Re: [ATM] Grinding/ Polishing slumped blank

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

Don't be too particular about the sag. you get.  you can easily
make the glass go either way for sag. without any problem.
Remember that it is where the forces are that determine where the
glass is removed.  Spend your time on the edges and you can
really flatten out the glass a long way without any trouble but
time.  You could also dig the hole in the glass from the flat
glass although you will then be a third of the way tthrough the
glass in the center which is why you are wanting to slump the
glass so that  you don't have that problem.
A good mold with no dust on it will make a surface that will be
able to be started at 320 grit while rougher surfaes and ROC
changes of any note wil be wanting up to maybe 120 grit to start
with.  I've stated molded surfaces at 25 micron grit but that was
a bit long with about 20 wets to get all of the glass in the
ground condition.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net


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