://www.geocities.com/stellar1972
>
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