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LX90 Finder scope

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4 replies to this topic

#1 teebark

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Posted 22 November 2019 - 04:32 PM

Why does this finder scope have 2 dummy adjustment screws? The outer adjustment has 2 adjustment screws and one nylon dummy, with no way to adjust the length. There's no slot at the top for a screwdriver to turn it. If you take the scope out, you can turn the screw from the bottom, but you can't do that while the scope is in place. Same thing on the inner adjustment screws, except it's worse. One has the spring loaded, not adjustable screw, and one dummy, which like the other, can only be adjusted after taking the scope out. I've managed to get it in working order by taking the scope out and adjusting the nylon dummy screws, but it was trial and error. Why didn't they put 'real' screws in these place of the dummies. Is there some trick I haven't figured out?



#2 photoracer18

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Posted 22 November 2019 - 05:16 PM

They are just trying to be as cheap as possible.



#3 MikeBY

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Posted 23 November 2019 - 12:41 AM

Because it faces towards the scope they used a knurled thumbscrew (not a dummy) knowing your fingers might reach but a screwdriver or allen key never will have clearance? That'd be my guess.


Edited by MikeBY, 23 November 2019 - 12:45 AM.


#4 Piet Le Roux

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Posted 24 November 2019 - 01:28 PM

1561645025_IMG_1208459.jpg

Why does this finder scope have 2 dummy adjustment screws? The outer adjustment has 2 adjustment screws and one nylon dummy, with no way to adjust the length. There's no slot at the top for a screwdriver to turn it. If you take the scope out, you can turn the screw from the bottom, but you can't do that while the scope is in place. Same thing on the inner adjustment screws, except it's worse. One has the spring loaded, not adjustable screw, and one dummy, which like the other, can only be adjusted after taking the scope out. I've managed to get it in working order by taking the scope out and adjusting the nylon dummy screws, but it was trial and error. Why didn't they put 'real' screws in these place of the dummies. Is there some trick I haven't figured out?

It should have 5 thumbscrews with nylon tips and one spring loaded dummy with a plastic tip. The idea is to adjust the front 3 screws by hand so the scope is in the middle of the mount and the two thumbscrews at the rear to get it in the middle and then you can adjust the two rear thumbscrews to get two axes of travel. 



#5 MikeBY

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Posted 26 November 2019 - 05:04 AM

There are no "dummy" screws. You should never have anything so tight you would need a screwdriver to tighten or loosen it. If so, you'll likely be putting a dimple in the scope tube. If you've got metal screws without a plastic/nylon tip you'll cut into the paint and the metal immediately.
I have an old meade LX OTA that had stainless cap screws in the finderscope rings when I bought it and of course the finder has damage. Kind of a shame really.
Looking at Piet's picture I don't understand why they didn't just use nylon screws to begin with. Piet explains why there is a spring loaded pin in the back. it GREATLY simplifies alignment of the finder that you are only moving two screws and have spring tension rather than three in various loosen/tighten combinations.
The best source I've found for nylon thumbscrews in a variety of sizes and at a cheap price is Grainger.
My experience with popular local hardware stores is that selection is limited.

Clear skies!
Michael


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