Re: [ATM] Flat grinding the back of the primary mirror

["Bob May" <bobmay@nethere.com>]

Generally, the back is ground flat to make it flat realtive to
the lump that you got with many of the blanks that were (and
still are) sold.  Same thing with the sides of a piece of glass.
Grind to the level that you're comfortable with - I'd consider 25
micron to be fine enough for any purpose.  Stuff thatt is already
polished really doesn't need to be ground as it is already
flatter than is necessary.  You don't gain anything by grinding
the sides really in value of the mirror unless it really is a
lump of glass that you used.
Bob May
bobmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
Replace the obvious words with the proper character.

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