Attendees: EdK, TomT, DmitriiZ, TimC, TomW, JoeD, Nathan Fields (interested in astrophotography)
EdK-brought in 1968 pyrex 12.5” f/5 mirror blank w/ Couder disks that had been polished and TomW set up his tester again to compare against his Ronchi patterns that he brought in for center and edge comparison.
DmitriiZ-working tonight on his 12.5”, polishing the center down, will test on TomW Ronchi tester. Still high in center and TomW trying to give ideas on how to polish out the center. Laser showed edge not polished out. TomW came up w/ idea to press pitch on mirror with a “washer of paper” at the edge, so the pitch extends a fraction more out in the center. That will have to be done every 15 minutes as the pitch wears down smooth again.
TimC-continued work on donated 8” grinding to f/5 with 80 grit still. Nathan observed the sagittal depth measurement with the drill bit and used the loupe to see the surface with TimC explaining. Depth is getting close to desired.
JoeD-brought in Amateur Telescope Making Journal books vol. 1 & 2 containing various articles. Also a book on woodworking to make chests and cabinets. EdK took them home to read.
See more photos, videos: http://www.flickr.com/photos/27241501@N03/sets/72157635269973582/
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