Service of Vanox AH rotating stage

[viktor j nilsson]

Hi all,
The Olympus Vanox AH that I picked up this summer came with a nice rotating stage. It rotates fairly smoothly, but the centering mechanism appears to be stuck.



I am not familiar with how rotation and centration mechanisms work. Is it strange that a stage rotates but doesn't centre?

I would very much appreciate input on how to get it apart and fix it. I have not found parts diagram for this exact stage, but it does look similar to the rotating stage for the BH2:



From the drawing, it's not clear to me what i would need to do to get it apart and fix the centering mechanism. If anyone could suggest what they would do I'd appreciate it very much!

[Hobbyst46]

Two thoughts, based just on analogy with the rotating stage on my Zeiss:

1. If the stage allows not only rotation but X and Y translation as well, centration is iteratively achieved : rotate some, shift the stage horizontally, rotate again etc. In principle. Each cycle brings the stage further to a coaxial position.

2. One of the screws might be a locking screw - that locks the rotating part, for shipping or other purpose.

Hope this helps somewhat.

[viktor j nilsson]

Yes, the procedure would be the same for centering this stage, the problem is that the centering knobs (at 7 o'clock and 11 o'clock in my first image) does not move the stage at all.

The knurled knob at 10 o'clock in my first image is a locking screw. If I tighten it, the stage can't rotate.

The lever at 6 o'clock engage or disengage a click at every 45° rotation.

I don't think that there is anything else that I've missed, so I don't think that the problem is user error (but believe me, I always suspect user error first!).

[viktor j nilsson]

I've done some detective work myself without even looking at my own stage.

I had a look at the repair manual for the regular, square Vanox stage. It it's also a rotating stage, but it's not centerable as the round one. But i thought that it might give clues about it's construction, though. Here's what they do to take apart the centering mechanism:


They basically remove that one little plate, 586400, and then the rotating ring 583800 comes free. Here's what it looks like on the parts diagram:



If I look again at the B2-SRP drawing that i first linked to (which is more similar to my Vanox stage), the ZJ 806400 part looks like it's doing a similar thing. I'll try to see if I can find something similar on my stage tomorrow.

[Hobbyst46]

I had a look at the repair manual for the regular, square Vanox stage. It it's also a rotating stage, but it's not centerable as the round one. But i thought that it might give clues about it's construction, though. Here's what they do to take apart the centering mechanism:

Yes, this is a stage I used and dismantled as described) years ago.

[PrecisionInstruments]

The BH2 rotatable stage is very simple.
You would remove, or back off, the cantering screws AA849500. Then pull the stage against the spring pin AA695400, then tilt the rear of stage upwards and out.

It’s possible the banks is the same though you may need to remove the lever that engages the 45* click stop. If so, the lever will be keyed on a square pin, and you will need to take note of placement so you can engage and disengage the click mechanism.

[viktor j nilsson]

The BH2 rotatable stage is very simple.
You would remove, or back off, the cantering screws AA849500. Then pull the stage against the spring pin AA695400, then tilt the rear of stage upwards and out.

It’s possible the banks is the same though you may need to remove the lever that engages the 45* click stop. If so, the lever will be keyed on a square pin, and you will need to take note of placement so you can engage and disengage the click mechanism.

This was extremely informative! The Vanox stage has the centering screws (AA849500 equivalent) mounted in a forward position (as opposed to the BH2 stage). But there is a slot-headed screw at the opposite side, right above the dovetail. This would be the AA695400 equivalent.

Several other spring pins have been stuck from hardened grease on this microscope. So my guess is that the AA695400 spring pin equivalent has become stuck in its innermost position. I thus think my next step will be loosen 2x AA849500 and 1x AA695400, heat the stage with a hair dryer, and see if I can get it off.

[viktor j nilsson]

...aaaaand it's loose!

After loosening the centering screws and the spring screw, I was able to get the centering mechanism moving again. Indeed, I will need to remove the click stop lever to get the top plate off for a proper clean and regrease. I didn't have time to dig out my improvised pin spanner wrench (needle nose clamp pliers holding two pins), so I will need to finish the job later. But it feels good to see it moving again, and to understand the mechansism.

Many thanks, PrecisionInstruments!

Nye 362HB multi purpose grease should work, right? I don't think a dampening grease is appropriate here?

[Rossf]

Glad you got it sorted-seeing those pictures brings me dread-seeing exploded parts diagrams can explode my head! Did manage to follow a pretty simple one for fixing an x/y stage But visually they get very confusing for me very quickly and have to be very strict not to attempt anything past bedtime or big mistakes happen....
Regards Ross

[viktor j nilsson]

Nice and clean before I regreased the stage. Works great now.

[viktor j nilsson]

Ross, I agree, my head can start to spin trying to imagine how all the parts fit together. That's why I made this thread originally, I just couldn't figure out how it was held together. But as soon as you know, it almost becomes obvious.

But I do find the exploded parts extremely helpful when trying to take things apart - and even more valuable when putting them together again!

[Hobbyst46]

...

Congratulations !

[viktor j nilsson]

Thanks Doron!