Lomo 85x/1.0 coverglass ring stuck

[LomoBen]

Hello, my name is Ben and I am new here on the forum, yesterday I have filled in my introduction.
Now I have the following question, I have the Lomo 85x/1.0 waterimmersion objective with adjustable coverglassring which is really stuck, not moveable.
So I have found this for solution:
http://www.microscopy-uk.org.uk/mag/ind ... ource.html
But to dismantle the lenscap is quitte difficult, because this is stuck as well, not any movenent in this.
Does somebody have ideas to get it loose?
The coverglass ring stays on 17 permanently and I would like to get it moveable again.
Regards from Poland.
Ben.

[apochronaut]

This is a very common problem, not only with Lomo but Lomo are particularly prone to it. Probably the grease or petroleum jelly they used was very pure, without many additives, so it's volatile compounds evaporated easily.

Objectives sometimes have tiny screws with stripped heads or seized collar threads which make disassembly difficult and there is only so much time one can spend on an objective of limited value, so one way I have found to get them working is to drop one drop of pure light oil into the upper and lower seams of the ring. If it is dropped accurately it will wick into the seam or can be mostly guided in with a small tool. Let it sit for a day and then try to move the ring. If it moves at all, keep trying to work it back and forth. It will likely need another drop in each seam then, leaving time for the oil to work in: or maybe 3 but I would not exceed 3. I have been using NYE light viscosity oil PP269 .

The idea is for the grease to take up the oil or become an emmulsion with the oil , which will thin and liquify it sufficiently to allow the ring to move. Too much oil could bypass the grease layer and get into the lens elements, so you have to be very careful.

I have done over 10 such objectives in this way and all have been successfull to varying degrees and I have not yet fouled an objective. However, some years ago I gave similar advice to a forum member and he greatly overdid the oil. He must have used about 10 or more drops and completely fouled an AO L.W.D. 45X. I ended up having him mail it to me and I repaired it for him, since I felt guilty of encouraging him but my current disclaimer is; I am not squeezing the oil can.

Obviously, disassembling the mechanism, cleaning and relubing it properly is the best way but if that cannot be done, the above method works if carefully accomplished.
I wouldn't say no to helping someone defoul an objective, though but my current circumstance puts the finish date on one, definitely into the future.

[LomoBen]

Hello Apochronaut,
Thanks for the information, I will try it with thin oil.
Yes I am familiar with the Soviet grease used in their microscopes, around 2014 I found my Biolam miscroscope back and the first thing I noticed that course and fine focus was completely seized.
So then I took it apart ,cleaned it and regreased it and worked fine...
Because I emigrated from Holland to Poland I did not use the microscope for a couple of years...
Last week I decided to take time for it again and now I found out that the condensor was not moving anymore, so I fixed that as well.
And for now this objective.
I will let you know when it is succesfull.
Regards, Ben.

[patta]

I've disassembled this objective a few months ago, doing a bad mistake.
You don't really need to disassemble anything. Try with light oil as from previous post (and wait overnight...).
very important:
take plenty of PHOTOS of the coverslip thickness scale, mark where it is, mark where the ring is, etc: otherwise you won't be able to reassemble it in the same position and with the same calibration! I didn't.
After taking the photos, loosen a bit the three small screws on the scale ring (don't unscrew them completely or they'll disappear) - so it is free to rotate; now, you can apply brute force to turn the knurled correction ring above. Once you managed to get it to turn, done, you'll fasten again the scale ring where was before.

For full disassembly:
take 10 photos
the tip (with 85x) can be unscrewed
mark on the brass barrel where the "10" is
loosen the 3 grub screws on the scale ring, then it comes out
the top baffle can be unscrewed, then another ring underneath needs to be unscrewed, so a spring comes out
you can then unscrew the movable lens by rotating the collar, but before that try to screw it down, and write how many turns it takes to go to bottom;
Once you've fully unscrewed the inner movable lens barrel, before extracting it, mark from which side of the barrel it goes in...
the top two lenses remain in place. You can unscrew them from the front.
don't loose the little tab between the scale ring and the knurled one...

[patta]

Oh sorry just read the "correction collar manteinance" link at post #1
The link for the 40x repair, that is much better than my instructions, and 40x has identical construction than the 85x. Below, some scuffs on the cap. Not sure if it was me or previous owners.
so, wait for the oil to do its job....

