Repairing/Replacing Tiny Metal Part

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J_WISC
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Repairing/Replacing Tiny Metal Part

#1 Post by J_WISC » Thu Aug 11, 2022 1:25 am

So, I broke this tiny metal part -- inside the nosepiece -- that aligns the tube and objective lens as it's rotated into place:
unnamed.jpg
unnamed.jpg (99.57 KiB) Viewed 2712 times
Does anyone have advice or suggestions regarding repairing or replacing it? I think it's steel, very brittle steel. I found the same nosepiece online, but sort of expensive just to get a part. More expensive than the cost of the microscope! On the other hand, it would probably be even more expensive to take it to a local parts fabricator. I know someone who makes jewelry, but she won't touch it. Could soldering work? The microscope is still fine. I could just mark the position of each objective. But it is just annoying, the only part not correctly working.

(There will be no further discussion of how I did this. I will not let this happen again. New people ... NEVER try to force something to move.)

Scarodactyl
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Re: Repairing/Replacing Tiny Metal Part

#2 Post by Scarodactyl » Thu Aug 11, 2022 1:55 am

You could probably make a crude but effective replacement with spring steel using a vise, pliers, hacksaw and a drill press.

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woyjwjl
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Re: Repairing/Replacing Tiny Metal Part

#3 Post by woyjwjl » Thu Aug 11, 2022 2:36 am

I'll try this first: casting glue.
O1CN01llzUhQ1plFVRVbB3p_!!2152735400.jpg
O1CN01llzUhQ1plFVRVbB3p_!!2152735400.jpg (112.82 KiB) Viewed 2691 times
It doesn't involve advertising. I've used this one before, and it works well.
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Hobbyst46
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Re: Repairing/Replacing Tiny Metal Part

#4 Post by Hobbyst46 » Thu Aug 11, 2022 6:55 am

If the broken part is made of cast iron it would be difficult to repair by welding.
Otherwise, silver welding might work. I doubt that epoxy or other glue will keep it sturdy for its job.
If nothing else seems practical, I would find or buy a brass plate of the appropriate dimensions - and with hand tools (a vise would be a must) and drill press, create a copy of that part. It is doable, although very time consuming.

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imkap
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Re: Repairing/Replacing Tiny Metal Part

#5 Post by imkap » Thu Aug 11, 2022 7:44 am

I think glue might work too, just buy a buy the right type. Making holes in both separated parts and inserting 2 rods might help strengthen the connection.

Finelld
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Re: Repairing/Replacing Tiny Metal Part

#6 Post by Finelld » Thu Aug 11, 2022 8:06 am

It should be made from spring steel. Looking at your pictures it appears that there was a fault in its manufacture. I don’t know what resources you have or have access to. You could take a piece of sheet spring steel, heat it so it can be formed to the right angle shown in the photos. After it is bent cut it to the right shape and dimensions. Then it will need to be re-tempered. The only type of repair that I can think of that might work is micro welding but you will still need to remember the part afterwards. You might also call some microscope repair shops. Older ones often have a stash of old microscopes and parts that they can cannibalize from. You can also try the manufacturer if you can get them to respond.

GerryR
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Re: Repairing/Replacing Tiny Metal Part

#7 Post by GerryR » Thu Aug 11, 2022 11:17 am

That can be brazed. Because of the minimal amount of deflection required of the part, most any material can be used for the part. If you can't find anyone to braze it for you, you are welcome to send it to me and I'll braze it, and perhaps make you a new replacement for just shipping costs. I make replacement gun parts all the time (gunsmith), and I'm a mostly retired automation engineer with a small machine shop. Happy to help out. I'm in VA. PM me if I can be of service and I'll send you my shipping address.

apochronaut
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Re: Repairing/Replacing Tiny Metal Part

#8 Post by apochronaut » Thu Aug 11, 2022 12:11 pm

The part isn't that tiny. Almost 3cm. Let us know what model it is from. Someone may have the part.
It looks to be a stamping

