Leitz Orthoplan trinocular: stuck inter-ocular adjustment

[Rorschach]

I am trying to fix the Orthoplan trinocular that I got some weeks ago. It seems to be in good shape otherwise but the the mechanism for adjusting inter-ocular distance is completely stuck. A case of old hardened grease I believe. I know enough not to try to force it by turning the adjustment knob.

I remove the back plate of the trinocular which is held in place by three screws. That offered nice views inside the thing but nothing related to the adjustment mechanism could be accessed from there so I put it back.

Then I removed the two metal barrels that hold the eyepieces (each held in place by four screws). This enabled me to use an air blower to remove dust particles from the lens that sits there.

After that I removed the metal plate that has the letter 'D' on it and that sits between the two eyepiece barrel assemblies. The plate was held in place by four screws.

I then unscrewed the two larger screws that connect each of the eyetube barrels and their plates to the inter-ocular adjustment mechanism (or so it seems). This enabled me to move both of the barrel assemblies back and forth as far as they would slide. They were initially a little stiff but moved without excessive use of force and quite soon they moved a little better. So the main problem seems to be in the adjustment mechanism itself. To get to that I do not really know what to do.

Has anyone disassembled these? If yes, I can provide some pics to illustrate the situation.

[Leitzcycler]

I am not absolutely sure if I understand right the end of your text how you got it moving. However, this is what I remember about the similar situation. In my case the problem was hardened grease between the adjustment axle and the tube inside which it should turn. First remove the screw at the end of the knob. Then you have to pull out the knob. There may be special tools for that but you can try to lift the knob by a screwdriver: put it between the knob and base and bend VERY CAREFULLY. If it does not come off easily, leave it and let's think about a special tool for it (you might also try to use some CRC at this point: see later). Maybe it is a good idea to put some tissue against the surfaces to avoid scrathes. After removing the knob you will see the axle head. The tube is made from two parts and I remember I took the outer part off. There could have been a thread, but I don't remember for sure. However, as you manage to reveal the axle you can put something to dissolve the hardened grease and relubricate. I use CRC 5-56 multipurpose light oil spray: not too much.

[Rorschach]

Ok, here are some pics of the head.

Here is shot of the inter-ocular distance adjustment knob which does not budge at all, not even after squirting a few drops of Ronsonol lighter fluid into the opening in the middle (after removing the screw from there) to try and loosen up dried-up grease. After that I also tried to gently pry the knob mechanism out with a screwdriver, as per to the instructions in the previous message. But it wouldn't budge at all.

Trinocular2.jpg (83.95 KiB) Viewed 4720 times

I then removed the faceplate that sits between the eyepiece tube assemblies. Here is an image of the removed parts:

Trinocular4.jpg (64.13 KiB) Viewed 4720 times

Below is a photo showing in red the location of the two larger screws, which, once removed, allowed me to slide both eyepiece tube assemblies across their whole range.

Trinocular3.jpg (94.29 KiB) Viewed 4720 times

Below is a shot of the lens attachment with the four screws, after removing the eyepiece tube.

Trinocular1.jpg (124.41 KiB) Viewed 4720 times

Below is an exploded view of the head. It seems to me that the prism assembly is attached to the lens so I am hesitant to unscrew those four screws in the previous photo. If the alignment is altered in the process, the thing is probably toast as I do not have the skills or tools to re-align prisms. However, it seems as that may be the only way to access the adjustment mechanism?

Orthoplan_trinocular_exploded_view.jpg (75.1 KiB) Viewed 4720 times

[Leitzcycler]

Try to get the knob warm with a hairdryer. It should be safe to get it warm as it doesn't warm any optical parts.

[Rorschach]

Thanks, I'll try that later.

Meanwhile, I was able to disassemble the vertical adjustment mechanism for the condenser. The adjustment knob and the pinion driving the rack seem fine so I did not touch them. I cleaned all the old grease from the metal sliding surfaces of the dovetail and also the white plastic rack using first lighter fluid and then isopropanol. I have the following greases to choose from: Nyogel 767A, Nyogel 760G and Rheolube 362HB. Need to decide which one to use here and can it be the same one for the plastic rack as for the metal dovetail surfaces.

Edit: It seems the 362HB is recommended for condenser mechanism dovetail gliding surfaces, so I used it:
http://www.microscopy-uk.org.uk/mag/ind ... wlomo.html
Seems to be working nicely.

[Leitzcycler]

I dismantled mine for pictures. I did not remember the axle and sprocket was the same machining. So this means you can apply considrable force without the risk of breaking it. Of course you still have to be careful not to bend the axle head. After remowed the knob you screw the bearing tube out. If you want to do this more professionally you could try to tighten a leather band around the tube and then wind with pliers. I did this with plain pliers as the scratches in the tube head will be inside the knob out of view. But you must touch only the head. Then you just push the axle out of the tube (with the help of CRC and heat if needed). This whole procedure will take a couple of minutes. This is how it goes:

[Leitzcycler]

In case of there are other jams inside the mechanism, I think you will be able to remove the whole assembly by opening the four screws of the bottom plate (number 34 in the exploded view). This is possible only after removing the axle and tube as this lies in a groove of the base. Do not open any screws for lenses and prisms. However I am quite sure that just remowing an relubricating the axle will help.

[Rorschach]

The heat trick did it! I put as hot water as I could get from the tap into a 0.5 liter Minigrip bag (kinda like Ziplock) and placed that alongside the housing where the axle and the tube are. I kept it there for several minutes...and voila! The mechanism started to move! It is still very stiff but I got the full (?) movement from 60-70mm ocular distance.

However, that is only a temporary victory as I still can't get the knob off It won't even budge. I did not try to put crc on it yet because of the risk of some of it entering the head and ending up on the optics. Will maybe try that tomorrow after taping shut all the openings.

Edit: in addition to the condensor mechanism, the other recent and complete success was the disassembly, cleaning and re-lubing of the Orthoplan XY table. It now works nicely. My table is the standard one, without ball bearings and thus (I assume) easier to work with. However, I am lacking the "curved thing" on it, the one which holds a specimen glass in place and has a spring mechanism to tension it. Mine has a different part in stead of that one, no curved part and no spring-tension mechanism.

[Leitzcycler]

Will maybe try that tomorrow after taping shut all the openings.

No, just a drop or two CRC, more won't help. I suggest to heat the knob more. The best solution would be using a miniature puller, but it might be hard to find unless you could make one yourself. Still I think screwdriver should work...

[Rorschach]

You were right, more heat helped. I poured (carefully, so that no water entered the head) boiling water on the knob over the course of a couple minutes. It was still quite stuck but came off! Phew, what a struggle

This evening I will take the axle etc. out and clean plus re-lube. Have to think which of the three greases to use. Also will have to check whether I could clean some of the other parts of the mechanism as well, where the eyepiece tube assemblies slide.

A lot of work but rewarding plus nice savings too comapared to buying a serviced one.

[Scarodactyl]

There's also something extra special about using a scope that you have yourself assembled or fixed.

[Rorschach]

Scaro, you are definitely right about that. It even beats the rewarding feeling of finding a bargain treasure on Ebay.

Leitzcycler, many thanks for your help! I hope I can be of service at some point in return

I will report on how the rest of the process goes. The true usability test isn't in the near future as my eyepieces are still in the US and a few other parts are also missing on the scope.

[Rorschach]

Unfortunately I can't get the bearing tube out. It won't budge.