Author Topic: Who has ground their own mirrors and how many?  (Read 209 times)

neulosali

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Who has ground their own mirrors and how many?
« on: December 30, 2017, 02:46:54 AM »
I have always been curious as to how many ATMers have ground their own mirrors?
What did you grind?

I'll start. I've ground 2 and 1/2.

1st:  classic 6" f/8 from Edmunds kit back in high school (late 60s).  Don't know the figure but, performed well.
2nd:  4.15" f/4.8 for widefield viewing. Came out about lambda/6 ... pretty good optic.

last:  started a 16" f/5 project. Ground it out through fine Al-O, ready for polishing.  Major life events cancelled that project.



hluhsubshoona

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Re: Who has ground their own mirrors and how many?
« Reply #1 on: December 30, 2017, 05:27:11 PM »
Done about 60 mirrors, including refigures, from 4" to 20".

Dave

pregdefciato

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Re: Who has ground their own mirrors and how many?
« Reply #2 on: December 31, 2017, 03:34:11 PM »
Ground, polished and figured several ranging in size from 4.25" to 12.5" in the sixties. Still have a 16" full thickness ULE f/6 polished mirror that's yet to receive its final figure. Doubt I'll ever get around to finishing and mounting it. Too many other projects on my bucket list.

housletica

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Re: Who has ground their own mirrors and how many?
« Reply #3 on: January 09, 2018, 03:44:33 AM »
6" f9
6" f4.5
10" f6.5
10" f5 refigure
16" f4

exvermabo

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Re: Who has ground their own mirrors and how many?
« Reply #4 on: January 11, 2018, 08:37:31 AM »
none
nope
nada
not one
who would ever do such a thing?

Tom Doyle

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Re: Who has ground their own mirrors and how many?
« Reply #5 on: January 11, 2018, 09:14:12 AM »
Me neither.

grountentaybrig

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Re: Who has ground their own mirrors and how many?
« Reply #6 on: January 11, 2018, 04:53:28 PM »
Have made:
4" f/10
6" f/8
8" f/5
10" f/6.5
12.5" f/5.2
20" f/3.9

Upcoming projects:
two 8" f/5 (fall 2016)
12.5" f/3 (2017)
20" f/3.7 (2018) goals:
shorten current f.l. to 68" eyepiece height (same 4" diagonal);
grind out many surface scratches generated during first pass
re-parabolize to much higher quality
4.5" f/15 mak (2019)

bronedproudem

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Re: Who has ground their own mirrors and how many?
« Reply #7 on: January 12, 2018, 08:58:23 AM »
4.5" f/3.5
6" f/4
6" f/7
8" f/2.9
8" f/3.5
12.5" f/4.2
20" f/3
Soon to start a 20" f/4

Recently finished an 8" Houghton-Cassegrain objective plus 4" secondary and 3" field flattener lenses. (I plan to post some details on that project once the weather cooperates for a proper first light.) Almost done with a 3.5" f/7 achromat. And I'm sort of in blank hording mode now.... So much glass, so little time.

Scott

Jerry Gilbert

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Re: Who has ground their own mirrors and how many?
« Reply #8 on: January 13, 2018, 04:33:15 AM »
I've only done a few mirrors: an 8", F/6.7 (Pyrex) and an 8", F/5 (Cervit) primaries. I also made the flat fold mirror for the F/5 and a Cassegrain secondary (both fused silca) to make a F/16 EFL scope. I had a lot of fun testing all this stuff with a scatterplate interferometer in grad school. I used the F/6.7 8" Newtonian for years but I never got around to putting the Newt/Cass together. I inherited the optics for a 12.5", F/5-F/15 Newt/Cass and it seemed like a more interesting project so I built that instead. All of that stuff happened a long time ago before I reached a point where I'd rather use it than build it.  Now I just buy what I need. I suppose that one of these days I should try to find a good home for all of the "spare" parts and telescopes that I have lying around. 

John

Anthony Graham

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Re: Who has ground their own mirrors and how many?
« Reply #9 on: January 20, 2018, 02:45:24 PM »
6" f/8 from a willman bell kit. badly damaged some time later when the duct tape holding the secondary strut in place dried out and it fell edge down onto the primary. sold the whole telescope.

prehconbubun

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Re: Who has ground their own mirrors and how many?
« Reply #10 on: January 22, 2018, 09:33:36 PM »
I stopped counting when I hit 100. I also ground 16 refractor objectives; frankly, I found these more fun to make and test.
ed

Cory Bass

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Re: Who has ground their own mirrors and how many?
« Reply #11 on: January 22, 2018, 10:31:31 PM »
Quote
none
nope
nada
not one
who would ever do such a thing?

 


After doing two (10" f/9, 10" f/5), I kind of realized it was more time efficient for me buy from a premium maker which allows me to spend my time on the mechanicals.

It was good experience, and gives me appreciation for the challenges an optician faces.

Maybe after I retire ... but for now not enough hours in the day.

Abdullahi Archer

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Re: Who has ground their own mirrors and how many?
« Reply #12 on: January 22, 2018, 11:19:33 PM »
it can get Juicy...

stancacoho

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Re: Who has ground their own mirrors and how many?
« Reply #13 on: January 25, 2018, 07:05:38 PM »
about 20 primarys, 4-12 inches, a couple secondaries, a few small lenses.

frenafverbi

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Re: Who has ground their own mirrors and how many?
« Reply #14 on: February 03, 2018, 12:52:07 PM »
Back in the 1960s-70s:
Several 4", 8.75", 12" & 16" mirrors
Several 8.75" optical flats.
A 5" f/15 and several smaller achromats.
Several 60° dense flint prisms.
And lots of simple lenses.
Had I worked by hand instead of on my own machine:
I might have made many more.
And smoked far less.