Leitz Orthoplan - How to adjust focus tension?

[davidf99]

I have a Leitz Orthoplan in very good condition. The fine adjustment turns easily, but the coarse adjustment is too still. It turns, but almost needs too hands to turn it.

I would like to lession the knob tension, but there is no tension control on this scope. I have read that for some scopes the tension can be adjusted by turning the right and left knobs in opposite directions. That doesn't seem to work with my Orthoplan. Maybe because it's too tight to turn that way? I don't want to force it and maybe break something inside.

Anybody have a suggestion? I do not want to have to open up or disassemble the focus mechanism. There doesn't seem to be an easy way to get lubricant inside since all the fittings are very tight, and I wouldn't know what kind of lubricants to use. Any advice would be greatly appreciated.

[davidf99]

I'm resending this question because I can't live with all the typos in my first version

I have a Leitz Orthoplan in very good condition. The fine adjustment turns easily, but the coarse adjustment is too stiff. It turns, but almost needs two hands to turn it.

I would like to reduce the knob tension, but there is no tension control on this scope. I have read that for some scopes the tension can be adjusted by turning the right and left knobs in opposite directions. That doesn't seem to work with my Orthoplan. Maybe because it's too tight to turn that way? I don't want to force it and maybe break something inside.

Anybody have a suggestion? I do not want to have to open up or disassemble the focus mechanism. There doesn't seem to be an easy way to get lubricant inside since all the fittings are very tight, and I wouldn't know what kind of lubricants to use. Any advice would be greatly appreciated.

[zzffnn]

Welcome to the forum, David.

You are right in being cautious. Turning the focus knobs in opposite directions will break focus gears for Nikon Labphots and Optiphots. So please wait for an owner to comment.

Sometimes it can be old lubricating grease that solidified and froze the focus drive. If that is the case, carefully instilling some mineral spirits around spaces around the focus drive may help freeing it.

Xylene works the same way and solubilize grease faster, but it is a harsher and toxic chemical.

[Alexander]

This is hardened grease for sure. There is only one way to fix it: disassemble, remove the old grease, re-grease, assemble. The Orthoplan does NOT have the feature to vary the tension by turning the knobs in opposite directions. Both knobs should turn very easily if in proper condition.

This jobs is not easy and requires specific knowledge and skills.

[zzffnn]

Try pouring a tiny amount of mineral spirits around the focus knob, David. You may get lucky.

[Leitzcycler]

Try pouring a tiny amount of mineral spirits around the focus knob, David. You may get lucky.

I don't think it will penetrate inside. In the similar situation I would probably take the focusing block out of the stand and add some lubricant e.g. WD40 into the coarse focusing parts. This might work for first aid. Putting the block back needs realigning. There is a thread about focusing block disassembly and realigning somewhere here.

There are focus blocks in Ebay from time to time. I would probably buy one, change it and then try to disasssemble and relubricate the old one. Just in case it would take a huge amount of time and I would most likely to ruin it anyway.

[zzffnn]

Gents, I don’t disagree with you on what is the best action in experienced hands. For a beginner microscopist though, opening up the focus drive may be intimidating.

I have released an AO scope focus drive by carefully pipetting mineral spirits into tiny spaces around the focus knob, without disassembling anything. But I realized Leitz scopes may be very different. That was why I said “try…….you may get lucky”. There is nothing to lose by following my suggestion, if one is careful.

[TonyT]

I had the same, actually worse, problem with my recently-purchased Ortholux; looks like same focus block as the Orthoplan.
A long blast of warm air from my wife's hair dryer (warm setting, not hot!) until the knob felt warm did the trick.
Still a little stiff to turn but before treatment it would not turn at all.

[BramHuntingNematodes]

If you have any Hammond organ oil that stuff will work its way through any tiny gaps and wick into crevices, loosening hardened grease. Sewing machine oil also works pretty good-- would not recommend 3-in-1 as it gums up.

[Alexander]

I had the same, actually worse, problem with my recently-purchased Ortholux; looks like same focus block as the Orthoplan.
A long blast of warm air from my wife's hair dryer (warm setting, not hot!) until the knob felt warm did the trick.
Still a little stiff to turn but before treatment it would not turn at all.

Turning the knobs on a Ortholux or Orthoplan with hardened grease may damage the focus block. I strongly recommend to do a proper service to restore the focus block.

[davidf99]

I tried TonyT's approach, with a low-powered heat gun, the kind used for arts & crafts.

Focused mild heat on the coarse adjustment knobs on both sides until they felt warm.

It worked! The knobs are now noticeably easier to turn.

Still a little stiffer than I like, but I don't need two hands to turn the knobs.

I don't know whether mineral spirits or sewing machine oil can get inside, but I'll try that also.

