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The How to Thread

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#76 reverse_syzygy

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Posted 09 May 2024 - 09:21 PM

 

Here is another (improved?) way to attach the homebrew drain coupling 1.25" adapter to the draw tube of an old RAO telescope with a .925" visual back. The way I used to attch the adapter was to remove the .925" VB, slide the adapter over the drawtube, then tighten the nut and plastic collar on the adapter.

 

Here is the new way.

  1.  attached to the draw tube by the VB threads: 
     

... ...

...

If you want you could cut off the body of the VB after the taper behind the knurled collar

OK, I'm maybe out of my element here - since I still need to buy that coupling part - but the new way, I'm not sure if that's an improvement.

My assumption was that you want an entirely new Visual back or coupler like the original so that you get the benefit of the wider optical path.

If you're just fitting the coupler over the 0.965" VB, aren't you still optically limited by the smaller diameter?

 

I was under the impression that a simple 0.965-to-1.25 adapter vignettes in 1.25" EPs.   That it doesn't gain you anything beyond using more modern glass.   I'm not sure how this "new" way is really anything more than that, with added complexity.

 

What am I missing here?

 

And NO cutting of the old VB for me.  I want something completely reversible



#77 Senex Bibax

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Posted 10 May 2024 - 08:31 AM

OK, I'm maybe out of my element here - since I still need to buy that coupling part - but the new way, I'm not sure if that's an improvement.

My assumption was that you want an entirely new Visual back or coupler like the original so that you get the benefit of the wider optical path.

If you're just fitting the coupler over the 0.965" VB, aren't you still optically limited by the smaller diameter?

 

I was under the impression that a simple 0.965-to-1.25 adapter vignettes in 1.25" EPs.   That it doesn't gain you anything beyond using more modern glass.   I'm not sure how this "new" way is really anything more than that, with added complexity.

 

What am I missing here?

 

And NO cutting of the old VB for me.  I want something completely reversible

I'm not sure either. I meant better in that the coupling is more securely attached to the draw tube. I have wondered about the restriction of the light path due to the I.D. of the original VB, but I haven't yet had an opportunity to verify with real observations. Tonight is supposed to be clear, hopefully i will be able to confirm or refute.

 

As far as cutting the original VB, I happen to have a spare RAO .925" screw-in VB, but I'd still rather not cut it.


Edited by Senex Bibax, 10 May 2024 - 08:32 AM.

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#78 reverse_syzygy

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Posted 11 May 2024 - 10:01 AM

I'm not sure either. I meant better in that the coupling is more securely attached to the draw tube. I have wondered about the restriction of the light path due to the I.D. of the original VB, but I haven't yet had an opportunity to verify with real observations. Tonight is supposed to be clear, hopefully i will be able to confirm or refute.

 

As far as cutting the original VB, I happen to have a spare RAO .925" screw-in VB, but I'd still rather not cut it.

Right on.  Hope to hear how it goes between the two methods, with/without old v.b. - From everything I gathered in the past trying to adapt to 1.25" it's the old 0.965 back that obscures light.  

I'm pretty sure this is the very reason why I never bothered to find a 0.965-to-1.25 hybrid diagonal.



#79 Mickeyemer

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Posted 09 June 2024 - 01:40 PM

You know me, I LOVE Coulter Odyssey telescopes.

They are fast at f/4.5 and also because they have a 1.25" focuser so you cant see

the whole primary making collimation a little more difficult.

Because of this fast speed collimation is critical.

I suppose these days f/4.5 is more the norm.

To get to the point of my post, I like to center mark these fast mirrors so I can use a

3-hole binder hole reinforcement ring on center and a Barlowed laser.

Draw your mirror on a piece of paper, fold into quarters, snip the tip off of the

folded pie shaped piece, unfold and carefully place on the mirror, use a sharpie thru

your snipped hole to mark the center of the mirror. Add the reinforcement ring.

If you use a compass like in my photo you will have the needed center and no folding

is neccessary.

Read the article in the Jan 2003 Sky & Telescope for barlow laser collimation by Nils Olof Carlin.

 

Robert

 

attachicon.gif post-50896-0-99491700-1540508707.jpg

Link to said article, DS-10 is similar to coulter, needs to be done similarly.

https://www.tomhole....0/12/blaser.pdf


Edited by Mickeyemer, 09 June 2024 - 01:43 PM.

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#80 Senex Bibax

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Posted 21 June 2024 - 07:51 AM

Here's my latest attempt at a cheap and easy 1.25" VB adapter for old RAO .925" focusers with the long draw tube. This might be the simplest yet.

 

A few months ago I made an adapter using a short slip joint plumbing coupler. It works after a fashion but adds close to 10 cm / 3" to the light path. 

RAOAdapter1

RAOAdapter4
 
My latest adapter is almost half that length, and the components are even cheaper. I made it out of a short 1" plastic electrical conduit coupling and an old bicycle 1 3/8" inner tube. The coupling is 2" / 5 cm long, and has internal threads on one end. Although nominally for 1" conduit, the i.d. is actually slightly more than 1.25".  There are similar couplings that are straight through inside, but the ones with partial threading have a convenient lip half way through the inside. I simply cut two pieces  from the inner tube, slightly shorter than the coupling, inserted them into each end and folded them back over the outside.
 
