Re: [ATM] Coolling fans for mirror

[Curt Diggs <mokiman_210@yahoo.com>]

Another substitute for the detested rubber bands (me, too) are thin strips cut from a small piece of 1/16" of rubber gasket material from the hardware store (or home improvement store - look in the plumbing section). Couple of bucks for a 6" x 6" piece gives you enough strips for several telescopes. Works great and there's no visible vibration at the eyepiece even at high power.
   
  Curt
  
>Hi Dale,


> Usually we want to cool the mirror to ambient as fast
> as possible so that we can get the best view soon.

>Absolutely!

> Overall a single small fan
> supported on rubber bands aimed at the back of the
> mirror is a very good way to cool the mirror quickly
> and has been used successfully by many.

>It's my favorite way of ventilating. Also it takes advantage of the tendency 
>of heat to rise. But I hate the rubber bands, they quickly dry out and fall 
>apart. I now use a sheet of felt. They are in craft stores, about 12" x 12" 
>x 1/8". I cut a hole in the center and mounted the fan to it with little 
>bolts, then screwed the corners of the felt to the mirror box. I also attach 
>the switch and pot to the felt, with all the wiring hidden inside. It 
>deadens vibrations better than rubber bands, and it lives much longer. Also 
>it helps prevent a backwash of air (so that air is forced around the mirror 
>and up the tube better), and helps block light from entering the back of the 
>tube.

>Happy observing,

>John




       
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