Zeiss centerable rotating stage questions

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hans
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Zeiss centerable rotating stage questions

#1 Post by hans » Tue Jun 29, 2021 3:23 am

I bought a stage that looks identical to Kurt's in this thread except the part number is 4661015: https://www.microbehunter.com/microscop ... hp?t=10177

Same symptom too: rotation locks firmly when the thumbscrew is tightened and is reasonably free when it is loosened but only about 1 mm travel of the inner ring relative to the outer before feeling like it hits a firm stop in either direction.

I also notice the leadscrew-driven axis has a fair amount of backlash but I don't have any other stages with leadscrews and I'm not sure how much is expected. The backlash corresponds to about 2 mm at the periphery of the 15 mm diameter knob and feels fairly consistent across the entire travel. Is there a way to adjust backlash if the stage is disassembled?

Finally, the thumbscrew 3 that is labeled as adjusting stiffness of motion of the Y axis on the 47 34 56 stage in the Photomicroscope III manual (which also looks similar to mine) has no effect when tightened. With the axis moved all the way back and looking in underneath I can see where it looks like a mechanism near the screw is supposed to clamp the slide but can't tell what exactly is supposed to be happening or why it is not working.

Otherwise the stage seems fine. The centering adjustment works and the X/Y axes move freely with no play in the slides. The rotation problem hopefully would be a simple fix like Kurt's but the X axis backlash worries me if the nut might be worn without any way to adjust. Opinions?

hans
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Re: Zeiss centerable rotating stage questions

#2 Post by hans » Tue Jun 29, 2021 3:43 am

For convenience here is the diagram from the Photomicroscope III manual I was looking at, screw 3 doesn't seem to do anything.
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75RR
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Re: Zeiss centerable rotating stage questions

#3 Post by 75RR » Tue Jun 29, 2021 5:04 am

.
If you are disassembling, then photos of where you are stuck might help with suggestions
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MichaelG.
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Re: Zeiss centerable rotating stage questions

#4 Post by MichaelG. » Tue Jun 29, 2021 6:55 am

My guess is that screw [3] actually applies a ‘brake pad’ … and that this is sticky with hardened grease, which may cause it to tilt and jam with slight rotation of the stage.
N.B. __ Having never dismantled one; this is a guess !

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hans
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Re: Zeiss centerable rotating stage questions

#5 Post by hans » Tue Jun 29, 2021 9:31 am

I received it a few days ago, waiting for seller to respond, so I have not done any disassembly beyond loosening the centering screws and separating the stage from the mounting arm and lower part of the centering mechanism as shown in Kurt's post #6.

The rotation behavior is exactly as Kurt describes due to the bearing being assembled incorrectly so I was actually not too worried about that problem, assuming I can get the stage apart, which I would probably try to do anyways for ease of cleaning. I can see the brake (layered, circular thing in the outer ring visible in Kurt's post #11 which is controlled by screw 2 in the diagram) and am pretty sure it is not the problem.

The backlash in the X axis, if due to wear and not adjustable, would be annoying in use I think. It is a lot more than the rack-and-pinion Y axis has, and a lot more then I am used to in well-adjusted rack-and-pinion stages like the AO/Reichert ones.

Not sure abut screw 3 for the Y axis, whether it is just to control resistance (which seems ok as is) and lock against accidental movement, or has some other more important use?

So basically I was just hoping to get some input on whether any of these issues are likely to be unrepairable before deciding whether to return or take a partial refund.

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Re: Zeiss centerable rotating stage questions

#6 Post by MichaelG. » Tue Jun 29, 2021 12:21 pm

Apologies, Hans … I misinterpreted the function of screw 3

[blame it on depleted caffeine level]

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Re: Zeiss centerable rotating stage questions

#7 Post by 75RR » Tue Jun 29, 2021 1:01 pm

.
If it hasn't been dropped (signs are bent knobs or broken pins in the X axis slide holder - it is a heavy beast) then go ahead and open it up.

By the way, the condenser holder, assuming you don't have a WL, Universal or Phomi (or don't need a spare if you do), is worth something.

