Latest progress report as of 2/14/2018.
I did about two hours by hand with the spin polishing machine rotating about 3RPM. 90% diameter tool. Ten minutes polishing with 1/3 to 1/2 COC strokes mostly over center. Ten minute cold press and then repeated. Alternated sessions with TOT and MOT. Used 10 lb weight when tool was on top. About 30 strokes per minute. Did these cycles for a total of two hours. 12.4 inch diameter mirror, 125.4 inch ROC, and f/5.
This is a Foucaultgram slightly out beyond ROC:
This is the Ronchigram out beyond ROC to about 0.37 inches:
I went back to the spin polisher. All TOT. Started with 20 minute warm press. 10 minute spin followed by 10 minute cold press. Machine running at 40 RPM. About 30 lbs weight. Moved arm so tool center rotated over 10% to 90% of mirror radius. Cycled back and forth by hand at 3 second period. A slurry of CeO & water.
Here is the knife edge about 3/4 inch inside ROC with diffused LED light source:Knife edge at about same point as above but with unfocused/non-lazing laser point source:I used zoom to get a closer look at that edge above:Foucaultgram just slightly beyond ROC.Ronchigram out beyond ROC to about 0.37 inches:
Should I keep working to reduce that edge? Should I work on getting it closer to a sphere? How?
That looks like good progress to me!