From: David Margrave 
To: atm{at}shore.net
Reply-To: David Margrave 



I have worked backwards from my goal of completing the 8" refractor,
and realized I have a bit of additional work to do!  But that's okay, I'll
learn a lot in the process.

For testing my 8" lenses, I'll need an optical flat, I figure 8 or
9".  I have a rough understanding of the method for making optical
flats with three blanks, but unfortunately have found a shortage of web
pages in this area.  I have texereau's book which I'll read up on.

In one internet posting, I heard it alluded that you could make a flat with
just one blank, and with two metal tools in place of the other two blanks. 
Has anyone taken this approach?  Seems like you could achieve some cost
savings in this area.

Also, to test the flat without another flat, I'm going to need a long focal
length spherical mirror as I understand it.    I could have a lot of glass
lying
about by the time I'm finished!  But I have ideas for the extra flats if I
go with the three glass blank approach:  front surface mirror for 45 deg.
bino mount, and possibly a flat to make my refractor a folded design.



Thanks,

Dave


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