Re: ATM 21" f/6 Rough Grinding Lesson Learned

["Bill T." <twentiethwave@hotmail.com>]

Ken Bertapelle wrote:
>>
FYI, here's an interesting discovery I've made while rough grinding my
blank.  I'm using a 14.5" diameter tool plated with metal washers and
working MOT with #60 SiC grit.  In the course of hollowing out the curve to
a depth of .08", I had come to the conclusion that the fastest I could go
was about .01" per hour of grinding.  But over the weekend I found a way to
improve this by about 50% by 1) using a bigger charge of grit on each wet
and 2) mixing a little windex with the water I spray on the glass prior to
each wet.
<<

Ken,

Yeah, you got serious Cerium Oxide contamination in your 60 grit!  That is,
the theory that says "less is more" for polishing contanimated the "more is
more" reality of heavy grinding.

I have long thought that a small amount of wetting agent like soap (or
Windex) in the heavy grit wets helped spread things around so that the
un-crunched grits had a better shot at the glass.

Bill T.