[zzffnn]

Xylene is more effective in dissolving solidified grease. If you only buy one solvent, buy xylene. It is a bit toxic though, so try not to breath it in.

[Leitzcycler]

We are talking about oil only if you have the focus block opened. There is no way to get oil inside Orthoplan focus block without taking it off the stand. This may, in turn, lead to collimation problems. Xylene is only used when the focus block is completely serviced. That means all the parts will be removed, hardened grease removed and then relubricated and reassembled. However, mineral spirit will be more safe.

Orthoplan focus block is very difficult to service. See here: https://www.microbehunter.com/microscop ... 815#p93429

If you can live with warming it, don't use xylene (or oil). Two hands to turn: you most probably ruin the focus mecahnism.

[davidf99]

My first try with the heat gun helped a lot, but coarse focus was still stiffer than I like.

Today I removed the stage, which gave me some access to the inside of the focus block. Not complete access, but enough for mineral spirits to wick inside. I put a knapkin under the area to catch any mineral spirits that might drip down (none did). Using an eye dropper, I got the mineral spirits into the area where the ball bearings are, even though I couldn't see inside. Also applied some around the edges of the big knobs on both sides.

The results were great. The coarse adjustment is now smooth as butter. The only question is whether it will last.

Next issue is a stuck iris in the bottom of the frame. If it were stuck open I might let it go, but it's stuck closed. I should be able to unstick it when I figure out how to get to it without a hacksaw. Probably the easiest way would be to turn the frame upside down and remove the bottom, but I'd have to remove everything, and it'll still be heavy to manipulate. So I'll try to rig up some kind of L-shaped tool to reach the iris. Don't know if it is the iris itself that's stuck, or the knob that opens and closes it.

This Orthoplan might have been sitting in storage unused for years or even decades before I got it.

[imkap]

My first try with the heat gun helped a lot, but coarse focus was still stiffer than I like.

Today I removed the stage, which gave me some access to the inside of the focus block. Not complete access, but enough for mineral spirits to wick inside. I put a knapkin under the area to catch any mineral spirits that might drip down (none did). Using an eye dropper, I got the mineral spirits into the area where the ball bearings are, even though I couldn't see inside. Also applied some around the edges of the big knobs on both sides.

The results were great. The coarse adjustment is now smooth as butter. The only question is whether it will last.

Next issue is a stuck iris in the bottom of the frame. If it were stuck open I might let it go, but it's stuck closed. I should be able to unstick it when I figure out how to get to it without a hacksaw. Probably the easiest way would be to turn the frame upside down and remove the bottom, but I'd have to remove everything, and it'll still be heavy to manipulate. So I'll try to rig up some kind of L-shaped tool to reach the iris. Don't know if it is the iris itself that's stuck, or the knob that opens and closes it.

This Orthoplan might have been sitting in storage unused for years or even decades before I got it.

Iris can break if forced so be careful. I'd say the best bet is to disassemble, clean and put back. It shouldn't be hard, just fiddly. Careful not to bend the leaves.

[Hobbyst46]

Congratulations on solving the focusing problem of the Orthoplan ! relative to that, most other mechanic issues are easy. You really found the best way around.
Unfortunately there is no "generic" solution to such problems. The severity of the problem differs from one scope to another.

About the stuck iris: the iris leaves are often stuck to each other due to hardened grease or oil or other junk from the past. The handle is not the problem.
Iris leaves are supposed to be very clean and DRY! not oiled, not greased.

Cleaning iris leaves:
1) Quick and dirty job: without disassembly, dip a Q-tip into heptane or octane or lighter fluid or petrol ether and wipe the visible part of the leaves as much as possible.
Apply the liquid freely, do not spare. Try to gently open/close the iris. Repeat for several times. Even inject a drop or two into the leaves retaining ring. If it works, change the Q-tip and wipe dry. This procedure is often sufficient.
2) Thorough cleaning: complete disassembly, separation of the leaves outside the iris port and individual cleaning and drying. Reassembly is not easy but it is less intimidationg than its look. There are some old threads on the forums where it is described on other microscopes.

[davidf99]

I couldn't see a way to remove the iris assembly from the base, at least not with the frame right-side up. Maybe if I turned the frame upside down and removed the bottom plate. But I'd have to strip everything off the frame, and it still would be heavy to turn over.

Therefore, I took the easy way out. Using an eyedropper, I applied a small amount of mineral spirits to the iris leaves. A little pressure on the thumb wheel and suddenly the iris turned easily. Can now open and close it with no effort at all.

