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...