Attendees: JerryW, EdK, TomT, TimC, TomW, ChrisU, DmitriiZ
TomW- brought in the actual book “Understanding Foucault” by David Harbour and TimC another book, “Making a Refractor Telescope” by Norman Remer.
TomW- also brought in his 8” concrete tube for his f/5, 6” mirror with his specially designed bearing wheel and cross supports that allow for the tube to slide within it.
TomW- continued polishing out EdK's 1968 Pyrex 12.5” f/5 mirror: polishing 45min the raised center with a 6” and wider motion this time. TomW set up the Ronchi tester, with the 100 line per inch grating, to check the mirror progress. Foucault test was done also. Center looking better, but TomW thinks a larger polishing tool is needed to correct the surface as a whole.
TimC-continued his work on the donated 8” mirror grinding to f/5 with 120 grit. TimC let TomT practice the grinding cycle/motions (1/3 over centers) with the mirror. Since proper depth has been reached, the mirror glass blank and the tool were switched bottom/top positions about every 3 grinding cycles around. At the end, TimC showed us the cleaned off surface of the mirror glass showing more evenly ground surface with his loupe. JerryW looked at it and says another hour is needed to get the surface pits more even at 120grit.
DmitriiZ- formed the pitch to his mirror and was continuing polishing his 12.5inch to improve characteristics.
ChrisU- showed us his paint grinding glass pestle that is used with a glass mortar. Chris also brought in and shared a tasty treat.
More photos and vids here: http://www.flickr.com/photos/27241501@N03/sets/72157635818957903/
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