Nikon Fluor 40x frozen collar + front element

[karhukainen]

I got this objective from Ebay and it was supposed to be in good working condition, but both the correction collar and the front element are stuck. I was promised a full refund and will get to keep the objective, so now I can try to fix it. Any thoughts on how to start?

[karhukainen]

Apochronaut mentions Nye PP269 oil in some other thread concerning a stuck iris, but I couldn't find this oil for sale anywhere. It was also mentioned that lubricating a frozen cover glass adjustment collar can be more risky optics-wise and shouldn't necessarily be done without disassembling the objective. Since I got this one for free, I thought it might be interesting to try and fix it. What materials/tools would I need and what things should I take into consideration? Has anyone on here disassembled this particular objective?

[zzffnn]

I don’t have the exact objective and don’t remember exactly how I released my objective iris or correction collar. I did it successfully with two objectives and have not destroyed any.

I think what I did was either applying 2-3 tiny drops of xylene by micro pipette or heating, then turning by force. Drops should be as little as possible. But I think heating would be safer; heat to warm to touch, but not to burning hot.

Turn it by force, using a table vise to grip it, then turn with a regular wrench with paper towel padding.

[karhukainen]

I don’t have the exact objective and don’t remember exactly how I released my objective iris or correction collar. I did it successfully with two objectives and have not destroyed any.

I think what I did was either applying 2-3 tiny drops of xylene by micro pipette or heating, then turning by force. Drops should be as little as possible. But I think heating would be safer; heat to warm to touch, but not to burning hot.

Turn it by force, using a table vise to grip it, then turn with a regular wrench with paper towel padding.

What about afterwards, if this approach works? Wouldn't it likely get stuck again unless it's cleaned/lubricated? And what to do about the front element that's also stuck?

[zzffnn]

^ So far, all my iris objectives work just fine (none becomes stuck again after I released them about 3-6 years ago). Only one objective take some effort to turn but still works.

The things about tiny iris leaves is that if you mess them up, they are a huge pain to put back.

I have not worked on stuck front element.

[apochronaut]

It has been a while since I repaired on of those or similarly constructed. The memory banks are full and in need of advice on how to get them unstuck.
Just one thing. That JIS screw that sits in the grip ring looks a bit out of place. I might be wrong but is it an original?

[karhukainen]

It has been a while since I repaired on of those or similarly constructed. The memory banks are full and in need of advice on how to get them unstuck.
Just one thing. That JIS screw that sits in the grip ring looks a bit out of place. I might be wrong but is it an original?

I wondered about the screw myself. I don't think it's original, looks far too big.

[karhukainen]

^ So far, all my iris objectives work just fine (none becomes stuck again after I released them about 3-6 years ago). Only one objective take some effort to turn but still works.

The things about tiny iris leaves is that if you mess them up, they are a huge pain to put back.

Yeah, that's something I don't need to worry about with this objective. But maybe I'll try heat and force a bit more before attempting anything else.

[viktor j nilsson]

I've fixed the collar on a very similar Nikon CFN Planapo 40x 0.95. You just loosen the screws, which releases the rotating ring. Then you can clean and lubricate the mating surfaces. I don't think they are locked in place, but maybe add a tiny drop of acetone on each screw just in case.

Although in other cases I've been successful just adding a tiny amount of oil at the seam, heating gently with a hair dryer, and working it loose. Still working a couple of years later.

The 40x 0.85 Fluor is pretty nice, huge upgrade from a regular 40x and really easy to use.

[karhukainen]

I've fixed the collar on a very similar Nikon CFN Planapo 40x 0.95. You just loosen the screws, which releases the rotating ring. Then you can clean and lubricate the mating surfaces. I don't think they are locked in place, but maybe add a tiny drop of acetone on each screw just in case.

Although in other cases I've been successful just adding a tiny amount of oil at the seam, heating gently with a hair dryer, and working it loose. Still working a couple of years later.

The 40x 0.85 Fluor is pretty nice, huge upgrade from a regular 40x and really easy to use.

Thanks! Which lubricant/oil do you use?

[viktor j nilsson]

Thanks! Which lubricant/oil do you use?

The light oil from the Nye hobbyist kit.

[karhukainen]

Thanks! Which lubricant/oil do you use?

The light oil from the Nye hobbyist kit.

Do you know if it's been discontinued or perhaps renamed? I couldn't find this kit for sale anywhere, (I checked Micro Tools). There's one kit on Ebay, but who knows what those bottles really contain.

[viktor j nilsson]

I got my kit from Newgate Simms several years ago, before Brexit. But I can't find it for sale at the moment. It has definately gone in and out of availability many times of the years.

I don't think it is critical to get that exact kit. Many skilled microscopists have had good sucess using various brands of oils and greases, and I am sure that there will be something available to you that will work just fine. Something like an oil for sewing machines or watches should probably work fine.

