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Considering a 1 metre Optiques Fullum folded newtonian. Please debate pros/cons.

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#76 Bob4BVM

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Posted 20 March 2021 - 01:10 PM

Yes I would love to do that. I'm limited by practicality constraints of time and capability of doing it myself, and I've gone searching and can't find any local expertise to contract out to do it. Everyone who's got one that I've contacted did it themselves, and it took far longer than they'd hoped. I plan to be up and running by the start of next year.

Good grief, ROR's are NOT complicated !

If you can't find a builder who can do it from a good set of plans, you should keep looking til you find one with half a brain :)

Also, you might consider a roll-off building on ground-level rails, like Mike Clements did for his 70" in Utah. You could easily fab such from a steel shipping container which would be very secure and completely fire-proof. Roll it back and you are observing, no moving the scope at all...

CS

Bob


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#77 Ittaku

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Posted 20 March 2021 - 04:15 PM

Good grief, ROR's are NOT complicated !

If you can't find a builder who can do it from a good set of plans, you should keep looking til you find one with half a brain smile.gif

Also, you might consider a roll-off building on ground-level rails, like Mike Clements did for his 70" in Utah. You could easily fab such from a steel shipping container which would be very secure and completely fire-proof. Roll it back and you are observing, no moving the scope at all...

You know, you're absolutely right! Will investigate shipping containers... though they're only 8 feet wide and the scope won't fit in that.


Edited by Ittaku, 20 March 2021 - 04:19 PM.

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#78 John_K

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Posted 22 March 2021 - 07:57 AM

Congrats! I think that would make it the largest amateur instrument in Oz! Great to have it here in Vic. 


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#79 Bob4BVM

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Posted 22 March 2021 - 02:24 PM

You know, you're absolutely right! Will investigate shipping containers... though they're only 8 feet wide and the scope won't fit in that.

The 50" scope is over 96" wide ?!!



#80 Ittaku

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Posted 22 March 2021 - 03:54 PM

The 50" scope is over 96" wide ?!!

Whoa, serious brain fart on my part there. Blame my metric brain. Will investigate further, thanks.



#81 Ittaku

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Posted 28 March 2021 - 03:54 AM

328 Columns that will make the core of the Techno Fusion mirror
164622772 125225659565798 7221247906184574681 N
 
3x50 inch diameter Boro Discs that will be part of the fusing process
166164593 301367508089189 7696211157234832145 N

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#82 Ittaku

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Posted 17 April 2021 - 12:49 AM

The top plates are in the Kiln for fusion, this will take 2-3 days for this initial stage of the blank creation to happen.
Then they will add in the columns and after will fuse on the back plate and obtain the blank at its pre-slumping stage.

Below before it went into the Kiln.

 

170669386 1068155897003110 603976174413790405 N
173594174 304968107709843 1155110724954795798 N
172381714 3578345005724723 5847555594069206791 N

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#83 a__l

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Posted 17 April 2021 - 05:29 AM

It will be interesting to look at the diffraction of stars. How these columns will look.



#84 Tyson M

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Posted 18 April 2021 - 04:41 AM

It will be interesting to look at the diffraction of stars. How these columns will look.

The top part of the mirror is reflective? So the columns dont impact star shapes to causes diffraction.

 

Unless I am missing something, the only noticeable effect is much faster cool down of this very large mirror.


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#85 Ittaku

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Posted 18 April 2021 - 05:10 AM

The top part of the mirror is reflective? So the columns dont impact star shapes to causes diffraction.

 

Unless I am missing something, the only noticeable effect is much faster cool down of this very large mirror.

That's correct, it's just the technofusion design which makes it much lighter to have two pieces of borosilicate with the columns between them for enough stability yet to cool down much faster, otherwise it would take many hours to cool if it were one solid piece thick enough to support its size without bending under its own weight.


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#86 Arctic eye

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Posted 18 April 2021 - 09:02 AM

It will be interesting to look at the diffraction of stars. How these columns will look.

 

The top part of the mirror is reflective? So the columns dont impact star shapes to causes diffraction.

 

Unless I am missing something, the only noticeable effect is much faster cool down of this very large mirror.

 

I think a__I is referring to print-through. Like in my SW20" goto dob, where the underlying mirror structure was directly visible in the star test. Too much force during the figuring, and the area between the ribs bends down and less material is removed there compared to the places where the ribs are, so the rib structure gets copied to the optical surface or something like that. But they sure know how to deal this in Fullum. My SW20" dob was like this:

 

startest2.jpg?img=full


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#87 Tyson M

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Posted 18 April 2021 - 11:47 PM

I think a__I is referring to print-through. Like in my SW20" goto dob, where the underlying mirror structure was directly visible in the star test. Too much force during the figuring, and the area between the ribs bends down and less material is removed there compared to the places where the ribs are, so the rib structure gets copied to the optical surface or something like that. But they sure know how to deal this in Fullum. My SW20" dob was like this:

 

startest2.jpg?img=full

Oh I see.  Thanks for clarifying.

 

Well, I guess I should state the obvious that Skywatcher and Normand Fullum are very different makers occupying their own niche. 

 

I never heard of this happening with HO mirrors either though, which are attractively priced, good quality and more comparably priced to Skywatcher.


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#88 a__l

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Posted 19 April 2021 - 02:31 AM

But they sure know how to deal this in Fullum. 

Tell us in more detail.



#89 Arctic eye

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Posted 19 April 2021 - 03:38 PM

Tell us in more detail.

I meant to say: But they surely know how to deal this in Fullum. I have no knowledge of Fullum, sorry...


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#90 Ittaku

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Posted 25 April 2021 - 06:29 PM

Composite mirror construction in process.

 

177924921 867784480804512 6455515006261402371 N
178808086 2942956885993978 8124940767337076586 N

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