Diagonal Slippage

[NightCal]

I've currently got a stock Meade 1.25" diagonal in the rear cell of my 8" LX200 Classic. Unless I put my binoviewers in with the diagonal pointing pretty much straight up, the diagonal rotates downwards under the weight. This is both alarming and a major pain in the neck.

Ideas please.

I would consider changing the diagonal and SCT adaptor as solutions, but only if strictly necessary and not too expensive.

[h0ughy (David)]

either you havent locked it off well enough, or you have cross threaded it and it wont lock off. Or your putting the weight on the 9 oclock side , try the opposite side or straight up and down. How long have you had the scope?

[Dennis]

Is there a single grub screw holding the diagonal in the SCT rear adapter? If so, does the grub screw press on the diagonal barrel directly, or does it press on a compression ring?

I removed the compression ring from one of my 2" adapters and drilled and tapped an additional 2 holes at 120 degrees for 2 extra grub screws to prevent my CCD camera from slipping.

Cheers

Dennis

[NightCal]

Originally Posted by Dennis

Is there a single grub screw holding the diagonal in the SCT rear adapter? If so, does the grub screw press on the diagonal barrel directly, or does it press on a compression ring?

Just a single grub screw pressing directly on the diagonal.

[Dennis]

Originally Posted by NightCal

Just a single grub screw pressing directly on the diagonal.

A single locking screw is probably okay to clamp a 1.25 inch diagonal and a 1.25 inch eyepiece, but once you start adding bino viewers and a couple of eyepieces, there is just too much torque so the single locking screw will slip.

I've noticed that US products tend to use locking screws with a 6-32 thread, whereas Japanese products use an M3 thread. These are quite small locking screws.

As mentioned in my initial reply, I had to drill and tap an additional 2 holes at 120 degrees, giving me 3 locking screws in total and this seems to hold my Meade 647 flip mirror and SBIG ST7E ccd camera, which probably induces a torque similar to your bino viewers.

However, I have a 2" fitting but it should be okay on a 1.25 fitting as well.

If you do drill and tap another 2 holes, make sure that you have the correct locking screws. If you lose a screw at an astro camp, you don’t want to be in a position of having to find a non standard lock screw!

On my 2" adapter, I used 8-32 locking screws to make things a little firmer.

Cheers

Dennis

[g__day (Matthew)]

Something I've experienced in this set up, it was the silver tube connecting to the diagonal, not the tube on the diagonal slipping on the OTA's ring.

The first solution was to take out the diagonal and tighten the attachment tube. Once done no more slipping. But I then moved to a BinTel 2" diagonal and the problem didn't re-occur.

You can get glue if its the tube that is slipping in the idagonal itself, rather than just hand tighten it as I did.