**************************************************************************************************

Almost there with loosening stuck parts. Next issue is the left-right movement of the slide-holder. The problem is that the metal bar "runner" that runs left-right across the top rear of the stage is stuck in the middle position. A knob under the stage is supposed to control the movement, but it won't budge. Pretty sure the problem is the bar itself. I tried wicking in mineral spirits. No luck. I tried some liquid that's supposed to free up frozen nuts. No luck. The forward-back movement of the stage works fine. The two pieces that actually hold a slide move easily by hand, and I removed them while working on the stuck runner.

I have not yet tried unscrewing the under-stage knob. That seems like a last resort, but maybe it would let me get mineral spirits inside the left-right "runner" better.

Any ideas. I hate to spend money on a new stage for such a small problem.

Orthoplan stage.jpg (74.07 KiB) Viewed 3222 times

[Alexander]

Put it in your wife's kitchen oven at 140° F (60° C) for an hour or so.

[davidf99]

I just want to get it to slide, not cook and eat it.

I don't know if the problem is dried up lubricant, a slight warp in the runner, or some kind of metal-to-metal molecular adhesion.

Instead of baking the entire stage in the oven, I'll try applying my heat gun to the runner area and see what happens.

Worst case scenario if I can't get the runner unstuck, I could link together the two sliders 3" apart, and move it left-right by hand. That would be ugly, and tough to use with high magnification, but not impossible.

[davidf99]

Thank you, Alexander. I just used my heat gun on the runner for five minutes, and it freed it right up. Now the left-right movement is smooth as butter, like the forward-back movement of the stage, and the focus coarse adjustment. Mucho gracias.

[Alexander]

Hi David,
I recommend the kitchen oven over the heat gun. The heat gun runs much hotter with much higher risk to damage things. The oven provides a lower and even temperature.

[Leitzcycler]

I recommend total disassembly, mineral spirit and toothbrush/wipes, lubrication and reassembly for the x-y stage. I have done that myself and it is not a big job. Old heated lubricant may stuck again later or does not work as it should lubricating the surfaces.

For iris diaphragm I have immersed the whole assembly into mineral spirit, mixed, changed the solvent a few times and then let the assembly to dry. There should be no oil or grease in diaphragms. It only brings problems like gets stuck and collects dust...

[Alexander]

I recommend total disassembly, mineral spirit and toothbrush/wipes, lubrication and reassembly for the x-y stage.

You are perfectly right with this. But if it is stuck disassembly might not be easy. Making the parts move eases that work.

[davidf99]

If it's the x-y stage we're talking about, I couldn't see a way to disassemble the (left-right) part that was stuck. The metal runner seems to be pressure fitted in place. Some models of this stage have screws holding the runner in place, but mine doesn't.

The reason I was reluctant to use the oven method is that I don't know how the heat might affect the black enamel coating of the stage. My heat gun (which is the lightweight version used for arts & crafts) gave more localized heat around the runner. Really it only made the area barely more than warm to the touch, and that was enough to free it up.

The only thing left to work on is the knob that controls the interpupillary distance between the two eyepieces. That's also stuck. It's not as important, because it is stuck in a position that works for my eyes, but I'll try to free it up anyway, as a matter of principle. Of course I might discover other problems later, but apart from things that were stuck, this scope seems to be in immaculate condition.

[davidf99]

Finally, my low-power heat gun freed up the knob that controls the interpupillary distance between the two eyepieces.

I had to try several times because I was afraid that too much heat might affect the glue (or whatever it is) that holds the internal lenses in the head that are under the eyepieces. Eventually I threw caution to the winds and kept the heat gun on until the adjustment mechanism got hot to the touch (not just warm), and the knob started turning, moving the eyepiece cylinders smoothly in both directions. Still a bit stiff, but that's fine because it is pretty much a one-time adjustment as long as I'm the only person using the scope. I don't expect to change the distance between my eyes very often.

Next step is to move the Orthoplan into another room where I can actually use it. It's pretty heavy and has no handles. I'll remove all the parts that come off easily (stage, head, illuminators) to lighten the weight and minimize the chance of damage.

[Hobbyst46]

Finally, my low-power heat gun freed up the knob that controls the interpupillary distance between the two eyepieces.

I had to try several times because I was afraid that too much heat might affect the glue (or whatever it is) that holds the internal lenses in the head that are under the eyepieces. Eventually I threw caution to the winds and kept the heat gun on until the adjustment mechanism got hot to the touch (not just warm), and the knob started turning, moving the eyepiece cylinders smoothly in both directions. Still a bit stiff, but that's fine because it is pretty much a one-time adjustment as long as I'm the only person using the scope. I don't expect to change the distance between my eyes very often.

Next step is to move the Orthoplan into another room where I can actually use it. It's pretty heavy and has no handles. I'll remove all the parts that come off easily (stage, head, illuminators) to lighten the weight and minimize the chance of damage.

Here is an old tip for moving the monster cheaply - place a thick polyethylene sheet under it, which will enable sliding over surfaces instead of lifting.