Has anyone solved the mirror flop on the 12" lightbridge.

[White Rabbit]

I've never been happy with the smudged view at certain elevations on my Lightbridge and it's due to the mirror flop. Have any owners out there solved it.?

Thanks

[goober (Doug)]

Not sure what mirror flop is, but my departed 12" dob received much stiffer primary mirror springs real quick, and some bobs knobs.

[Robh (Rob)]

The springs were so puny on my 12 inch Lightbridge that I had to use the locking screws to actually collimate the primary mirror. It wasn't until I got a stiffer set of springs* from Bintel that I could revert to the usual collimation screws to do the alignment. (*Bob's Knobs Meade Lightbridge Springs).

Regards, Rob.

[astronut (John)]

I agree with Doug & Rob,
Stiffer springs will cure the problem, this will also allow you to get rid of the locking pins.
Since they are in the wrong position they are actually another set of collimation pins.
To be proper locking pins, they should be mounted next to the collimation knobs like the Skywatcher scopes.
I replaced the knobs and springs immediately after purchase in 03/06 and have never suffered mirror flop.

[Quark (Trevor)]

I have a 12" LB as a second scope to take out and about. I replaced the springs in the primary mirror cell before I used it and have removed the locking screws, which are in the wrong place anyway. I also have Bobs knobs for the primary and secondary.

Why Meade would build a truss Dob with only 3 sets of tubes is beyond me. I think you will find that there is movement between the top and bottom end of the scope also. With my particular LB I found that the lugs on the clamping brackets bottomed out before the clamp tightened up on the truss tube ends.

I measured the length of the lug and the thickness of the truss tube ends with a vernier caliper and found that the lugs was close to 1/16" to long. I filed the lugs down until they were 1/32" less than the thickness of the tress tube ends. Now, when I tighten the clamps they actually lock the tube ends.

To test if this is a problem with your LB, leave the top end off of your scope and just tighten the tubes into the brackets on the bottom end of your scope. Gently try and rock the tubes, if like my scope was originally, they move within the tightened bracket then imagine what happens when the top end is in place and you are moving your scope in alt and az.

I have made many other mods to the LB and it works quite well now but I would still prefer to see them with 4 sets of struts instead of only 3.

Regards
Trevor

[astro_nutt]

If you can remove one of the springs, take it to a Bunnings store and get something better in the compression spring department. Whilst you have the mirror cell apart, give it a good clean and put some decent grease on the bolt threads. Don't forget to use flat washers top and bottom with the new springs.
Cheers!

[White Rabbit]

Thanks guys, I should have mentioned that I have bobs knobs and springs on my 12".

I might take a look a bunnings tomorrow and see if I can pick up stiffer springs.

Cheers

[astronut (John)]

How is the mirror attached to the cell? Adhesive pads?