Stuck diopter adjustment on a Olympus VT II

[Olumin]

Hello,
this is my first official post in this forum (apart from my introduction).
I have recently come to acquire a Olympus VT II stereo microscope from 1978 for use in watchmaking. Its condition is perfect, however an adjustable dial on the left eyepiece does not seem to budge. It appears to be completely frozen in place. I’m I correct in my assumption that this is the dioptre adjustment?

If I am incorrect, please feel free to educate me about the function of this part (pictures attached below).

I cannot detect any damage or corrosion, the condition of this part appears as immaculate as he rest of the microscope, yet it will not move.

Am I overlooking something? Does a screw need to be loosened?

Is there any way or adjusting this dial? Solutions?

Thanks in advance for your help.

Pictures:

[MichaelG.]

My usual first step with this sort of problem [which is not uncommon] is to introduce a small quantity of ‘PlusGas formula A’ into the joint.

This ‘dismantling fluid’ is kerosene-based and will thin most hardened greases very effectively.

... Much better to buy a traditional can than an aerosol.

MichaelG.

[Olumin]

Thank you. Do you believe that simply heating the part as shown in the last picture up and then trying to turn it might be able free it up? Or would that possibly cause any lasting damage?

[apochronaut]

If used by a single owner, the diopter gets set and sometimes never moved for years. The grease dries out and the part is frozen in time.
Dismantling solvent as advised works or I have also used a couple of drops of very light low gassing oil too.
It didn't get tight at the limit of it's travel, so after introducing 2 drops , work it back and forth. Once you get movement, it will either become more and more or level off. Likely two drops will get you somewhere but not enough. Add a drop at a time , after until the action is the way you want it.

It is an external part , so offgassing of any added fluids will enter into the optics minimally but that vintage of microscope probably used Canada Balsam. Not sure if the eyepieces on that have a cemented doublet or not but just be cautious with the solvents, in case there is balsam cement nearby. If you can smell it, so can the lenses.

[MichaelG.]

Thank you. Do you believe that simply heating the part as shown in the last picture up and then trying to turn it might be able free it up? Or would that possibly cause any lasting damage?

I have described, and apochronaut has generally endorsed, what I would do [and have done on many occasions].
Others may step-forward to recommend heating ... but I have only ever used heat as a last resort.

MichaelG.

[Hobbyst46]

...

I would try to locate a manual and even a repair manual for the VT microscope. Alan Wood (see his/Olympus site) is extremely nice and helpful and, in contrast to some other brands, Olympus repair manuals exist.
I will see if my VMZ manual provides any possibly relevant clue.

[Olumin]

The thing with the Plusgas is, while I am sure it would work, it costs like 12,50€ for a 250ml can on amazon, and no stores near me sell it in germany. Well none that I know of.

If you look at my last picture, you can see that the "bezel" of the diopter focusing ring is held on by 3 little slotted screws. I could remove them and try to disassemble the focus ring to clean out the gunk that way? I have no experience with these parts, is the assembly very complex?

[Hobbyst46]

If you look at my last picture, you can see that the "bezel" of the diopter focusing ring is held on by 3 little slotted screws. I could remove them and try to disassemble the focus ring to clean out the gunk that way? I have no experience with these parts, is the assembly very complex?

According to the VM manual, which might resemble the VT-II perhaps, the focusing eyepiece tube assembly consists of a helicoid and two sleeve-like rings. Each sleeve is secured in place by means of three screws - the two screw sets differ in size. A glass circle is glued to the bottom of the sleeve - this detail perhaps does not exist in your model.
FWIW.

[Olumin]

If you look at my last picture, you can see that the "bezel" of the diopter focusing ring is held on by 3 little slotted screws. I could remove them and try to disassemble the focus ring to clean out the gunk that way? I have no experience with these parts, is the assembly very complex?

According to the VM manual, which might resemble the VT-II perhaps, the focusing eyepiece tube assembly consists of a helicoid and two rings. Each ring is secured in place by means of three screws - the two screw sets differ in size. FWIW.