I added a short piece of inner tube around the middle of the original screw-in VB, which gave it a snug push-in fit in the threaded end of the coupling. The coupling could now be screwed into the draw tube using the threads of the .925" VB. The second sleeve of inner tube in the unthreaded end of the coupling gives a nice push fit for the nosepiece of a 1.25" diagonal, holding it securely enough but easy to remove.
 
The original VB and the diagonal meet at the internal lip halfway through the coupling, so it is just the right length.
 
The final touch is a shot of flat black primer on the inside for good measure. Total cost - $2.99.
 
RAOAdapterV2 4
RAOAdapterV2 3
RAOAdapterV2 2
RAOAdapterV2 1

 


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#81 Cavs56

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Posted 02 July 2024 - 11:02 AM

I have just acquired a Meade 826. I need to remove the lens cell to clean the mirror. I removed the three screws that hold the cell in. It doesn’t budge. Any tips?

#82 Garyth64

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Posted 02 July 2024 - 12:27 PM

I have just acquired a Meade 826. I need to remove the lens cell to clean the mirror. I removed the three screws that hold the cell in. It doesn’t budge. Any tips?

It's probably never been removed before so it is just stuck to the surface of the tube.  



#83 Cavs56

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Posted 02 July 2024 - 01:12 PM

Thanks Gary yes just stuck. I don’t think it was ever out. I am going to post pictures in another thread. I probably drove right past you on the way to pick it up. I’m south of Dayton and picked it up at the 32 mile marker on 75 in Michigan.
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#84 Garyth64

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Posted 02 July 2024 - 02:35 PM

Yep, I've very close to 75 and Northline.

 

Heck, I could have loaded you up with some scopes.  I have some excellent scopes that I plan on thinning out.  smile.gif

 

I don't want to ship them.


Edited by Garyth64, 02 July 2024 - 02:35 PM.


#85 Cavs56

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Posted 02 July 2024 - 03:30 PM

At this point I think we would have to trade or my wife might have me committed.

#86 deSitter

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Posted 02 July 2024 - 04:40 PM

Thanks Gary yes just stuck. I don’t think it was ever out. I am going to post pictures in another thread. I probably drove right past you on the way to pick it up. I’m south of Dayton and picked it up at the 32 mile marker on 75 in Michigan.

Persuade it - paint stick held against the cell, gentle tap with a persuader (also known as a hammer).

 

-drl



#87 Cavs56

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Posted 02 July 2024 - 06:14 PM

I was scared to death to hit it. So many times I’m like a bull in a china shop and mess something up.

#88 AstroKerr

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Posted 05 July 2024 - 03:46 PM

So, has fear perished you or have you tapped? 



#89 Cavs56

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Posted 05 July 2024 - 09:24 PM

I guess I yanked hard enough it let go.
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#90 AstroKerr

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Posted 05 July 2024 - 10:14 PM

Well, that is a win waytogo.gif



#91 Kasmos

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Posted 12 July 2024 - 03:14 PM

More of a Where to get, then a How to.

 

If you have a box that has a missing a metal corner protector or just want to add some,

The most acceptable and closest to the old ones I could find were on Ebay.

 

Corner-pack.jpg

The best deal I found was under $10 for (16) stainless steel with screws (enough for two boxes).

https://www.ebay.com/itm/395289113249

 

Corner-At.jpg

How they'll look on a box

 

Corner-Sears.jpg

They are pretty close to the ones on Sears and other Towas.

I also think it's big enough to cover the two old holes.

 

Corner-Cres.jpg

My Crescent (Old Towa) and Swift both have this style and each are missing a couple.

My plan it to rearrange them so the replacements go on the bottom back side.

I thought I might make some cuts out with a Dremel to emulate the originals

But since the shape is different I'm not sure I can make a suitible looking cutout.

I'd draw something up first if I go this route.

 

Corners-Short.jpg

On these two boxes I'll put all of the originals on one box and the other will probably get all new ones.

There might be enough space below the screw hole on the new ones to cut them down to this shape.


Edited by Kasmos, 12 July 2024 - 03:41 PM.

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#92 deSitter

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Posted 13 July 2024 - 11:35 AM

Excellent find!

 

Could you outline your technique for filling in old screw holes?

 

-drl


Edited by deSitter, 13 July 2024 - 11:47 AM.


#93 Kasmos

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Posted 13 July 2024 - 02:34 PM

Excellent find!

 

Could you outline your technique for filling in old screw holes?

 

-drl

It depends on the size of the hole and the situation.

The last one I did I used my favorite way, a glued in toothpick.

I usually test fit it's depth, mark it and cut it, or score it, glue it in or snap it off it's been scored.

If it sticks up a little you can usually mash it down and the top will sort of splinter and fill.

Sometimes it works so well no putty is needed.

Toothpick.jpg

This was on a Unitron Tripod Box where I needed to relocate a nail that was too close to the edge of the side piece and split it.

I just wanted to fill the hole, and since the box is rough I'll probably leave it be.


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