Nikon MM-11 tension ring (problem)

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 10:31 am

I'm not familiar with microscopes in general. Yesterday while practicing my shooting technique I noticed the fine focus knob slowly moved away from the witness mark tape I placed near the knob (not shown in these images). I asked ChrisS privately about this and he gave a suggestions ... and now I"m here to make sure I'm using this correctly, like no guessing.

So how does this work. It 'seems" (note the seems) that if I grab both of the larger fine focus knobs and turn one the opposite direction of the other that it acts like a clutch and tightening the smaller fine focus knob and eliminating the creep?

Also, the narrow ribbed larger knob has 2 set screws in it. You can see them in the second image below. It doesn't seem to move at all IF I try to rotate it by hand but I didn't try and force. It seems to be independent of the other larger knob next to it.

Lastly, the larger tension knobs (last image below) perhaps works the same way?

Anyone actually know exactly how 'both' of these work?
-JW:

Pau · Post by **Pau** » Sun Nov 13, 2016 10:45 am

So how does this work. It 'seems" (note the seems) that if I grab both of the larger fine focus knobs and turn one the opposite direction of the other that it acts like a clutch and tightening the smaller fine focus knob and eliminating the creep?

I don't know with Nikon, some focus blocks like the Wild stereos work this way while doing it with others like Olympus can dismount or even damage the mechanics, so better wait experienced opinions before forcing it.

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 11:15 am

Thanks ... that's why I came here. <g>

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 11:55 am

I'm pretty positive that something is wrong like a broken nylon gear like I read in another posting on a different scope. I can feel it in the fine focus at certain places. Pretty odd since I didn't feel this before when I shot some minor test stacks. It seems after about 20 complete 360 degree rotations the problem started. Sweet, just want I needed, something else to repair or another door stop. Hopefully it can be fixed. In any case I still want to know how it's supposed to function, plus if anyone has disassembled one of these focus mechanism a part.

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 1:45 pm

So I started disassembling this puppy. I stopped here since I'm not sure what the next step is without messing something up. I would assume taking the three screws out shown in the last image below but was concerned the gears and who knows what else might turn into a nightmare upon reassembly. <g> Anyone in the know please jump in.

-JW:

Choronzon · Post by **Choronzon** » Sun Nov 13, 2016 2:28 pm

In the last photo, does the carriage move up and down smoothly then lifted by hand, the small gear spinning around without a lump?
If yes, then the problem lies within photo #4. Pry the metal cover off the knob , exposing the 3 screws attaching the brass gear case underneath. Inspect all gears for damage

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 3:47 pm

Choronzon wrote:In the last photo, does the carriage move up and down smoothly then lifted by hand, the small gear spinning around without a lump?
If yes, then the problem lies within photo #4. Pry the metal cover off the knob , exposing the 3 screws attaching the brass gear case underneath. Inspect all gears for damage

When moving the carriage up and down by hand it seems to move very smoothly without any glitches. I also inspected the two gears in photo #6 (the one with the shaft looking at you where you can see the gears on the inside of the dial) and #7 (where it's attached to the focus block riser) with a magnifying glass and the teeth look fine to me. Also, when I lightly pried the thin metal cover ring off there isn't much to see in there (see attached photo). I DID NOT take out the three screws that were underneath the cover thinking it wasn't necessary since I can see the gears on the other side? The shaft seems to turn fine without noticeable glitches.

-JW:

-----

One addition question, by me not understanding the operation of the MM-11, could it be I reached the maximum 'throw limits' (meaning I hit the bottom and it couldn't move downwards any further) and this caused whatever is going on and perhaps I should put it all back together?

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 3:51 pm

... update coming ...

Choronzon · Post by **Choronzon** » Sun Nov 13, 2016 3:54 pm

You've come this far, take out the 3 screws and look at the gears and fine adj shaft gear underneath the gear case.
Also is there a nylon washer for each fine adjustment knob when you took them off? I see one and the wave washer, it is there another nylon washer for the other fine adj knob?

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 5:54 pm

Here are few more pictures. Yes it's the little pinion gear, two teeth are history. You can sort of make it out in the first picture below. I couldn't hold the camera still in the last pic but you'll get the idea.

-JW:

mjkzz · Post by **mjkzz** » Sun Nov 13, 2016 6:04 pm

Is it a plastic gear? If so, I can not believe with all these metal stuff, they put in a plastic one at the critical part!

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 6:19 pm

Choronzon wrote:Also is there a nylon washer for each fine adjustment knob when you took them off? I see one and the wave washer, it is there another nylon washer for the other fine adj knob?

Here's what I have ... stuff on the left is for the left dial, stuff on the right is for the right dial.

-JW:

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 6:26 pm

mjkzz wrote:Is it a plastic gear? If so, I can not believe with all these metal stuff, they put in a plastic one at the critical part!

Nylon, Acetal gear or something. They probably didn't want to destroy the other gears and this is the weak link.

-JW:

rjlittlefield · Post by **rjlittlefield** » Sun Nov 13, 2016 8:42 pm

Smokedaddy wrote:They probably didn't want to destroy the other gears and this is the weak link.

I'm not familiar with this particular model of focus block. But I am all too familiar with the Labophot 2 block, and in that case the vulnerability of the small plastic gear looks like the designer just didn't think hard enough about how the equipment might be handled. See discussion at http://www.photomacrography.net/forum/v ... hp?t=27917.

I'm pretty positive that something is wrong like a broken nylon gear like I read in another posting on a different scope. I can feel it in the fine focus at certain places. Pretty odd since I didn't feel this before when I shot some minor test stacks.

Again, I'm not familiar with this particular model of focus block. But with the Labophot 2, the small plastic gear is easily damaged by turning the two fine focus knobs against each other, as I did. I can easily imagine that the gear was fine when you started, and broken some time later, due to something like that.

--Rik

Smokedaddy · Post by **Smokedaddy** » Sun Nov 13, 2016 8:44 pm

I remember reading your thread BEFORE this happened to me. Any clue where I can find one?

-JW: