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Hi Stefan
Thanks for your interest.
I actually only used two laps. For most of the work I used a slightly oversized lap. It’s about 6 mm wider than the mirror. I followed Mel Bartels advice a bit on this project. I’ve used slightly oversized laps before and found they do help to prevent turned edge.
To deepen the centre I used a chordal stroke. To extend the correction out I used a long centre over centre stroke. This left the intermediate zones lagging. I used a 4 inch lap with a tangential stroke to address these zones. The end result led to a slightly over corrected mirror. Fortunately some gently W strokes tool on top brought the correction down again and smoothed it out a bit too. It sounds straightforward but it wasn’t! I had to return to spherical twice after over correcting the outer zones. It took me several months free time to find a combination of strokes that worked. I kept a log which helped a lot. I did try a 2 inch lap at one point and found it created far too much roughness.
Virtually all the figuring was done by hand with the machine acting as a motorised turntable.
Rod
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