Quote:
Originally Posted by NightCal
Just a single grub screw pressing directly on the diagonal.
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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