Old microscope stuck

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dechrlam
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Joined: Wed Mar 13, 2019 4:46 am

Old microscope stuck

#1 Post by dechrlam » Wed Mar 13, 2019 5:22 am

I recently purchase a used Eschenbach Elementar Plus 34221. It has the same optics as a Kolleg SH45.

Despite being listed as functioning, the stage does not move - I supect the lubircant is too old and is dried / gummed up.
I removed all screws possible and tried lots of penetrating spray - Caramba Rostlöser. This did not help at all.

The coarse focus gears and toothed track look fine and engage(Nobody forced and broke them yet)
The fine focus knobs turn, but do not do anything. Perhaps they are broken.

What can I do to dissolve the old lubricant?
Brake cleaner or petrol bath?
I don't care about dissolving the painted finish. I want to spray it pink anyway for my daughter.

Thanks for any suggestions

Hobbyst46
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Re: Old microscope stuck

#2 Post by Hobbyst46 » Wed Mar 13, 2019 9:40 am

Welcome!
Looks like your microscope is a locally branded Motic or similar microscope. Please correct if I am wrong.
Pictures, especially of the faulty parts, will help others to try to identify the problem.
Suggestions:
1. I somewhat doubt that grease hardened, since the microscope is proabably not very old.
2. Even if the grease hardened, since the knob rotates, there is no excessive friction on the knob; rather, perhaps a broken gear part, or it has run off the track (beyond the stop).
3. A solvent bath is definitely not recommended (unless you isolated a very small part that is visibly coated with grease!). Hardened grease should be removed locally, using moistened Q-tips, or small pieces of tissue paper (Kim Wipes are best) held with twizzers. Or pushed around with a watchmakers screwdriver. Flooding with solvent will not help.
4. Hardened grease can be softened with liquid hydrocarbons, such as light petrol (95-98 octane), octane, heptane, or similar. Their only weak point is flammability. Other common solvents are less powerful. BUT, do not expect rapid dissolution. The grease can be softened, some of it will dissolve, but wiping with tissue (see above) works best. use sparingly, do not let the solvents reach the optics.
5. Gentle local heating soetimes helps to free frozen parts, but if the gear is made of plastic, heating may damage it.
Also, never heat it unless it is dry and free of any solvent.
6. On the rare and unlikely possibility that the parts are stuck due to any type of glue, acetone might help to dissove it, but again, not a bath, no flooding, just local careful application.
7. Bear with me for suggesting to avoid painting the microscope pink. For convenient use, a more neutral background, that does not distract the eyes, and not too bright, is better IMHO. For grown ups and children alike.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

dechrlam
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Joined: Wed Mar 13, 2019 4:46 am

Re: Old microscope stuck

#3 Post by dechrlam » Wed Mar 13, 2019 11:26 am

Hi Hobbyst46,

Thanks for the suggestions. I will get some good quality pictures up this evening European Time.

Not sure about branding, but it does look a lot like a Motic F-11. The moulds for production are probably the same. The arrangement Body > Coarse Focus > Block > Fine Focus > Stage is exactly the same.
The coarse focus wheel moves a block. The fine focus is attached to this block and this moves the stage.

1. I will try to find a year
2. The gear rod(stainless steel) appears to be engaged with a brass toothed rail. The knobs do rotate about 5 degrees back and forward, but when they try to move the rail, they slip. It takes a strong twist of the knob before they slip.
4. I removed all the optics, but I will wait for more suggestions before a solvent bath. I still need to remove the coarse focus wheels and the gear rod. Have to make a tool for this first. When this is done I can apply a lot of force if needed.
5. I tried the oven at 70C / 158F for 30 Minutes with repeated sprays of penetrating oil in the gaps of the dovetails connecting the blocks and all the gaps I could find.
6. I will look for signs of glue
7. OK I think no pink after all!!

Before I do anything, I will post some good quality pictures.

MicroBob
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Joined: Sun Dec 25, 2016 9:11 am

Re: Old microscope stuck

#4 Post by MicroBob » Wed Mar 13, 2019 7:27 pm

Hi,
many years ago I had a similar microscope apart. I try to remember: The fine adjustment was done via a some kind of spiral gear on one side and I think there was a ceramic ball in there (not quite sure). I doubt that this is hardened grease, probably the mechanism is blocked or broken. I can't remember any difficulties to take it apart so this should be not too difficult. I would suggest to remove all optical components and take it apart in a bowl so nothing can get away. I remeber it as an ok microscope so it is worth to try a repair. If you have just bought it and have a way to give it back I would do this.

