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38" and 44" plate glass - usable?

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15 replies to this topic

#1 opticsguy

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Posted 13 August 2017 - 10:10 AM

Many many years ago when ATM's were working with, what was then, thin mirror technology, I was also exploring some possibilities. I did successfully slump a 26" x 1"  plate glass and was looking on to other possibilities. I acquired some large sheets and cut both a 38" x 1" and a 44" x 1.25" . Next step was building a large kiln for slumping but as what often happens in life, career, marriage and etc gets in the way along with other hobbies and etc.  I still have these blanks and obviously will never use them as intended.  As an aside, I did make up a very nice 54 point flotation for the 38".  Looked like it would have worked excellently.

 

So, my question, should I be making some nice glass topped tables or is there any possibilities of truly thinly slumped blanks for use in a scope?  Too heavy to throw at a hydrant...............


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#2 bvillebob

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Posted 13 August 2017 - 10:56 AM

Down here in the Eugene area there's a group of people working on these.  I saw Mel Bartel's mirror he's working on now, I believe it's about 25" x 0.5" slumped meniscus mirror.

 

He's probably your best resource to touch base with and can point you towards other resources I'm sure, his email is readily found via Google.



#3 Pinbout

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Posted 13 August 2017 - 11:21 AM

Cut them up to smaller blanks and sell them


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#4 opticsguy

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Posted 13 August 2017 - 01:03 PM

I was thinking to haul both blanks and the 54 point suspension to OSP if someone can really use them.  Otherwise it is a big big package to haul with no results. 



#5 rwiederrich

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Posted 13 August 2017 - 07:52 PM

Yeah..when I had my mirror making shop I was working on a 24"......I never got to it but the blank is still in my shop and I'm headed to Mark Cowen's place down in Salem the weekend of the Eclipse and I'm dropping off lots of other blanks and dodads.

 

You might find someone who would tackle sucha project at the OSP....good luck.

 

Rob



#6 Jack Day

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Posted 14 August 2017 - 12:42 AM

Kreig,

 

Cut the 44" down to 24", then slump that to f/3....  I think you know where to take it from there.  If not just watch some late night TV, you never know perhaps "Elvira" could inspire you!  ;-)



#7 opticsguy

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Posted 14 August 2017 - 08:25 AM

Jack, you think I can get  5 - 24" blanks outta the 44"?

If I cut a 24" outta the 38" can I make a Cassegrain or a Maksutov??



#8 Dave O

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Posted 14 August 2017 - 10:29 AM

Jack, you think I can get  5 - 24" blanks outta the 44"?

https://en.wikipedia...ing_in_a_circle

 

But, the answer is no ... you can't even cut two 24" blanks out of a 44" disk ...


Edited by Dave O, 14 August 2017 - 10:33 AM.


#9 Pinbout

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Posted 14 August 2017 - 01:14 PM

44in disc.jpg


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#10 mark cowan

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Posted 14 August 2017 - 03:45 PM

Nice.



#11 opticsguy

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Posted 14 August 2017 - 11:14 PM

Quote:  You think I can get  5 - 24" blanks outta the 44"?

 

Just a little joke???  lol.gif



#12 mark cowan

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Posted 19 August 2017 - 08:00 PM

Yeah..when I had my mirror making shop I was working on a 24"......I never got to it but the blank is still in my shop and I'm headed to Mark Cowen's place down in Salem the weekend of the Eclipse and I'm dropping off lots of other blanks and dodads.
 
You might find someone who would tackle sucha project at the OSP....good luck.
 
Rob

Woohoo!  
 
Had a great chat with Rob and his son today, shop tour and all that - and look what he left me!  

IMG_0594.JPG


IMG_0595.JPG

IMG_0598.JPG
 
23" plate blank, 17" plate fully polished out f/3 or so, 12" f/3 or so diitto, a couple 8" plate blanks, and this large collection (6!) pieces of 10.25"x1.25" vintage Pyrex from who-knows-what secret project, with numbers on the edge and notches of varying depth for making your own high voltage insulator, or something...  The latter will probably make into a series of fast 10" mirrors later in the year.  
 
The 8" are too small for me but PM me if you'd like one for postage.  Ditto for the small pitch lap tool.  
 
Rob, thanks again! waytogo.gif

Edited by mark cowan, 19 August 2017 - 08:14 PM.

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#13 mark cowan

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Posted 20 August 2017 - 10:28 PM

After thinking it over I'll likely generate the 10.5" blanks and offer them up for sale.  Checking them for strain first.  Still no real idea what these were from or for - there are #s on the sides engraved into the glass, up to double digits.  Look like very nice Pyrex, blancharded both sides.


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#14 rwiederrich

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Posted 20 August 2017 - 11:14 PM

Mark..it was a pleasure to visit you and your wife.  You definitely sure have the shop and test equipment.  Reminds me of my old shop.  I'm so glad you can use the blanks...they were simply wasting away

 

When you can get around to it..throw some images up of the 18"...I never got to see it figured since I shut down ops.  The 13" was in the same batch so it too never got to be evaluated..  They both were in the beginning stages of figuring.

 

Again..thanks for the fine welcome and tour....I'm blessed.

 

Rob


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#15 mark cowan

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Posted 20 August 2017 - 11:47 PM

hen you can get around to it..throw some images up of the 18"...I never got to see it figured since I shut down ops.  The 13" was in the same batch so it too never got to be evaluated..  They both were in the beginning stages of figuring.

 

Will do, planning to put them on the bench early this week.  Got this "eclipse" thing to have a look at first, though.  :lol:

 

Those two mirrors look pretty nice.  Hoping the 18 (or 17" I think) is about ready to go.  Around f/3 as we checked the sun spot on it.

 

Was fun, good to meet you finally!



#16 rwiederrich

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Posted 21 August 2017 - 01:03 AM

Awesome......I'm pumped too.

 

Now we can relate......on a different level.  Thanks for the peek into your plans...I'm very impressed.

 

Rob(I used my homemade binos tonight for the first time on Saturn..my homemade scope works so good with them)




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