Reassembly of the leaves of the field diaphragm of a Zeiss PM3

[tlansing]

I have some questions about reassembly of the field diaphragm on a Zeiss Photomicroscope III. This is the “newer” version of the diaphragm with a plastic wheel that opens and closes the leaves of the diaphragm (photo 1). I removed the glass window that covers the leaves of the diaphragm and I lifted the plastic wheel which also lifted the mechanism (photo 2) that is attached to the leaves and opens and closes them. The leaves then became detached from the base of the iris diaphragm (photo 3), requiring them to be reassembled. So far I have figured out that the 2 pins on each leaf (photo 4, one on each side of each leaf) go into different holes in the mechanism in photo 2 and the base of the diaphragm in photo 3. However, after some testing it seems to me that there is a particular order to placing the leaves on the base of the iris before replacing the opening and closing mechanism. I would appreciate any advice on how to reassemble the leaves.

Additionally, I have a complete metal field diaphragm that I could just replace the plastic version. If I do this, is there any additional alignment that needs to be done or can I just replace it and everything is fine?

Tim

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[Hobbyst46]

This may help some, maybe see #8 (or #18 ?) of the following previous post:
Re: Help needed - 1) Faulty phase contrast, 2) re-assembly of field diaphragm leaves Zeiss standards

Often questions about Zeiss are answered in detail on the German forum.

[tlansing]

@Hobbyst46: Thanks for your link to your previous post about this topic. Like you, I often go to the German forum to get detailed answers about everything Zeiss (and much more). I also posted my question about reassembly of the luminous field diaphragm and received from very helpful advice and comments. The thread can be found here: https://www.mikroskopie-forum.de/index. ... ic=47593.0. Thank goodness for Google Translate and DeepL!

[PeteM]

Tim, If the pins on each end are intact, you should be able to weave them back into place. Even if one leaf is damaged and needs to be omitted, the iris will usually be approximately good enough to be useful in controlling light into the condenser.

One pin end goes down into the base and another goes up into the top slot. It's best to orient the leaves to the maximum diameter as you put one over the other, since the mechanism constrains them and helps put pins in place.

Things typically go fine, one on top of the other, until you need to start tucking leaves into ones already in place. At that point, you (I) start feeling fumble-fingered as every attempt to add a new leaf displaces one already there. The trick is to hold them in place with some sort of gentle clamp. An example for thinner iris mechanisms, somewhere on this forum, would be cheap plastic tweezers to which a clamp screw has been added. Ingenuity will lead to dozens of other options.

Good luck.

[tlansing]

Hi Pete, what you describe is exactly what I did as described in my previous post in this string. I tried several different approaches before I got to the one that worked; a YouTube video was helpful (https://www.youtube.com/watch?v=oH6GfyxpK9o). Patience was a key ingredient to success.

Tim