With which name can we adress you?

Bob

dechrlam
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Re: Old microscope stuck

#5 Post by dechrlam » Wed Mar 13, 2019 7:44 pm

The instruction manual say 5/94 Printed in Germany so the scope is probably from 1994


Image
^ Coarse and fine focus

ImageImage
^ I already put loads of penetrating oil spray in the dovetails
Image
^The fine focus moves left and right when it is twisted multiple times. It feels smooth, but the stage does not move.
Image
I need to make a tool to remove the coarse focus knobs - then remove them and the rod with the teeth. Only then can I force it with a vice or something
Image
^ I might just also try to remove the fine focus too, check for plastic and give it a bath in petrol before going to town on it in the vice.

Cheers,
Chris (who is too lazy to remove the EXIF Data from his pics)

MicroBob
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Re: Old microscope stuck

#6 Post by MicroBob » Wed Mar 13, 2019 8:06 pm

Hi Chris,
I'm sorry, but the microscope I had apart looked similar but had a different mechanism. When you say the fine focus shaft moves left and right the shapf may carry a cone on the middle section that lifts the stage as the shaft moves sideways.
Before appying too much force I would try it with heat. 60°C should be safe when the optical components are removed. This makes hardened grese softer.
One cause for stuck focus mechanisms are bits of cover slip that fell into the wrong place. Here a lot of compressed air might help (safety glasses).

Bob

Hobbyst46
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Re: Old microscope stuck

#7 Post by Hobbyst46 » Wed Mar 13, 2019 8:16 pm

Thanks for uploading these photos. They clarify the status, previously I thought that the problem lies within the X-Y movement of the stage. Now I see that you have removed the base plate from the arm, and the problem is within the focusing mechanism, fine focus rack and pinion or gear rod.
I would gently push the rack block, that is the stage carrier, left or right, along its track, to see if it again re-engages with the shaft pinion. Perhaps the range of fine focus movement is limited and the rack has now crossed the limit and out of the permissible range.
Sorry that I have no smarter answer.
To add to Bob's answer: avoid excessive force. Brass and aluminum are easily deformed or bent under pressure.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

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iconoclastica
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Re: Old microscope stuck

#8 Post by iconoclastica » Fri Mar 15, 2019 5:38 pm

From the outside, this looks like the same mechanism that Euromex used in that period (and perhaps still does). The fine focus block moves the stage, the coarse focus block moves the fine focus block, and with that the stage. The coarse focus drives a rack and pinion (I believe that are the English words for it). The fine focus just turn around and have a nut inside that moves from side to side slowly when the threaded axis turns. The nut moves with it a near vertical lever from the left to the right, and, invisible without breaking it down further than I have done, the stage up and down. It is a quite clever design that I later used to build a motorized stage for the stereo microscope.

Anyway, when the fine focus knobs themselves move sideways, the nut will stay in place and the stage won't move. It takes more force to move the lever than the whole axis, either of which may cause your trouble. I still have that Euromex on the shelf, so perhaps I could have a look again tonight to bring back the details that have sifted through my memory. But first I have to make space on my desk again, for I just finished debugging the electronix of the optiphot (broken mosfet).

Wim

PeteM
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Re: Old microscope stuck

#9 Post by PeteM » Fri Mar 15, 2019 8:03 pm

With respect to solvents, I suggest starting with a squirt bottle of Ronsonol lighter fluid. It is widely available, easy to dispense, effective on most petroleum-based greases, and safer to breath and use than something like brake cleaner. Contains "naphtha" which apparently isn't so much a specific formulation but a variety of relatively light distillates.

Stiff brushes and foam swabs can help remove the crud once you've softened it.

There are more effective solvents, but with lower flash points, breathing risks, and greater potential for damaging cements and plastics.

Both brake and carburetor cleaners contain a mix of more aggressive solvents, but with greater risks.

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iconoclastica
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Re: Old microscope stuck

#10 Post by iconoclastica » Fri Mar 15, 2019 8:36 pm

First a correction: I said the axis and knobs stay in place and the nut moves. They don't. The whole axis is moving sideways (just like you observed) and the nut is a disk fixed to the axis that pushes the lever to the right. The lever directly lifts the stage, which comes down (by gravity I presume) when relaxed. I can easlily push the lever to the right with a screwdriver.