[apochronaut]

Shaver oil. it has a thin nozzle for application to seams and the like. The last time I looked into the Nye Hobby kits, they had been discontinued but a phone call to Nye located 7 at a distributor. I use that oil a lot but as Victor says, other light oils will do, or might do.
The problem with collars is that there has to be a physical connection between the mechanical parts and the optical parts, so oil can creep into the lens housing.
I have done quite a few repairs by introducing oil from the outside and recommended the same to others but in some cases they have fouled the lenses by going overboard with the oil. Any oil you use must not gass off. I would be worried about some lighter oils.
My rule of thumb is if you put 3 drops of oil in the seams and there is no movement then it is a disassembly job.
Presumably that screw shaft is the correct size if the head isn't. However if that locking screw hole has been drilled and tapped for a larger screw, a large head like that could allow for higher torque on the screw and possibly deform what are fairly malleable brass structural components. Maybe that screw is binding something? It is just a locking screw on a collar but if it was too long?

[karhukainen]

Shaver oil. it has a thin nozzle for application to seams and the like. The last time I looked into the Nye Hobby kits, they had been discontinued but a phone call to Nye located 7 at a distributor. I use that oil a lot but as Victor says, other light oils will do, or might do.
The problem with collars is that there has to be a physical connection between the mechanical parts and the optical parts, so oil can creep into the lens housing.
I have done quite a few repairs by introducing oil from the outside and recommended the same to others but in some cases they have fouled the lenses by going overboard with the oil. Any oil you use must not gass off. I would be worried about some lighter oils.
My rule of thumb is if you put 3 drops of oil in the seams and there is no movement then it is a disassembly job.
Presumably that screw shaft is the correct size if the head isn't. However if that locking screw hole has been drilled and tapped for a larger screw, a large head like that could allow for higher torque on the screw and possibly deform what are fairly malleable brass structural components. Maybe that screw is binding something? It is just a locking screw on a collar but if it was too long?

Alright, thanks. I'll try to look into it during next weekend if I can find some suitable oil before that. What would you do about the front element? I think it should retract, right?

[apochronaut]

The entire optical tube retracts as a safety precaution against both front element and slide damage.
I have seen 3 reasons for the optical tube to not retract. 1) The spring has been replaced with a solid spacer, stopping the retraction from taking place. This is a deliberate modification and usually at the factory. 2) The spring is caught on something and jammed. This usually results in a shortened objective, with the amount of extension of the lower and inner barrel, less than it should be. 3) The lower, inner barrel is jamming in it's guide, caused by either excessive physical contact or severely hardened unnecessary lubricant. There need not be any lubricant to facilitate movement.

I wonder about that replacement screw being a possible fourth cause.

[viktor j nilsson]

IMG_20231101_190207.jpg (105.77 KiB) Viewed 8906 times

Here's my 40x 0.85. It does look like your screw is not original.

[karhukainen]

Thank you viktor and apochronaut!

[karhukainen]

The entire optical tube retracts as a safety precaution against both front element and slide damage.
I have seen 3 reasons for the optical tube to not retract. 1) The spring has been replaced with a solid spacer, stopping the retraction from taking place. This is a deliberate modification and usually at the factory. 2) The spring is caught on something and jammed. This usually results in a shortened objective, with the amount of extension of the lower and inner barrel, less than it should be. 3) The lower, inner barrel is jamming in it's guide, caused by either excessive physical contact or severely hardened unnecessary lubricant. There need not be any lubricant to facilitate movement.

I wonder about that replacement screw being a possible fourth cause.

I finally had time to try to fix the objective. I couldn't get the objective to work without disassembling it and ran into a few problems. Everything is more or less unstuck, but now the "lever" that moves inside the objective stays in the upper position unless I push the front element. That is, if I want to adjust the correction collar for, let's say 0.17 mm, I need to rotate the collar to 17 and then push the front element. I can then turn the ring to 11 and it works, but if I want to go higher than 17, I got to turn the ring to what ever number I want and push again. It seems that either the lever needs some lubrication or the spring in the back of the objective isn't working. Also, some of the smallest screws were in such bad shape that they crumbled into bits.

I used a few drops of xylene (added from outside the objective) to get the correction collar unstuck and then removed all the housing parts. I also accidentally turned the inner element and had to use circlip pliers to open the back of the objective so that I could return it into its correct position. I cleaned hardened lubricants from the threads and applied some sewing machine oil. The collar now turns smoothly and the front element also moves easily. I don't think the big replacement screw was causing any of the problems. Any ideas what to do with the lever issue or where to get new screws? (Before anyone asks, no, unfortunately I didn't manage to take any helpful photos even though intended to.)