131022

131022 Telescope Workshop notes 730-9p Tuesday evening
Attendees:  EdK, TomT, TomW, JerryW, DmitriiZ,TimC, ChrisU

EdK- Stuff happens.  Was polishing his 12.5” mirror for three more hours at home with the 9” pitched tool made by TomW.  However, short scratches in surface were detected and EdK’s Foucault test at home was fuzzier.  TomW thinks polishing compound was either contaminated or somehow Al2O3 compound was used instead of the CeO2. TomW says to dump the contaminated pitch lap tools, because DmitriiZ is having surface problems with his mirror polishing also. Laser check of mirror surface by TomW shows most areas even less specular; the light at the outer area is very wide compared to the inner area of the mirror.  TomW set up Ronchi tester for EdK to check the mirror as well.  At inside R, it showed very different pattern than before. 

JerryW suggests randomizing stroke further by flipping mirror and tool periodically.  He is suggesting larger pitch lap tools as well to avoid working mirror surface unevenly.

TimC continued with grinding at 220 grit on the 8 inch donated mirror blank.  The tiled tool was catching on the edge of the mirror with its plastic ties sticking up between the tiles.

Books in class tonight: Dmitrii returned ChrisU book “Seeing the Deep Sky Telescope Astronomy Projects beyond the Solar System”, TimC brought in the “Apollo Expeditions to the Moon” book.

ChrisU brought in orange (flaming tomato!) painted Dobsonian base.  TomW recommends contact cement to adhere Formica bearing surface.

TomT brought in EasyTesters, eyepiece devices to check telescopes for mirror distortion and collimation.

More Photos/Vids here: http://www.flickr.com/photos/27241501@N03/sets/72157636950662963/