[LomoBen]

Thanks Patta for the reply, as from now with a drop of oil the coverslip ring is working again, so far so good.
But I wonder leave it as it is, or take the objective apart for fully regrease?
My problem with this objective that the lenscap or tip as you name it , will not come loose, or does it need also a drop of oil?
And the spring on the photo, for what purpose is it? I think not for protection the specimen, because I don't see any movements, unlike objectives 40/0,65 or 90/1.25 ?
Ben.

[patta]

the spring, it is to keep the coverslip adjustment tight
To take out the adjustment mechanism, you don't need to remove the cap with 85x; the moving barrel comes out from the top. Need to screw out the black baffle (likely stuck as well) and the ring underneath. And loosen the grub screws in the scale ring. Take photos!

[LomoBen]

OK, thanks.
For the moment I make not yet the decision to take it apart completely,but for now I think I have enough information.

[patta]

OK, thanks.
For the moment I make not yet the decision to take it apart completely,but for now I think I have enough information.

Don't forget to take photos!!

[LomoBen]

Yes I will do so if I take it apart, better more photo's than less.

[PeteM]

Should you decide to take this part, some aids to getting that cover off.

1) A pair of "connector pliers" or equivalent soft-faced pliers to firmly grip the cover and back knurled ring.

2) Gentle application of a bit of heat and a drop or two of solvent. For heat, I use a pencil-type heat gun. You want to expand the outer cover, without getting the lenses hot.

3) If the soft-faced pliers fail, I use 5c collets and a collet chuck (or lathe spindle locked in place) to firmly grip parts without marring them.

In my own case of disassembling a very stuck Lomo 85x of the same sort, the cover came off with the pliers and a bit of heat. However the engraved correction ring was so thoroughly "glued" even after removing the 3 setscrews and applying solvent and heat - I needed the better grip of a collet.

I suspect the lubricant used in my case attacks brass. This is the case when sulfur is added to the oil as an anti-oxidant. It hard turned to a sort of copper and crusty brown color and might as well have been glue.

[LomoBen]

Thanks for the advise...
Good tips ...
Ben.

[LomoBen]

I was able to remove the lenscap by applying heat from a hairdryer on the lowest heat position and checked temperature with a digital meter, so on exact 40 degrees Celsius I was able to loosen the lenscap .
Tomorrow will go further ....

[LomoBen]

Finally, after taking everything apart, cleaned it thoroughly , put several marks and making a lot of photo's , relubed it with special grease for instruments, replaced all the parts back again.
Now working fine. I thank everybody on this forum for the tips as well as Mr. Sterrenburg on Micscape for his contribution on that site. See above on my first comment.
Note that the old Russian grease went into green color.
Ben.

[PeteM]

Glad you have it restored, Ben. This is one of the few comparatively affordable higher magnification water immersion objectives available.

[LomoBen]

Thanks Pete, yes I am glad that it works fine now, it was a new experience and not that easy because about everything was stuck, starting with the lenscap to dismantle.
Hope to find one day a nice 60x waterimmersion to complete it, have the 40x waterimmersion as well.

[apochronaut]

That's great that you got that cleaned and lubricated properly. They are a pretty good objective when working well but very finnicky as to whether you can even focus them with thicker cover slips.

[LomoBen]

Ok, thanks I will remember that...

[zzffnn]

Thanks Pete, yes I am glad that it works fine now, it was a new experience and not that easy because about everything was stuck, starting with the lenscap to dismantle.
Hope to find one day a nice 60x waterimmersion to complete it, have the 40x waterimmersion as well.

LOMO 60x is for no cover dipping.

65x NA 1.1 works very well and better than 70x NA 1.23 in my hands. My version of 70x is has tight working distance and lower contrast.

[LomoBen]

Thanks for the info zzffnn, keep that in mind.
Ben.

[apochronaut]

The only way I found to use the 70X 1.23 W.I. was with the thinnest cover slip possible, around a .10. It definitely isn't for samples containing any large material, either.
I now have some quartz cover slips. It might do better with those.

[LomoBen]

Ok, never heard about quartz coverslips, seems I am getting old ...

[apochronaut]

lower N.A., and uv transparent, so essentially designed for fluorescence but they should do better with water but almost perfect with glycerine ( 1.47 vs. 1.48).
If anyone wants any( slides too), I can get a pretty good factory deal. Ted Pella wants approx. 20.00 each for each cover slip.

[LomoBen]

Never to old to learn. Thanks Apochronaut .
Ben.