Looking at my part, that probably means the dioper adjust ring has to be screwed-off counter clockwise once the screws are loosend, which I am not able to do as I cannot turn it. Oh well, thank you very much.

[Hobbyst46]

If you look at my last picture, you can see that the "bezel" of the diopter focusing ring is held on by 3 little slotted screws. I could remove them and try to disassemble the focus ring to clean out the gunk that way? I have no experience with these parts, is the assembly very complex?

According to the VM manual, which might resemble the VT-II perhaps, the focusing eyepiece tube assembly consists of a helicoid and two rings. Each ring is secured in place by means of three screws - the two screw sets differ in size. FWIW.

Looking at my part, that probably means the dioper adjust ring has to be screwed-off counter clockwise once the screws are loosend, which I am not able to do as I cannot turn it. Oh well, thank you very much.

In reference to the last photo above, that shows that the eyepiece tube is removed from the scope's head:
According to the VMT manual, each sleeve is secured by means of 3 tiny screws - either set screws or lock screws, I am not sure. The sleeve itself is not threaded. So in theory, once the screws are removed, the sleeve should just fall of the helicoid - unless, of course, it is "glued" to it due to hardened grease.

[Olumin]

According to the VM manual, which might resemble the VT-II perhaps, the focusing eyepiece tube assembly consists of a helicoid and two rings. Each ring is secured in place by means of three screws - the two screw sets differ in size. FWIW.

Looking at my part, that probably means the dioper adjust ring has to be screwed-off counter clockwise once the screws are loosend, which I am not able to do as I cannot turn it. Oh well, thank you very much.

In reference to the last photo above, that shows that the eyepiece tube is removed from the scope's head:
According to the VMT manual, each sleeve is secured by means of 3 tiny screws - either set screws or lock screws, I am not sure. The sleeve itself is not threaded. So in theory, once the screws are removed, the sleeve should just fall of the helicoid - unless, of course, it is "glued" to it due to hardened grease.

All right, so I have decided to unscrew the 3 little screws, and the ring started to turn freely. I was able to take it off and to clean the threads and visible surfaces but there was not much to clean. After reassembling the part and tightening the screws the ring once again is fixed into place. May it be that one HAS to loosen these screws in order to use the diopter adjust? However, when putting the eyepiece back into my microscope and turning the diopter adjust (while these screws are loose), I am unable to detect any difference at either + or - while looking through the left eyepiece. I am able to turn the ring freely 360 degrees but the image does not change. So, I expect this is not the solution?

[MichaelG.]

All right, so I have decided to unscrew the 3 little screws, and the ring started to turn freely. I was able to take it off and to clean the threads and visible surfaces but there was not much to clean. After reassembling the part and tightening the screws the ring once again is fixed into place. May it be that one HAS to loosen these screws in order to use the diopter adjust? However, when putting the eyepiece back into my microscope and turning the diopter adjust (while these screws are loose), I am unable to detect any difference at either + or - while looking through the left eyepiece. I am able to turn the ring freely 360 degrees but the image does not change. So, I expect this is not the solution?

You are now at the point where applying PlusGas [or any reasonable substitute of your choice] to the helical thread would be simple, and should be effective.
I recommended PlusGas because I have used it for decades, and I know it to be ‘safe’ on this type of grease. ... but any similar [kerosene-based] lubricant should work in a similar manner.
Have a look at the constituents of whatever you can buy at a reasonable price.

MichaelG.

[Olumin]

Would you happen to be able to share the diagram of the focusing eyepiece assembly of the VM model previously mentioned by you? It’s still somewhat unclear to me where exactly I am supposed to apply the lubricant.

[MichaelG.]

Here are a couple of quick photos of mine [a similar Olympus stereo] showing the extremes of travel.
... This is what you should be looking to achieve.

Sorry but I really don’t want to dismantle it just now.
... if it ain’t broke, don’t fix it !!

The mechanism is a ‘fast acting’ multi-start thread; just like the focus on a camera lens.
.

