Tuesday, August 27, 2013


130827 Telescope Workshop notes
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/

Wednesday, August 21, 2013


130820 Telescope Workshop notes
Attendees:  EdK, JerryW, TomT, DmitriiZ, TimC, TomW, ChrisU

EdK-brought in 1968 pyrex 12.5” f/5 mirror blank  (also w/ couder disks  http://stellafane.org/tm/atm/test/mask.html) that had been polished and TomW set up his tester (1/4-80 threads on adjuster!) for Ronchi test and  resultant patterns in and at focal length.  TomW's verdict was center of mirror was not quite deep enough for perfection, but edges look good.  Foucault knife edge test did not show the problem in the center as well.   TomW recommends 6” tool to work on center to deepen it.  TomW will bring in a calculated Ronchi pattern chart from the focal length of 127” to use by EdK for finishing the mirror.

TomW says edges good

TimC-continued work on donated 8” mirror blank grinding to f/5 with 80 grit still.  Many “wets” or “charges” of the grit was used.  When the measurement of the sagittal, depth, is satisfied the smaller grits will be used.
TomW-brought in another crisp, this time rubarb, apple, peach, strawberry…delicious again.
ChrisU-has been looking for mirror blanks prefinished on the internet; JerryW recommended Cloudynights.com for its classifieds.  TomW showed him the tester and pin sticks describing the percent of light gathered at each pin distance across a mirror.
JerryW-has been working on his 10” Cassegrain, 14” Dahl-Kirkham, and 18” Newtonian at home…all have the grinding stage done.  He is currently grinding the 6” spherical secondary for the Dahl-Kirkham.
See all of tonight's photos and videos of mirror here: http://www.flickr.com/photos/27241501@N03/sets/72157635163404065/

Sunday, August 18, 2013


130813 Telescope Workshop meeting minutes August 13, 2013
TimC, TomW, JerryW, EdK, TomT, new member Christopher Ulivo (SBCC Art Prof) [see:  http://christopherulivo.com/ ]

 TC-Astrovaganza went well at the Broder Bldg, August 10, but Powerpoint timing seemed off and was not viewed that much.
TW-shared his large homemade apple crisp...delicious!

TC-discussing telescope making w/ CU, who is more interested in building the telescope mount than grinding out a mirror.

JW-using Edmund spherocity tester on his corrected Dahl-Kirkham secondary mirror.

JW-also showing Moonlite telescope accessories Dobsonian truss mounts to EK.
TC,TW-grinding 8”  donated mirror (80 grit) and TC describing  depth needed to CU.

JW-showing CU that firsthanddiscovery.com sells mirror kits w/o tool

130722 TimC Subject: Tinkerers' Faire

 130722 TimC: Subject: Tinkerers' Faire

I just wanted to send a big shout out of THANK YOU!!!!!  all of you who 
participated this past Sunday. I think it was a big success. We may get 
some hard numbers of the attendance sometime in the future. I will guess 
we had at least 400? I know some of you had to make arrangements or 
didn't feel tip top that day. I really thank you for making the effort 
to coming out. Justin C did a great job in organizing this event. 
The walk in with the carts was way easier than I thought it would be. I 
actually got all my stuff on one cart (almost). Javier was great to make 
arrangements for us to pick up the monitor. Dmitrii, I thought the 
presentation you created was perfection. I hope we can do it again this 
coming August for the Astrovaganza ( or someone can run it.). The 
pictures on the monitor were worth not having to explain certain aspects 
of mirror making and more. Customers could see it. Tom K said he had 
a whole bunch of kids. The idea to set up on the nearby bench was truly 
a good match for these little ones. Joe D was so helpful that day to 
me his help was indispensable. The prank to have the front desk ask me 
for I.D. was actually a good one. You got me. Tom T was a floater 
as well as Ed K. Tom thanks for handling the hand outs for me! 
Having free floaters I believe is a must.  Tom W. and Jerry, what can I 
say? When I have any hard questions come at me, I automatically turn to 
find you two. Couldn't do it without you both. Hope you are feeling 
better Tom. Jerry, thanks for going the extra mile for us. Give Pat our 
best!( The dog needed a day off anyway;-) ). I was in the classroom with 
Jerry and mentioned how disappointed not having my good buddy Ed Edwards 
' there was. I was really looking forward to him giving his take on old 
school amatuer astronomy to the customers. Jerry told me," You never 
know, maybe he got the message and he will be here any moment." Two 
minutes later, he walked into the lunchroom! Thanks to Gary R for 
dropping everything to help us get Ed's scope into the canopy area! 
Gary, I hope you got to see the Tour final stage that evening. (You too 
Ed K.) The visuals on the Arc de Triomphe were just the best!!! Last but 
not least I want to thank the AU for letting us use the new monitor. I 
will tell you, it was not money spent in vain! It is really cool! Just 
the right size! 
We will do it all again this August if any of you are up to it. Next 
month, I think we will be at the Broder Building to set up our 
presentation. Personally, I hope you can make it. You guys are just 
great. I was watching. I'd put you guys up against anyone, anytime, 
anywhere. Period.