Re: [ATM] Rough generating blanks

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

Depending upon the quality of the diamond grinding, you may need
to start from anywhere like 220 grit to 25micron.  The plaster
tool method works fine and at 320 grit, it will take about an
hour of grinding to get the tiles mostly in contact with the
glass.  Don't worry about hollow center parts of the tiles as you
don't need to have 100% grinding surface to do the work needes.
Get it ground to F5 if you want F5 and don't worry too much about
the ROC shifting as flipping the two over will work it the other
way nicely.  If you do flip, do at least two wets that way to
insure that the curve settles down at the new positioning.  You
don't want to do the long curve generation strokes but rather the
shorter 1/3 or less strokes with a slight W to them.  This will
tend to keep the glass spherical and pretty much stop the
changing of the ROC.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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