131029

131029 Telescope Workshop notes 730-9p Tuesday evening
Attendees:  EdK, TomT, TomW, JerryW, Tim & ColeenC, TomK, ChrisU

TomW pouring a new 11 inch pitch lap tool for EdK as the previous 9 inch was contaminated.  TomW put together the wood disks provided by EdK and filled and sealed the surfaces to be waterproof.  The pitch tar and wax was heated in the small pan on the little electric heater and carefully poured into the 12 inch square silicone form (see http://sbautw.blogspot.com/2013/09/130924.html) laying on top of the mirror blank protected by heavy paper towels to almost the edges, leaving room to avoid the pitch spilling over the sides of the form.  The wood disk was placed on the hot pitch and a jug of water placed on top to form the pitch shape to the existing mirror blank in need of repolishing. 

 The form, which had been sprayed with TomW’s release solution of isopropyl and ?, came off nicely, with some air bubble imperfections in the surface of the pitch.  After cooling for 30 minutes, cerium oxide polishing solution was applied and polishing was started with long slow strokes.



TomK brought in his Astrosystems, Randy Cunningham, Dobsonian tube mount for a 12.5” mirror.  Cost about $1250, but with a dual speed focuser.  http://www.astrosystems.biz/ 







Several boxes were brought in, without the truss tubes or wheel barrow handles.  He will be getting a lightweight mount from a Hawaiian source, so he is willing to sell this one.

TomT brought in EasyTesters, eyepiece devices to check telescopes for mirror distortion and collimation.  Jerry was interested in the Ronchi eyepiece which needs to be pointed at a bright star, but the Easytester II is a collimator that goes dark if collimation is reached, which is not his preference for that. http://schmidling.com/ez-testr.htm  Cloudy nights has a negative review of the EasyTester II collimator: http://www.cloudynights.com/ubbarchive/showflat.php/Cat/0/Number/1860801/Main/1844127 and recommends the ones at Astrosystems.

Photos/vids here: http://www.flickr.com/photos/27241501@N03/sets/72157637360891894/