The number you quoted: 4661015 is not a catalog number but the serial number.

Catalog number would be either 47 35 56 or 47 35 57
.
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Re: Zeiss centerable rotating stage questions

#8 Post by hans » Tue Jun 29, 2021 6:38 pm

75RR wrote:
Tue Jun 29, 2021 1:01 pm
By the way, the condenser holder, assuming you don't have a WL, Universal or Phomi (or don't need a spare if you do), is worth something.
It didn't come with a condenser holder, and I don't see an obvious place one would attach directly to the right-angle arm that supports the stage. Was thinking maybe the condenser holder would independently clamp to the same dovetail rail the stage does, how do they normally mount?

I was thinking I would try to adapt it onto the combined condenser/stage mount from a Microstar IV, keeping only the rotating part of the Zeiss with the Zeiss right-angle mounting arm removed, similar to Kurt's older thread:
https://www.microbehunter.com/microscop ... =24&t=9924
75RR wrote:
Tue Jun 29, 2021 1:01 pm
The number you quoted: 4661015 is not a catalog number but the serial number.
Good to know, would have saved me a good 30 minutes of futile searching. I saw photos of other stages with the catalog number in the same location, Zeiss is not making it easy...
75RR wrote:
Tue Jun 29, 2021 1:01 pm
Catalog number would be either 47 35 56 or 47 35 57
It is 47 35 56 without angle graduations, unfortunately. Those would be nice to have but rotating stages with angle graduations, especially the ones designed specific for polarization work, seem to be a lot less common and more expensive.

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Re: Zeiss centerable rotating stage questions

#9 Post by 75RR » Tue Jun 29, 2021 6:59 pm

It didn't come with a condenser holder, and I don't see an obvious place one would attach directly to the right-angle arm that supports the stage.
I think what you are calling the right angled arm is in fact the stage holder. Designed to fit just the WL, Universal or Photomicroscope.

Took the liberty of doing a search for your stage, image shows the stage holder.
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Re: Zeiss centerable rotating stage questions

#10 Post by hans » Tue Jun 29, 2021 8:07 pm

Attaching photos of the stage holder it came with, but confused, did you mean to say stage holder rather than condenser holder in the earlier post:
75RR wrote:
Tue Jun 29, 2021 1:01 pm
By the way, the condenser holder, assuming you don't have a WL, Universal or Phomi (or don't need a spare if you do), is worth something.
This page maybe shows the stage holder I have, which looks like a completely separate part from the condenser holder?
http://www.microscopy-uk.org.uk/mag/art ... w-pm3.html
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Re: Zeiss centerable rotating stage questions

#11 Post by 75RR » Tue Jun 29, 2021 8:13 pm

Attaching photos of the stage holder it came with, but confused, did you mean to say stage holder rather than condenser holder in the earlier post:
I did, sorry, my bad!

Thanks for the photos.

The stage holder, the 'L' shape part that holds the stage base by the 4 screws, is worth about a third of what you paid for the complete rotary stage.

So some compensation there if you don't need to use it.
.
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Re: Zeiss centerable rotating stage questions

#12 Post by hans » Sat Jul 31, 2021 10:01 pm

75RR wrote:
Tue Jun 29, 2021 8:13 pm
...is worth about a third of what you paid for the complete rotary stage.
I guess confusing the serial number for a part number removed all doubt... Thanks for the suggestions, haven't fully cleaned/relubricated it yet but did end up keeping it after disassembling enough to determine that all the issues were hard grease:
  • Rotation locked with slight free play -- the balls can roll through the hard grease but the cages are completely stuck. So the free play corresponds to the distance the balls can roll in either direction before hitting the cages.
  • Excessive X axis backlash -- little spring-loaded plastic bushing piece normally presses the screw against the half lead nut to take out backlash but plastic bushing is stuck away from the screw in the fully compressed position by dried grease. Also a little axial play in the screw contributing to backlash which can be adjusted when threading the knob on before tightening the locknut.
  • The clamping piece that screw 3 presses on is seized with dried grease.

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