Re: [ATM] reducing mirror weight by sandblasting

[Dale Eason <atmpob@yahoo.com>]

Dan,

I think what ever weight you save will be offset by
the 27 point mirror cell.

Dale Eason

> I know it seems crazy to lighten such a thin mirror,
> but I am working on a 
> portable scope design where an extra 2-3 pounds
> makes a big difference.  I 
> should also clarify my previous email --  I am still
> in the design stage 
> and haven't ground or polished (or purchased) the
> mirror blank yet.   Any 
> sandblasting/etching would be done before polishing.
>  I am also not 
> committed to 1/2" yet -- with material removed from
> the back, a thicker 
> blank may be necessary to sufficiently stiffen the
> mirror even with a 
> 27point cell.  Ideally, I'd like to simulate the
> mirror with FEA software 
> and see what kind of deflections I get with
> different cavity and support 
> patterns.
> 
> 
> >If you really really wanted to cut pockets like
> this I would think a 
> >diamond bit cutting CNC machine would give more
> precise control for depth, 
> >etc.  But I still can't imagine it's worth the
> effort.
> 
> 
> A milling machine might be the way to go.  I have a
> little Sherline, but I 
> never thought of trying to cut glass with it.  I am
> worried that the 
> process would stress the glass too much, that the
> shards of glass produced 
> would be very difficult to deal with in my workshop,
> and that the diamond 
> bit would run me a fortune.
> 
> :Dan
> 
> 
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