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Need Help Designing Secondary Holder

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5 replies to this topic

#1 matt_astro_tx

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Posted 25 October 2021 - 09:11 AM

Good morning,

 

I am in the middle of building a 4" F/10 newtonian with my son.  You can see the progress of the build here.  As you can see I've built the tube out of wood in an octagonal shape.  We've already manufactured the mirror cell and last night we cut the focuser hole.  Now it's time to start thinking about the secondary.

 

Does anyone have a simple yet sturdy design for a DIY spider and secondary holder?  I don't have any metal fab skills or equipment but am a capable carpenter.

 

Edit: internal dimension of the tube is about 5" square (because its an octagon).

 

Thanks


Edited by matt_astro_tx, 25 October 2021 - 11:55 AM.


#2 rlw1138

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Posted 25 October 2021 - 12:35 PM

These are fantastic, and super-simple to make.....I've made several:

 

https://garyseronik....y-mirror-holder



#3 matt_astro_tx

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Posted 25 October 2021 - 01:06 PM

Thanks!  That'll probably be the route I take.  As luck would have it I just happen to have a metal ruler right here...



#4 Astrokhan

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Posted 25 October 2021 - 04:37 PM

This is what I made. Obviously based on Gary Seronik's design. Used a flexible metal strip and plastic bush/lugs to make the entire assembly.

 

https://astrokhan.wo...condary-holder/

 



#5 matt_astro_tx

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Posted 26 October 2021 - 02:11 PM

Where did you get the "bush" lugs that he references?



#6 MitchAlsup

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Posted 26 October 2021 - 04:14 PM

Does anyone have a simple yet sturdy design for a DIY spider and secondary holder?  I don't have any metal fab skills or equipment but am a capable carpenter.

SecondaryCD.jpg

 

secondaryCoG.jpg

 

secondarySmall01.JPG

There is no reason the aluminum could not be changed onto Baltic birch, plus you can glue the 45ยบ nose piece on (instead of screws).

 

Anyway, this secondary architecture has properties that make it inherently stiffer than the common secondary designs.

 

Mine can be collimated without tools, but this is just about getting the 4-40 screws to fit loosely in the threaded member (class 1 fit)




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