48EC2B7D-E8EB-4232-95D9-222C3C32BEB4.jpeg (166.24 KiB) Viewed 10074 times

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0F85BA4D-8712-4646-A0AB-8A7D936DD5C5.jpeg (167.03 KiB) Viewed 10074 times

.

Hopefully that’s all you need to know.

MichaelG.

.
Edit: unless the unit is at its shortest setting, you should be able to see the thread, thus:
.

7236F1F0-D030-4B65-8190-B47C4CE883F3.jpeg (133.93 KiB) Viewed 10071 times

[Hobbyst46]

Would you happen to be able to share the diagram of the focusing eyepiece assembly of the VM model previously mentioned by you? It’s still somewhat unclear to me where exactly I am supposed to apply the lubricant.

Regretfully I cannot share the stuff, it was mailed personally to me only and is not public domain. That is why I suggest that you try to get help from Alan Wood, who is an expert on Olympus microscopes.

[MicroBob]

In Michaels last photo you can barely see the thread with the gummed up lubricant. If you want to apply lubricants it would be the places with the green arrows. To fulla dismaltle and clean the thread you will have to remoce the chromed ring after removing the screws (red arrows)

If I had it dismatled this far with no optics in the way I would not mess around with lubricants but gently warm (hair dryer) to 60-80°C first.

Bob

[MichaelG.]

In Michaels last photo you can barely see the thread with the gummed up lubricant.

Forgive me if I have misunderstood your comment, Bob ... but, just for clarity ... my photo shows a thread which is running very sweetly, and is not at all ‘gummed up’

MichaelG.

[Olumin]

Thank all of you for your help. I have just written Mr. Wood a message in light of my problem. Coming Monday, I will be seeing if there are any suitable dismantling lubricants available at my watchmaking school. Until then.

[Olumin]

Update: Mr. Wood, while not able to provide instructions specific to the VT II, was able to send me documents of comparable models, which helped in the complete disassembly of the entire unit.

At my watchmaking school, I now tried every suitable machine, lubricant and cleaner available to us. I soaked the unit in WD-40 for several hours, as well as in another dismantling lubricant, cleaned it with gasoline, as well as some other quite aggressive vintage cleaning solutions and even ultrasonic cleaning, however none of this worked. The 2 pieces are as frozen as they were in the beginning. I even tried heating but it did not help. I am afraid that I will not be tempering with it any more, as I could possibly damage the parts, or paint, should I be any more aggressive on them.

Unless somebody is able to come up with yet a different approach, I consider this matter closed. At least this part is not crucial for the functioning of the microscope and I will still be able to use it. Thank you very much for you help.

[MicroBob]

The diopter adjustment just changes the length of the eyepiece tubes. If you are not happy with the current setting you can try to adjust it by installing spacer rings below the eyepieces.

[Rorschach]

Would Plusgas work on most eyepieces that are stuck/very rigid, regardless of their age or era? I have some very old ones (Wild, likely 70ies) and some quite new ones (Wild, Leica and Olympus super-wide) that would require attention. After the Plusgas treatment can you just start using the eyepieces with no need to clean off the old lubricants?

[MichaelG.]

Would Plusgas work on most eyepieces that are stuck/very rigid, regardless of their age or era? I have some very old ones (Wild, likely 70ies) and some quite new ones (Wild, Leica and Olympus super-wide) that would require attention. After the Plusgas treatment can you just start using the eyepieces with no need to clean off the old lubricants?

From my personal experience ... applied sparingly, I would say Yes
The PlusGas will simply replace volatiles that have evaporated from the original grease.

But obviously, a full clean and re-grease would be preferable.

MichaelG.

[Rorschach]

From my personal experience ... applied sparingly, I would say Yes
The PlusGas will simply replace volatiles that have evaporated from the original grease.

But obviously, a full clean and re-grease would be preferable.

MichaelG.

Thanks! I'll get some and try it. Will do a more comprehensive clean and re-grease on some of them.