130521 Telescope Workshop notes, May 21, 2013
JerryW,EdK,DmitriiZ,TomT
TimC had emailed earlier about his creation of a few documents this week for future handouts at Tinker Festival, July 21, coming up. https://www.sbnature.org/content/186/file/FLYER_tinker_WEB.jpg
DZ did not have his mirror this week, so we just did table talk.
EdK told us about his 100 mile weekly bicycle trips, using an 18 pound carbon fiber bike. He mentioned how Schmidt Cassegrain scopes have the corrector lens made by pulling a vacuum.
https://en.wikipedia.org/wiki/Schmidt_corrector_plate
JerryW was asked about his current grinding status: he is working on his 18" moving to 120 grit from 80 grit. The grinding process for his simultaneous three mirrors will take all summer to finish, before moving to polishing stage. Cleaning larger grit from his tiles before moving to finer grit requires hours of scrubbing his tiles with a toothbrush.
JerryW talked about putting mirror on top of tool to prevent flattening of mirror, which happens when tool is used on top of mirror glass. Time to grind 18" vs smaller mirror is the same if tool is same size as mirror.
JerryW was asked about types of eyepieces: Plossel vs Nagler vs. Televue Ethos.
-Naglers are heavy due to multiple lenses
-Televue Ethos made by Nagler for wider field of vision?
-Plossels are OK, but be suspicious of unknown brands.
https://en.wikipedia.org/wiki/Eyepiece
Tuesday, May 28, 2013
130514
130514 Telescope Workshop notes, May 14, 2013
Attendees: TomK, EdK, JerryW, TomT, DmitriiZ, TimC, TomW, EdEd, JoeD, John/Shah
-SBAU 42” tv was on table in Broder, but needed remote to change source.
DZ-working on polishing mirror. Cerium oxide solution using new pitch poured by TomW using a silicone mold.
TW- brought in his testing equipment. Testing 6” mirror, F9, 108” test length across two tables tonight.
-Then 14.5” mirror of TomW put on stand. Ronchi patterns shown of desired final test pattern.
-Then DZ 12” mirror currently being polished placed on stand at 910pm. 106” test length. TomW calls the pattern an oblate sphere, needing to carve/polish out center more. Foucault test (razor edge) test to see the “two mirrors” more clearly. DZ and TT taking photos/videos of patterns.
TimC--re: Tinkerer Festival, July 2l: TimC has grinding stroke poster; EdEd pictures and 1950 style 4.5” telescope, old telescope making books; JW will bring another mirror blank and wood grinding stand, TimC will provide grit stuff; SBAU tv with looping videos of mirror grinding by DZ,TT.
JW, EdEd, DZ talking to John/Shah on how to’s of grinding & making telescope.
TimC&EdEd to TomT-centuries ago mirrors were polished metal. Then 1860 glass was coated w silver. Amateurs in 1950s would deposit silver precipitate onto their polished glass. Today, .99999 pure Aluminum is sputtered on, then a coating of SiO2.
Bill Clausen wants lights out and doors open to let out any flies that otherwise can set off Broder alarms.
Attendees: TomK, EdK, JerryW, TomT, DmitriiZ, TimC, TomW, EdEd, JoeD, John/Shah
-SBAU 42” tv was on table in Broder, but needed remote to change source.
DZ-working on polishing mirror. Cerium oxide solution using new pitch poured by TomW using a silicone mold.
TW- brought in his testing equipment. Testing 6” mirror, F9, 108” test length across two tables tonight.
-Then 14.5” mirror of TomW put on stand. Ronchi patterns shown of desired final test pattern.
-Then DZ 12” mirror currently being polished placed on stand at 910pm. 106” test length. TomW calls the pattern an oblate sphere, needing to carve/polish out center more. Foucault test (razor edge) test to see the “two mirrors” more clearly. DZ and TT taking photos/videos of patterns.
TimC--re: Tinkerer Festival, July 2l: TimC has grinding stroke poster; EdEd pictures and 1950 style 4.5” telescope, old telescope making books; JW will bring another mirror blank and wood grinding stand, TimC will provide grit stuff; SBAU tv with looping videos of mirror grinding by DZ,TT.
JW, EdEd, DZ talking to John/Shah on how to’s of grinding & making telescope.
TimC&EdEd to TomT-centuries ago mirrors were polished metal. Then 1860 glass was coated w silver. Amateurs in 1950s would deposit silver precipitate onto their polished glass. Today, .99999 pure Aluminum is sputtered on, then a coating of SiO2.
Bill Clausen wants lights out and doors open to let out any flies that otherwise can set off Broder alarms.
130507
Attendees: TomK, EdK, JerryW, TomT, DmitriiZ, TimC, TomW, JoeD
DZ-working on polishing mirror. TomW later discussed CeO
compound he was using.
JD- showing key type wooden reinforced box method for wood
base of a telescope. Two wood triangles
sliced and glued into corner.
