Polishing the Mirrors
The standard polishing stroke is the same as the standard
grinding stroke. Polishing takes a lot of patience. Unlike
the grinding operation that can be done by machine, this stage is better
done by hand. We had done some of the initial polishing with the
machine, but the process started to seriously slow down as we progressed
with the polishing. There is a lot of friction between
the lap and the mirror once the mirror gets sufficiently smooth, and this
led to a minor disaster when one of the rubber bumpers on the alligator
couldn't take the stress and fell off which allowed the mirror to fall
off the tool while weights were on top of it and while no one was looking
as the machine did it's job and we were all in the other room and this
led to a loud crashing sound which nearly led to four simultaneous heart
attacks........ There was some damage to the lap and a few
scratches on the mirror which we hoped we could polish out without having
to go back a step or two....We decided to use the machine just as a rotating
platform and do the polishing by hand.
John Mahony is using the machine as a rotating turntable for his hand polishing.
We also made a second tool and started polishing both mirrors at the same
time. One on the machine and one clamped onto a desk. This
will allow both mirrors to progress at the same time. After switching
to hand polishing, we progressed as much in two weeks as the prior two
months worth of machine polishing.
Ed Harfmann is shown taking a short turn at grinding. (He's usually
trying to update these pages....)
These pictures were taken in the early stages of polishing when we were
using white polishing rouge. We eventually ran out and switched to
red rouge (slower, but better quality polishing). Red rouge is simply
extremely fine particles of iron oxide, aka "rust". This is the same
material used in cosmetic rouge. The universal staining effect of
red rouge eventually caused our work area to be compared unfavorably to
a slaughterhouse in appearance.
Once the mirrors started to become reflective we could check the accuracy
and quality of the surface figure using a Foucault
Tester...