MicrobeHunter.com Microscopy Forum

Merry Christmas and Happy New Year to all.

I am trying to use a Nikon Optiphot that apparently received no mechanical service since many years ago.
The coarse focusing knob requires undue effort (in my opinion) to rotate and set focus.
I have downloaded a 35-page pamphlet titled "Nikon Optiphot/Labophot Bodey Repair Manual - The repair guide for a beginner as well as an experienced technician".
The existence of such a manual, and this specific title, raised in me a great admiration for the Nippon Kogaku manufacturers.

Yet the service that I found in the manual is based on complete disassembly of the mechanism, needs special tools etc and I am willing to try a shortcut.

Does anyone know a simple way to ease the tension on the coarse focusing knob?

Thanks in advance for ideas.

There are many on this forum more qualified than I in terms of disassembling stands and rebuilding them. I can give you some advice, albeit disassembly is generally the best.


First some Nikons have the option to tighten the coarse focus rack using a dial/knob between the coarse focus and the stand on one side. Does the Optiphot have such as dial/knob?

If it does you turn that to control the stiffness of the coarse knob. If not, assuming the coarse focus knob is difficult to move due to hardening of the grease over time, you can use a small amount of penetrating oil applied to the gear track upon which the stage rides. Then move the stage up and down slowly so as to not break anything. I do not recall if the Nikon Optiphot has any plastic in the gear train. Penetrating oil is not the preferred material for lubrication because alone it does not provide sufficient friction nor longevity for the focus rack. However when applied in small amounts to a rack with hardening grease it can serve to loosen up the rack while maintaining sufficient friction to prevent unwanted slippage. It is an alternative to dissembling.

Once other forum members see this post I am sure other Nikon owners will chime in.

Happy Holidays!

If you have already adjusted its tension control wheel (located between coarse wheel and stand) and it does not work, I would suggest spraying some WD40 and let it sit for a day or two.

If that does not work, you may have to take it apart to clean and lubricate the inside.

Please do not force the focus wheels or turn them against each other. There are plastic parts inside that can be broken.

Thanks a lot, einman and zzffnn, for your advices. Will attempt to follow them very soon.

Merry Christmas, everyone.

Hobbyst46, unfortunately there are no suitable shortcuts for the proper lubrication of the focusing mechanism. I agree with zzffnn that the knobs should not be counter-rotated, but disagree about the WD-40. I would suggest never spraying that stuff anywhere on or around a microscope. There are no points where the lubricant from such an application could reach that would have any effect on the problem. The focusing tension is factory adjusted and your problems are due to neglect. A complete disassembly is the best way to do the job. If you ever use WD-40 I suggest using it as a solvent to remove old lubricant where it is applied specifically to the point of concern and then cleaned. Use the proper lubricant to complete the job.

You have a very nice microscope.

All the best in your endeavors.

lorez

Thanks, Lorez.

WD-40 is extremely useful against rust - iron oxides, frozen steel joints etc. But I have used it to loosen up the condenser and condenser rack of my Zeiss GFL, which are made of brass, and it helped. I also used it on this Nikon Optiphot. It is a trinocular scope, and the eyepiece/camera selector handle in the trino head was frozen (certainly due to long-term negligence). I could not pull it out to switch from the eyepiece view to the combined camera/eyepiece position.
So I sprayed VERY LITTLE WD-40 onto the track grooves inside - not on the prism, wiped it clean after 10 minutes, applied the same pulling force as before, and the handle came nicely out and now it moves freely as it should.

So, I will very very carefully inspect every niche around the focusing mechanism to see if and where the penetrating WD-40 can be applied, very carefully apply it step by step. I hope to avoid the complete overhaul...

Yes, I was aware of the bad reputation WD-40 has and that was why I recommended a "penetrating oil". Stepped over that mine!! LOL

einman wrote:Yes, I was aware of the bad reputation WD-40 has and that was why I recommended a "penetrating oil". Stepped over that mine!! LOL

Agreed 100%

My preferred penetrating oil is PlusGas Formula A
... use the liquid, not the aerosol can, and apply locally.
It seems to successfully 'thin' the hardened grease.

MichaelG.

Merry Christmas to you all!

Hobbyst46, you might think about this: Normaly everything gums up in the same speed. Due to the gear ratio one often don't recognise it in the fine focus movement immediately. When you bodge your coarse focus to work halfway good you might wreck you fine focus later because there is too much load on the gearing. Problematic is every resistance behind the fine focus gears, so mainly the stage guides. A fine focus axle that moves a bit slow in its bearings is less of a problem. Especially bad are gummed up dovetail guides for the stage. A roller bearing stage is a little less critical.
From my experience there is no way to revive old gummed up grease. It is possible to free it up a for a while but it goes bad again when the solvents evaporate.

So if this is a stand you like and want to use for longer, I would recommend the complete overhaul. It is nice to have some special instrument grease available. They contain animal fats and stick to the surfaces much better.

Bob

My bad for mentioning WD-40, sorry. It is surely not the proper way used by pros. Nikon did list (different) specific lubricants and glues to use for specific parts.

When my Optiphot's focus mechanism broke, I did take it apart and replace some parts inside. It was actually easy, following instructions from the service manual. So don't fear for (or be too lazy to do) a complete disassembly and cleaning.