To make a replacement. Hardware stores, Walmart etc. usually sell cheap paring knives, the kind with the bird beak blade that many people use for peeling. They are a quite thin flat stainless blade set in a plastic handle, made in Pakistan or farther east somewhere. You should be able to find one for about 4.00. The stainless has a fair degree of temper and spring and the blade portion is about 2 1/2" long. There is enough depth in the blade at the hilt to make a facsimile of the bracket section of your part. The blade has a curve to the tip similar to your part. The tip can be flattened on an anvil or vice into the desired width and indented with a cold chisel to make the detente point. The body of the blade forward of the bracket section can then be initially reduced with a grinder but finished with a file to give the desired amount of reflex. I would think that you will have to leave more material in the arc of the knife blade than in the original part in order to compensate for the difference in the spring of the material, plus the fact that the knife blade is thinner. If you do everything cold, most of the original hardness and spring should remain. Any bird beak knife blade will do. Those cheapos are easy to find, though. A thicker blade is probably better.

That part can be repaired. Any competent welder with a small oxy acetylene tip in the zeroes could braze that with only localized loss of temper. The loss of temper is accomodated for by building up the bronze into a broad arc on both sides of the piece to strengthen the detempered area. Silver solder would work even better. I had an ancient wooden faced driver once that had a silver soldered shaft where the former owner had deliberately bent it and broken it, right in the middle. I found it in a garbage can, had it silver soldered back together and it performed like a charmed club for years until I sold it when I stopped playing golf.
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Scarodactyl
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Re: Repairing/Replacing Tiny Metal Part

#9 Post by Scarodactyl » Thu Aug 11, 2022 12:52 pm

apochronaut wrote:
Thu Aug 11, 2022 12:11 pm
It performed like a charmed club for years until I sold it when I stopped playing golf.
Of course it did, it knew what might happen if it didn't :D

apochronaut
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Re: Repairing/Replacing Tiny Metal Part

#10 Post by apochronaut » Thu Aug 11, 2022 2:50 pm

The welder that did it was a former aircraft welder that worked at the plant my dad worked at during the 60's. He did it on his lunch break. I'm not sure such free service of that degree exists in today's world . Some places I guess.

After that I became enamored with silver solder and when I got involved with the processing of food about 15 years later I bought a 1 lb. roll of food grade silver solder and it's acid flux which I think is muriatic acid. Even the food grade stuff has a high tensile strength, about double that of tin/lead solder. It was 60.00 a roll in 1982. I still have about 1/4 lb.. A little goes much farther than tin lead solder.

There are many alloys of silver solder. The food grade version is soft and malleable on a roll like plumbing solder and can be melted with an iron. The stuff used for welding in a similar fashion to brazing needs a torch, although it melts at a much lower temperature than bronze, allowing protection from over heating of thin materials. Surprisingly and that welder obviously knew his stuff, certain alloys of silver solder have a higher tensile strength than bronze welding ; around 60 or 70,000 p.s.i.., so that was the best choice.
Any other questions Mr. Dactyl?
.

J_WISC
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Re: Repairing/Replacing Tiny Metal Part

#11 Post by J_WISC » Thu Aug 11, 2022 3:59 pm

Once again, THANKS! You're all an impressive collection of knowledge and skills. I'll try to solve this locally. I like the suggestion of going to a gunsmith for parts like this. I did not think of this. And I'm pretty sure there are several gunsmiths nearby. Also, the improvised crafted substitute doesn't sound too challenging. I'm not exactly mechanically inclined, but the detailed instructions give me some confidence this shouldn't be too difficult for me. I doubt this is the last time I'm going to have to improvise something; I'm better at breaking than fixing things.

Oh ... I agree it is a small part, not a tiny part.

EDIT: On closer inspection, I see it is probably cast metal.

PeteM
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Re: Repairing/Replacing Tiny Metal Part

#12 Post by PeteM » Thu Aug 11, 2022 6:09 pm

Along the lines of early suggestions, I think you could make this yourself out of a short strip of spring steel. Looks like a piece about 3/4" by 3" long could do it. Temper the very ends with a propane torch to soften the steel, while wrapping the center with wet cloth to keep it relatively cool. Cut/grind it to shape, then bend and drill the angled end -- and then form the notch end - leaving springy steel in between. Grind edges to clean things up.

Someone might have a spare nosepiece - wouldn't hurt to know the make and model of your scope.

Depending on your scope you might also replace this part with a ball spring detent, held and attached to your turret by some sort of holder.

