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Merope - engineering a low compromise compact 16" dob

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#226 mark cowan

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Posted 08 January 2019 - 05:22 PM

A 3 vane (6 wire) spider can't be made resistant to all vibration modes.  It takes 8 wires.  Ask me how I know...

 

See this adjustable design :

 

wires1.jpg

 

 

or for the best fixed version this one (stereo crossed pairs explain it best):

 

stereo crossed 1_.jpg

 

stereo crossed 2_.jpg

 

Or you might see it in rotation easier:  https://youtu.be/5bXHeE5P2KI

 

 

 

 

 

 

 

 


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#227 kb58

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Posted 08 January 2019 - 06:26 PM

Those pictures help a lot. Okay, consider it done, 4-point (8-point) it is!


Edited by kb58, 08 January 2019 - 06:50 PM.


#228 mark cowan

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Posted 08 January 2019 - 06:39 PM

Doesn't have to be 4 points.  The first one is 8 wires but not many points in common (just so you know):

 

wires3.jpg



#229 Oberon

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Posted 15 August 2019 - 05:33 PM

Observing note; Kookaburra doesn’t always sit in the old gum tree...

 

 

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#230 jtsenghas

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Posted 15 August 2019 - 05:40 PM

I hope he didn't christen your primary! 


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#231 Oberon

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Posted 15 August 2019 - 05:48 PM

Fortunately not, especially as it was freshly washed clean. I had just removed the cover for cool-down. 



#232 jtsenghas

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Posted 15 August 2019 - 06:09 PM

Good! After eating all those gum drops that may have been a problem! 

 

I've been meaning to ask, how thick is your 16" mirror?

 

I bought my 10" mirror before an 8" scope was finished, and bought my 12.5" before my 10" dob was finished. Now that my 12.5" is nearly finished I'm sitting on a decision whether or not to buy a certain refigured 16" f/4.5 that the owner is giving me first dibs on. I may hold out and wait until I can afford something faster and thinner, but I'm tempted to make another scope very much in this style. 


Edited by jtsenghas, 15 August 2019 - 06:10 PM.



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