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Diopter Jammed

Posted: Fri Mar 02, 2018 6:07 pm
by Grif
Working on a nice

MAGNA No 51051 binocular
Tagged as made in Occupied Japan

Things coming along nicely, I've not done any damage yet, a previous post said something about Russian Tank tread grease? Well,,, yup, and it's likely not been moved in 30 years. All the rack and pinions were unable to be moved...ALL were locked up solid. A bit of warm, a soak with some penetrating oil and things are getting apart and cleaned up.

(yes, all the optics are off and safe, except the prism head).

I've got the diopter tube off. (single set screw), mostly grease that's turned to locktite to remove it,,, but it's off and cleaned up.

The adjustment will not budge. When mounted on the head,,, it's about 1/8 inch shorter than the stationary tube, I assume it was screwed down tight at one time and left to harden. So, before I get serious about it I'll do the obvious and ask.... any hints? I did a search, I'm also aware of the Microscopy site, and there is one group on Yahoo as well,,,

Here's the big question.....
Looking down at the top of the microscope. If I turn the diopter adjustment collar counter clockwise, does that shorten the tube, or lengthen it?

So, I've looked for any obvious micro sized screws, none found, added some penetrating oil a few days ago.

Here's the plan.

hair dryer till it's good and hot. Then a total soak in penetrating oil and leave it a few days.
Heat it back up and hope for the best with a strap wrench (after I'm sure which way to turn it).

If that does not work.... I'll cut an arbor for a light press fit out of brass (nice shop), and locktite it on, and use that for some extra leverage against the adjustment collar. After that,,, I'll likely be in the market for a replacement tube :mrgreen:

Re: Diopter Jammed

Posted: Fri Mar 02, 2018 9:45 pm
by lorez
A photo would be helpful.

Although I've never heard of the brand you mention, the fact it's from Occupied Japan does lend a bit of insight. I'll put my money on the diopter tube extending as you turn the ring counterclockwise as seen from the top.

I think the heat would help, but I would not use the penetrating oil.