Personally, I don't think you have enough area for an epoxy glue to reliably work.

Cast metal can be difficult depending on the composition, but TIG or braze can sometimes work.

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woyjwjl
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Re: Repairing/Replacing Tiny Metal Part

#13 Post by woyjwjl » Fri Aug 12, 2022 6:44 am

If its working conditions allow for wire to be wrapped around it (presumably a hole will need to be punched), a solution that balances reliability, convenience and economy with a castellated adhesive solution.

Glue advances beyond your resemblance ......
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Dubious
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Re: Repairing/Replacing Tiny Metal Part

#14 Post by Dubious » Fri Aug 12, 2022 3:39 pm

I second the suggestion that you identify the microscope. If this part is from a vintage microscope, is very possible that someone has an unneeded frame from which they could remove and give you that nosepiece part. I don't consider myself to be that prolific a collector of vintage parts; still, in an effort to get particular microscopes working, I've accumulated a bunch of frames from which I've harvested various parts...

Chas
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Re: Repairing/Replacing Tiny Metal Part

#15 Post by Chas » Sat Aug 13, 2022 6:04 pm

I found the same nosepiece online, but sort of expensive just to get a part. More expensive than the cost of the microscope!
I dont know if I am being a wet rag about repairing the spring, but if you can get the whole nosepeice I would go for it ...I once tried to adjust a revolving nosepiece (it had tangential screws to adjust for each objective) and rather wished that I hadnt :cry:
The way that they are attached to microscopes differs ... some are easy to remove as they simply have an RMS thread and a locking collar, others that arent too bad have an RMS threaded bush that passes through the top part and into the body with a slot cut into the face of the bottom of the bush, to allow them to be unscrewed. Unfortunately some are much more difficult.
If you do attempt to remove the whole thing; give the the joint a soak in in some penetrating liquid and leave it for some long time before trying to unscrew it.

One with a locking collar:
Locking collar.jpg
Locking collar.jpg (56.87 KiB) Viewed 2293 times
One that is removed by unscrewing the slotted thing:
Unscrewable slotted.jpg
Unscrewable slotted.jpg (97.42 KiB) Viewed 2293 times

Chas
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Re: Repairing/Replacing Tiny Metal Part

#16 Post by Chas » Sun Aug 14, 2022 1:07 pm

It occurs to me that your broken revolving nosepiece might be an opportunity ;-) :

Revolving turret nosepieces can 'get in the way' if you are trying to illuminate or diffuse the light to view something from above.

Quick-change objective holders hold just one objective but you can either remove the holder and change the objective in it, or if you have two holders, with two objective mounted in them, you can just swap them.

Here is an example (I have no idea of the make of the changer) :
Objective holder 640.jpg
Objective holder 640.jpg (109.41 KiB) Viewed 2287 times


This objective holder slides into a carrier that is attached to the end of the microscope tube (it has a male RMS thread):
Carrier for objective holder.jpg
Carrier for objective holder.jpg (87.56 KiB) Viewed 2287 times
With a changer like this you can lower the objective into something like the top from an LED light bulb, which wouldnt be easy with a revolving turret, or illuminate it as you would normally try to do.

The whole setup isnt too big, or anything:
Whole thing.jpg
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I notice that there seem to be quite a few similar looking Reichert ones often advertised in the US ..but I dont know anything about them, but I bet Apochronaut might know about them! :-)
Last edited by Chas on Sun Aug 14, 2022 3:41 pm, edited 4 times in total.

Hobbyst46
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Re: Repairing/Replacing Tiny Metal Part

#17 Post by Hobbyst46 » Sun Aug 14, 2022 1:35 pm

The objective in the photo is marked Baker, of London.
BTW decades ago, Zeiss also made such ojectives and single objective holders for epi illumination on the Standard.

Chas
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Re: Repairing/Replacing Tiny Metal Part

#18 Post by Chas » Sun Aug 14, 2022 3:37 pm

Hobbyst46, I have altered the post to make it clearer :-)
I imagine that the holders were useful to get the objectives absolutely centered on the same spot.
Last edited by Chas on Mon Aug 15, 2022 9:09 pm, edited 1 time in total.

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