TimC – An email was sent to TimC from JavierR on July 21
“Tinkers Festival” need for telescope mirror making demonstration table. Two stations grinding, ronchi test stand, EdE
to bring a 4.5 mirror & scope, EdE to have poster of things you can make,
has another mirror w/ hole, fast F-ratio, to fit one table. TomW to bring 8” dob, plus tester &
sonotube for shade to allow seeing of patterns in bright afternoon light, he
will test at home to be sure.
TimC has list of telescope terms to hand out, but may be too
much?
Williams Bell still has some pitch & grit. Newport Glass melts glass still &
provides pitch, grit. Haywood, east bay,
National Abrasives is where TomW can get grinding materials. Clausing? does mirror coating. JD-Spectrum was not so good.
TomW would show kids mirror focal length by shining sun at
awning to see spot vs. handing out drawing.
TimC to make a source of material handout. Also chart of types of telescopes that can be
made.
Chuck McPartlin may have SBAU banner to use or Justin Canty
may provide some identification for Telescope Workshop?
DZ-could have series of videos going in a loop. TimC could bring small monitor vs. big SBAU
tv that was recently purchased for the observatory.
130416
130416 Telescope Workshop notes, April 16, 2013
Attendees: TomK, EdK, JerryW, TomT, DmitriiZ, TimC
-Jerry, re:Ed friend Schmidt camera? mirror, talking about
auto collimation test vs collimator and Foucault Test. Point light source down
thru eyepiece thru telescope out to flat mirror reflect back into eyepiece and
cut w/ razor blade to produce pattern of shadows. If primary is good, then secondary would need
help.
-Ed has book:
Telescopes, Eyepieces, and Astrography.
Asking JW about the Dall-Kirkham that he designed. http://www.willbell.com/TM/TelescopesEyepiecesAstrographs.html
-TimC showed TomT his handouts on Telescopes and described
the telescope grinding process, silicon carbide, aluminum oxide, cerium oxide,
and pitch materials and steps. TimC has
great booklet made by Joe Doyle on choosing telescopes.
-Captain Crutchfield Adair story of TimC childhood mentor he
never met to see telescopes, but Adair was in club when Tim joined later in
life.
-An email was sent to TimC from JavierR on July 21 “Tinkers
Festival” need for telescope mirror making demonstration table
"CALL FOR TINKERERS:
Greetings from the Santa Barbara
Museum of Natural History!
My name is Justin Canty, I am the
Community Education Manager for the Santa
Barbara Museum of Natural History and
the Ty Warner Sea Center.
On Sunday, July 21st, 2013 (10:00 AM – 4:00 PM) The Museum of
Natural History will host our first “Tinker Fest”. The inspiration for Tinker
Fest comes from the desire to inspire creativity & inventiveness in our
visitors. I am now accepting proposals from potential “Tinkerers”.
What is the
Tinker Fest? It is a festival
that will highlight the creative work of people & groups of all ages. The
festival allows for individuals or groups to showcase their projects; highlight the process of making things and
create an
interactive experience for participants. ..."
130305
130305 Telescope Workshop notes, March 5, 2013
Attendees: TomK, EdK, JerryW, TomT, DmitriiZ, TimC
TK- While waiting for 220grit for his big mirror polishing, he has 4.25” glass blank to make a solar dobsonian (for projection image for kids) grinding against another blank. TK asking JerryW about wedge angle on back to avoid extra 4-5% coming back on top of the front of the uncoated polished mirror. Sky &Telescope magazine may have info on making these. Or he might make it into a planetary scope. Jerry says power of scope could be up to 50-60X the primary inch size.
TC – showing three page “First Scope for Astronomy-What’s Best?” document. TK suggests sharing on Google Docs. Correction needed for refractor diagram. Doing more review, looking for glossary to define jargon. People start with eyes on constellations, then add binoculars. TT asked about apochromatic, and JW explained. TK suggested short refractors being handy for Firstt telescope. TC- side story, Nagler made TeleVue telescope to test his wide field eyepieces.
DZ,TK- say to TC, go to Google.com, log in, use docs.google.com. TC wants to make a poster for Astro Day of Tscope recommendation stuff. TC will email to TK. TK-going to science night at Vieja Valley and other with mirrors. Wants to help finish doc.
JW- When glass batches change, manufacturers generally come up with new name/type for their telescope due to the glass change.
Dmitrii- polishing 12.5” with Cerium Oxide solution. JW says it is a colloidal solution.
TT asking JW about focal length on Celestron SCT C8. Secondary mirror is convex, acting as a magnifier of perhaps 5X. Set up C8 Primary mirror at highest magnification, leave it there and use external fine focuser at 2” threaded end.
JW- Scope City (Thousand Oaks) out of business, do not use website, may lose money.
DZ- mentioned SBHackerSpace group looking for physical space to work in. so possible to combine with that group for permanent spot. Locker to hold mirror that is being worked on? Fyi: DZ- co-founder Eucalyptus.com cloud computing stuff. http://sbhackerspace.com/
Stellafane table for grinding mirrors. TC- 55gal drum with water does not go anywhere!
