Help! - How can I fix my diagonal? Threadlock?

[Saturninus]

I have a William Optics 2" diagonal threaded for direct SCT attachment. The other night I was attaching it to my C8 in the dark and I over-tightened it. I wrenched it a bit too hard, felt a snap, and suddenly the diagonal was loose. The locking right was still tightened and the assembly was secure, but the diagonal rotated much too freely on the mount. I was able to get in a good hour of observing, but I was constantly paranoid that the diagonal would swing down and chuck my 2" eyepiece down onto the ground.

So afterwards I removed the diagonal and disassembled the whole thing. Nothing seemed cracked or broken, so I reassembled it and tightened the inner double threaded barrel (the piece that is secured by the locking ring onto the SCT - sorry I don't know the name of it), and re-attached it to the back of the SCT. The problem now is that whenever I turn the locking ring, it rotates the double-threaded inner barrel along with it, causing it to loosen as I try to thread the locking ring onto the SCT, or it tightens it really hard as I try turn the locking ring to unmount from the SCT, making the locking ring impossible to turn. 

I still can't figure out what I broke, but it must have been something that keeps the inner barrel from rotating (and thus tightening or loosening excessively) while I am turning the locking ring. How do I keep that inner barrel piece from rotating? Do I use threadlock? Was it glued before and that is what I wrenched loose?

Sorry if I am not describing it right - I know it sounds confusing, but I guessing many a noob has done this exact same thing. Can someone familiar with the pieces of a SCT threaded diagonal help me figure out how to get it back to the way it worked before I wrenched it? 

thanks in advance for any advice! I'll post a picture of the pieces if nobody knows what I am talking about

[M4lcs67]

Sorry for predicament. If nothing has been damaged from the ota side I would take this in a strange way as being the right time to get a Baader quicklock to fit on the back of your tube and the smooth nosepiece that came with your Williams diagonal will just replace the threaded barrel that attaches to the visual back. That is what I did with my rig and indeed many on SGL have done the same.

Originally I thought as you about using the threaded collar on my Williams 2" diagonal, but I was worried about the constant loosening and tightening of it all the time and the fact that it would wear the thread on the ota visual back eventually. That is why I went for the Quicklock. A very clever device.

[Saturninus]

The baader unit seems good, but expensive. Not sure if it would work with my diagonal since it has no nosepiece. <br />

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I guess i can just leave the diagonal on semi-permanent. I only wanted to take it off for transport or prime focus photography. But i sense that if i just understood the parts more, it would be an easy fix<br />

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Sent from my MB855 using Tapatalk 2<br />

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[JamesF]

A picture may well help here I think.

James

[Tinker1947]

As James typed a Photo will help.....something like this ...

[Saturninus]

Yes I should have posted an image to begin with but I was at work so I couldn't. But here it is. This first picture shows the OTA side of the diagonal disassembled. The piece in the middle, that is what I was referring to as the inner barrel. The piece on the right is the locking ring. The inner barrel has a male thread that screws into the diagonal. But first, it goes through the locking ring, and the locking ring has the female thread that accepts the male thread of the SCT.

So the problem is that now whenever I turn the locking ring to screw it onto the SCT, the friction turns the inner barrel also. And since the inner barrel is threaded into the diagonal, whenever it is turned, it either over tightens, such that locking ring is compressed against the diagonal so hard that it cannot turn either, or turning the locking ring the other way, the inner barrel is turned also and unscrews from the diagonal, such that the assembly is too loose.

So when I turn the locking ring clockwise to secure it onto the SCT, it rotates the threaded inner barrel counterclockwise in the diagonal and unscrews it. Conversely, when I turn the locking ring counterclockwise to unmount it from the SCT, it rotates that inner barrel piece clockwise in the diagonal, screwing it into the diagonal so tightly that it jams the locking ring.

If I could only get the inner barrel piece to not rotate one way or another when the locking ring is turned, I could mount and unmount it easily. Is it supposed to be secured somehow?

Thanks to anyone who can figure out what I'm trying to say!

[ChrisLX200]

A dab of thread-lock on the threads of the insert will hold it - Loctite retaining compound would be my choice (Locitite 638)

ChrisH

[NGC 1502]

This may be irrelevant, however -

Are there any grub screws that secure the inner barrel part to stop it from turning ?

Can't quite see from the pics, but a careful inspection might show something like that.

If no grub screws, perhaps loctite, as already mentioned.

Hope you sort it, Ed.

[coulthamst]

Was there perhaps a now missing spacer washer between the inner barrel and th "step"  noticeable inside the main body of the diagonal?

[Tinker1947]

It would seem the middle piece in the first photo needs to be tightened enough that the right hand ring turns but doesn't have any play on it, if there are no allen screws on the main body to hold the middle ring then as ChrisH typed get some Loctite but make sure its the right stuff the number type 638, don't use normal of the shelf glue in the supermarkets there not any good, it comes to getting a replacement i can recommend Baader Click-Locks.....

[Zakalwe]

If you take the carbon fibre side cover off then i am pretty sure that there are a couple of locking grub screws underneath. Thats how my WO diagonal works, but they have changed the design.

[Zakalwe]

If you take the carbon fibre side cover off then i am pretty sure that there are a couple of locking grub screws underneath. Thats how my WO diagonal works, but they have changed the design.

Sorry, can't edit the post but I meant to say "but they may have changed the design"

[Saturninus]

Thanks for all the help all. I didn't see any grub screws to hold the inner barrel in place, but I didn't think to look from inside the diagonal with the sides removed. I'll take a look again when I get home from work. That might have been what broke free when I over-tightened it, but I don't remember seeing any holes or hearing any loose pieces rattle around. If all else fails, I will use thread lock 

There is a washer/plastic bushing between the inner barrel and the diagonal, but it survived intact and I placed it back exactly where i found it. 

[coulthamst]

Perhaps the plastic bushing you describe has become over compressed and is now allowing the inner barrel to tighten down to a point where it touches the locking ring. You could try to get a washer or thicker bushing, failing which a ring of hefty copper wire might help, provided it was accurately made to the correct diameter and the ends soldered together.