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Bringing set screw TV 2" Everbrites back to life

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#1 aa6ww

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Posted 23 July 2019 - 02:46 AM

I have a few 2" TV diagonals from the past which were around before the brass compression rings were the norm. One is an Everbrite, the other is an Enhanced 2" diagonal, both are excellent diagonals.

I thought about just selling them both, and buying a more modern TV Everbrite with the brass compression ring. 

 

Then I thought, why dont I just remove the set screw, then drill and tap at least one more hole in the diagonals, then use nylon screws instead of  chrome set screws. I havent checked the size of the current set screw, but maybe its got 8/32nd threads, or even 10/32nd threads. The larger diameter the better.

 

Ive done this numerous times, with many parts requiring a set screw, basically just modernizering them with Nylon screws to prevent scratches.

 

Has anyone ever tried this with a quality 2" diagonal like these Televue diagonals I have, which just uses set screws?

 

I dont care for these older set screw diagonals because I dont want my 100 deg eyepieces scratched up.

 

Thanks in advanced for any comments. 

 

...Ralph



#2 Jon Isaacs

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Posted 23 July 2019 - 04:31 AM

I have a few 2" TV diagonals from the past which were around before the brass compression rings were the norm. One is an Everbrite, the other is an Enhanced 2" diagonal, both are excellent diagonals.

I thought about just selling them both, and buying a more modern TV Everbrite with the brass compression ring. 

 

Then I thought, why dont I just remove the set screw, then drill and tap at least one more hole in the diagonals, then use nylon screws instead of  chrome set screws. I havent checked the size of the current set screw, but maybe its got 8/32nd threads, or even 10/32nd threads. The larger diameter the better.

 

Ive done this numerous times, with many parts requiring a set screw, basically just modernizering them with Nylon screws to prevent scratches.

 

Has anyone ever tried this with a quality 2" diagonal like these Televue diagonals I have, which just uses set screws?

 

I dont care for these older set screw diagonals because I dont want my 100 deg eyepieces scratched up.

 

Thanks in advanced for any comments. 

 

...Ralph

 

Ralph:

 

I have 5 Everbrite's, only one of them has compression rings.   The standard screws for these are aluminum 10-32's.   Aluminum shouldn't mar the your 100 degree eyepieces.  

 

I just use them.  A single setscrew is plenty.  If the threads on the aluminum screw wear out, I replace them with nylon.

 

Jon



#3 mountman

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Posted 23 July 2019 - 08:22 AM

I agree with Jon here but prefer brass.  Simply sand the tips smooth if they have a manufacturing burr. 



#4 mrowlands

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Posted 23 July 2019 - 08:31 AM

I have a 2 inch focuser that has 1 nylon set screw, and it would not keep a 2 inch diagonal with a Nagler 31 from rotating when using various angles on an equatorial mount.  The end of the nylon screw was just crudely cut off.  I shaped it to a sort-of ball, and now it holds, but barely.  Obviously 2 screws at 90 degrees would be much better. 

 

Unfortunately, on my focuser, making a second hole would prevent the focuser from fully retracting, so I'm living with it as is.

 

Mike R.



#5 aa6ww

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Posted 23 July 2019 - 10:47 AM

All great advice from everyone, thank you.

I'm liking the brass thumb screw option. I think I may go with 10-32 brass thumbscrew's and drill and tap a second hole since I always prefer two vs one screw.

...Ralph

#6 Starman1

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Posted 23 July 2019 - 04:00 PM

Brass and aluminum screws WILL leave marks on the eyepiece.

If the goal is no marks, don't get either material.

I would drill and tap another hole 120° around the perimeter from the first.

Make both holes larger if you can.  Tap out to whatever larger diameter works and get 2 nylon screws.

P.S. even nylon screws, over time, will leave marks, but the marks will be small shiny spots, not scratches.


Edited by Starman1, 23 July 2019 - 04:01 PM.

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#7 havasman

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Posted 23 July 2019 - 04:17 PM

I've removed the "brass" compression rings from everything I regularly use and replaced the screws with nylon screws. I'll never have another problem with undercuts or junctions on TV eyepieces with that 2" extension tube getting stuck on the edge of the ring as I have in the past. If your focuser has good cylindricity in the mating bore and your eyepieces' major o.d. is also cylindrical then 60 to 90 degree screw offset angles should provide best mating stability and force of the two surfaces with less torque required on the screw.

IME compression rings are incrementally less bothersome than undercuts )and tapers like ES uses) but when they go wrong they are a much bigger problem.

The interface I like best is a good collet type retainer like the 2" one on the APM prism diagonal. I understand they also can present problems but they're the best for me with my gear.


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#8 aa6ww

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Posted 30 July 2019 - 11:37 AM

Thanks for all the advice on how I could upgrade my older TV Everbrite with one set screw to something that wont scratch up my new expensive eyepieces. I ended up purchasing some 1/4-20 x 1/2" nylon thumb screws from Scopestuff and tapped two larger holes in my Everbrite diagonal. I also sanded the length of the screw shorter then 1/2"
Now everything is great, no more chance of scratching my nice big eyepieces, and the dual screws keeps everything secure.

...Ralph in Sac

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#9 vkhastro1

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Posted 30 July 2019 - 12:58 PM

I done exactly the same thing.

I simply beveled the end of the existing metal set screw until it was easily removed.

I replaced it with a same size nylon thumb screw.

 

Also drilled and tapped a 2nd similar sized hole for an nylon thumb screw.

Old is “new” again !




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