See http://stellafane.org/tm/atm/index.html
Attendees: TomK, EdK, JerryW, TomT, DmitriiZ, TimC
TK- While waiting for 220grit for his big mirror polishing, he has 4.25” glass blank to make a solar dobsonian (for projection image for kids) grinding against another blank. TK asking JerryW about wedge angle on back to avoid extra 4-5% coming back on top of the front of the uncoated polished mirror. Sky &Telescope magazine may have info on making these. Or he might make it into a planetary scope. Jerry says power of scope could be up to 50-60X the primary inch size.
TC – showing three page “First Scope for Astronomy-What’s Best?” document. TK suggests sharing on Google Docs. Correction needed for refractor diagram. Doing more review, looking for glossary to define jargon. People start with eyes on constellations, then add binoculars. TT asked about apochromatic, and JW explained. TK suggested short refractors being handy for Firstt telescope. TC- side story, Nagler made TeleVue telescope to test his wide field eyepieces.
DZ,TK- say to TC, go to Google.com, log in, use docs.google.com. TC wants to make a poster for Astro Day of Tscope recommendation stuff. TC will email to TK. TK-going to science night at Vieja Valley and other with mirrors. Wants to help finish doc.
TK- Find book from Willmann-Bell (www.willbell.com) about telescope issues. [lots of books on making telescopes, WOW!]
JW- Sky & Telescope has Ipad app for seeing how your telescope would see an object.
JW- Also app for predicting Jupiter's moons and red spot.http://www.skyandtelescope.com/community/skyblog/newsblog/Take-a-Tour-of-Jupiter-with-Our-Newest-App-182423791.html
TK- Orion Highlight plossel eyepiece with Orion ED80 for about $800, can see Mag 9 stuff, instead of Costco $200 stuff, so people can appreciate night sky.JW- Sky & Telescope has Ipad app for seeing how your telescope would see an object.
JW- Also app for predicting Jupiter's moons and red spot.http://www.skyandtelescope.com/community/skyblog/newsblog/Take-a-Tour-of-Jupiter-with-Our-Newest-App-182423791.html
JW- When glass batches change, manufacturers generally come up with new name/type for their telescope due to the glass change.
Dmitrii- polishing 12.5” with Cerium Oxide solution. JW says it is a colloidal solution.
TT asking JW about focal length on Celestron SCT C8. Secondary mirror is convex, acting as a magnifier of perhaps 5X. Set up C8 Primary mirror at highest magnification, leave it there and use external fine focuser at 2” threaded end.
JW- Scope City (Thousand Oaks) out of business, do not use website, may lose money.
DZ- mentioned SBHackerSpace group looking for physical space to work in. so possible to combine with that group for permanent spot. Locker to hold mirror that is being worked on? Fyi: DZ- co-founder Eucalyptus.com cloud computing stuff. http://sbhackerspace.com/
Stellafane table for grinding mirrors. TC- 55gal drum with water does not go anywhere!
See http://stellafane.org/tm/atm/index.html
JW- Russel Porter telescope donated to museum, stored somewhere. [base got lost, after it had been discovered at Bob Graves house.] http://www.sbau.org/newsletter/September2009.pdf
Photos: http://www.flickr.com/photos/27241501@N03/sets/72157632971487703/
Photos: http://www.flickr.com/photos/27241501@N03/sets/72157632971487703/
130212
SBAU Telescope Workshop, February 12, 2013
Attendees: TimC,
JerryW, TomKing, Ed Kalinsky, Dmitrii Zagorodnov, Ray, TomT
TK-JW helping check surface of TK quartz 12” mirror w/
spherometer and suggesting strokes to use in grinding w/ 120grit. 30Hrs spent so far; TK-continuing to grind at
meeting and achieved the desired spherical surface tonight and will move on to
220 grit. Mirror was bought preshaped.
He is using a ceramic plate made by TomW.
TimC setting up for Demitri Ronchi test. D at spherical
polishing stage.
-JK focusing and helping describe work needed.
Ray 8” Orion dobsonian newtonian w/ modified focuser
examined by TC/JW
-TC adjusting secondary, then primary to get red laser
placed in focuser centered
JW describe differences btw pyrex (borosilicate), quartz
(SiO2 crystal), plate glass for mirrors. Mt. Wilson mirror made from wind
bottles.
Photos from meeting:
Photos from meeting:
130115
SBAU Telescope Workshop, January, 15, 2013
attendees: tim c,
jerry w, tom t
-12.5” Cave mirror in cast cell brought in by Tim C.,
looking to make tube for it
Cave Optical Co. #M737961
F6, 75 1/8” F.L.
January 5, 1973
-discuss aspect ratio for tom t. 6:1, thickness of glass to diameter of
mirror.
Jerry talked about glass sag at thinner glass ratio (10:1)
-Book (and Sky&Telescope article) by Albert Highe
“Engineering, Design, and Construction of Portable Newtonian
Telescopes”
-advantage of laminated vaulted birch wood: better for lower coefficient of expansion
than aluminum
photos taken at meeting:
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