-----
EDIT: the stage returns not by gravity alone; it's spring loaded. If the stage is free (not stuck), and the fine focus has been turned to the left, it should be possible to pull it upward and let go.
-----

This it how it looks like on my old study scope:
lateral view
lateral view
_WDW7766.jpg (75.85 KiB) Viewed 2800 times
I could turn one of the knobs off with the tips of bent tweezers
I could turn one of the knobs off with the tips of bent tweezers
_WDW7771.jpg (70.37 KiB) Viewed 2800 times
end of the axis, projecting from the flange
end of the axis, projecting from the flange
_WDW7772.jpg (72.78 KiB) Viewed 2800 times
flange removed too, the disk on the axis is clearly visible, the lever is at the right in front of it (arrow)
flange removed too, the disk on the axis is clearly visible, the lever is at the right in front of it (arrow)
_WDW7776.jpg (43.59 KiB) Viewed 2800 times
the whole axis removed
the whole axis removed
_WDW7777.jpg (63.08 KiB) Viewed 2800 times

dechrlam
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Re: Old microscope stuck

#11 Post by dechrlam » Sun Mar 17, 2019 7:33 pm

Hi Guys thanks for the great advice. I further disassembled the microscope removing the fine focus knobs and the coarse focus knobs.
The fine focus does indeed have the lever that freely moves left and right.

The coarse focus knob had a wavy shaped washer behind it which prevents 200 pound gorillas from stripping the rack and the pinion. Apply too much pressure and it slips.
I could twist and pull the coarse focus knob to disengage the rack from the pinion. A good sign that the rack and pinion are ok.
As for the fine focus, I hope it is ok. It looks like it is stuck in the topmost position. I will hopefully see tomorrow night after I get the lighter fluid bath going.

I also managed to persuade the block to move up a centimetre by whacking it with the handle of a screwdriver. So it is not a glue problem.

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iconoclastica
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Re: Old microscope stuck

#12 Post by iconoclastica » Sun Mar 17, 2019 9:06 pm

I also managed to persuade the block to move up a centimetre by whacking it with the handle of a screwdriver.
I can see you are a true fine-mechanic! :D :D :D

dechrlam
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Re: Old microscope stuck

#13 Post by dechrlam » Wed Mar 27, 2019 8:46 pm

Quick update - the coarse focus is freed up and the microscope is a big hit with my daughter
The fine focus is now in a bath of lighter fluid.

I removed the 40x objective because it is possible to crash it into the slide on the stage and it is too difficult for a child to focus using 400x and only coarse focus.
Strange as the manual mentions them being parfocal. I removed the prism when the microscope went into the oven for warming.
Maybe I will have to align or collimate it. Not sure how to do that, but that's for another day after the fine focus is freed.

mnmyco
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Re: Old microscope stuck

#14 Post by mnmyco » Wed Mar 27, 2019 10:21 pm

I had to resort to engine degreaser (basically diesel fuel) to remove the hardened crap on an ortholux.

dechrlam
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Re: Old microscope stuck

#15 Post by dechrlam » Fri Mar 29, 2019 4:20 am

Last update - the fine focus is freed now and the microscope is working quite nicely.
Penetrating sprays and immersion in lighter fluid was a total waste of time.
The only thing that helped was hammering in a improvised jig to protect the soft zinc or aluminium blocks.
It looks like someone "serviced" the blocks some time in the past and just used some wd40 and over tightened the dovetails.
This resulted in a dried grey powder/paste (from block friction) binding the blocks together.

For anyone not getting anywhere with stuck parts and running out of options and only left with the hammer option - build a jig out of wood to hold the parts then hit it with using another piece of wood to protect the soft metal from deformation from the hammer blows. Any deformation on the sliding surfaces can be removed with sandpaper.

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iconoclastica
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Re: Old microscope stuck

#16 Post by iconoclastica » Fri Mar 29, 2019 9:37 am

Sorry I am too late :D

Congratulations, your efforts have been rewarded!



(The plate unscrewed indeed releases the fine focus block. It shifts upwards until it hits the arm:)

_WDW7831.jpg
_WDW7831.jpg (109.06 KiB) Viewed 2323 times
_WDW7830.jpg
_WDW7830.jpg (100 KiB) Viewed 2323 times

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