Broken Microscope

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sdk113
Posts: 5
Joined: Sun Mar 01, 2020 11:11 pm

Broken Microscope

#1 Post by sdk113 » Sun Mar 01, 2020 11:24 pm

Hey there guys! I was hoping someone might be able to help me out.

I own an American Optical Sixty Spencer microscope. Recently, when using it, it became "locked" in the most zoomed in position. The coarse focus knob will not move and can only be jiggled. When I took the bottom of it off to look inside, I see that a piece had popped loose. It doesn't appear broken or bent, but I'm unsure how to reattach the pieces to get it functioning again! I will add some photos/a video.

Thank you in advance!

https://youtu.be/qvf6vSYjvco

This is a link to the youtube video where I show the microscope getting stuck and the two pieces off the bottom.

apochronaut
Posts: 3546
Joined: Fri May 15, 2015 12:15 am

Re: Broken Microscope

#2 Post by apochronaut » Mon Mar 02, 2020 12:42 pm

I have not had one of those around for quite a few years but I have most of a parts manual in my possession. It looks like a simple fix, as long as you have all the pieces.

sdk113
Posts: 5
Joined: Sun Mar 01, 2020 11:11 pm

Re: Broken Microscope

#3 Post by sdk113 » Tue Mar 03, 2020 3:51 pm

apochronaut wrote:
Mon Mar 02, 2020 12:42 pm
I have not had one of those around for quite a few years but I have most of a parts manual in my possession. It looks like a simple fix, as long as you have all the pieces.
I do have all the parts. :D I couldn't find the manual online, I would be very thankful if you'd share the info in yours with me!

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Broken Microscope

#4 Post by apochronaut » Wed Mar 04, 2020 12:18 am

Haven't forgotten about you. Will dig it out in the next day and pass on the relevant pages. if I have them.

apochronaut
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Re: Broken Microscope

#5 Post by apochronaut » Wed Mar 04, 2020 3:07 pm

I have a schematic for the entire internal mechanism of your microscope. I will photograph it and post it a little later but I thought first, I would let you know that several of the parts that you show in your you tube video are not on it. It is likely that the mechanism was modified at some point. I don't know whether yours is the newer or older design. I'll just go over what you already know, just so we are on the same page.
Everything is based on that cam turning in order to move the lever assembly up or let it drop down. What is happening obviously, is that the cam is is bypassing a critical point in it's rotation, slipping over the lifter and locking against it. It is missing whatever mechanism exists to stop it's rotation.

In the schematic, the cam( part # 31, figure 5) has a pin( part 32, figure 5) screwed into it on the opposite side of it's narrowest point; that point is where the lifter settles into after the lifter falls off of the cam lobe.
This looks to be a stop pin. Is there a place for this pin on your cam? It will be located just above a screw(part 33, figure 5) that locks the cam to the fine focus nut.

In your video, there are two parts you hold that are not on the schematic. They are probably parts of a different stop system.
There is a claw and then what looks like a spring, attached to the inspection door . Are there two indents in the side of the cam, that the claw fits into? If so, the claw works to catch the cam at it's required stop and the spring holds the claw against the cam. It is possible that the spring has broken. I am guessing at the way the mechanism works but it seems likely.

Here is all the pages I have for your microscope of one similar. It's pages 21, 24,25,26,27,28 and 29 from some manual. Some of the user manuals had parts lists and exploded diagrams at the end.
Attachments
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Last edited by apochronaut on Wed Mar 04, 2020 4:36 pm, edited 2 times in total.

apochronaut
Posts: 3546
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Re: Broken Microscope

#6 Post by apochronaut » Wed Mar 04, 2020 4:28 pm

Two more pages.
Attachments
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thomas.schwarz
Posts: 121
Joined: Tue Aug 27, 2019 5:04 pm

Re: Broken Microscope

#7 Post by thomas.schwarz » Fri Mar 13, 2020 11:57 pm

Unreal that you had that doc. Where is the OP?

sdk113
Posts: 5
Joined: Sun Mar 01, 2020 11:11 pm

Re: Broken Microscope

#8 Post by sdk113 » Mon Sep 14, 2020 1:55 pm

I still have not managed to repair it, unfortunately. The manual provided shows parts that aren't there! ):

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Broken Microscope

#9 Post by apochronaut » Mon Sep 14, 2020 3:57 pm

It is a case of the design having been changed. You are missing a part : a spring. The flat bar that fits into the bottom door or plate has two little dogs bent over at the top, which engage into the focusing cam on the side. It is most likely called a cam tensioner. Those dogs provide a focus stop as well. On the other side of the bottom plate or door, your video shows a little steel ring. That is the remains of a spring that is attached to the door and then into the two reliefs cut into the middle of the cam tensioner at the other end.
The spring keeps the tensioner in place .
I'm not sure what the spring looks like. It obviously has a large loop at one end and probably a similar one at the other end to attach to the tensioner. The length would be determined by the required tension .
Maybe someone out there has a 60 with a similar design focus system and could measure the spring? Possibly a 50 would be the same.

Element 56
Posts: 268
Joined: Thu Oct 13, 2016 3:48 pm
Location: Lancaster County, PA

Re: Broken Microscope

#10 Post by Element 56 » Mon Sep 14, 2020 11:19 pm

If you're in the USA you're welcome to send it to me for repair. Unfortunately I don't have the correct spring on hand so I would have to make it or fit one that's close.

This is the correct parts diagram for your instrument. You will probably need item# 36 too which I do have.

Kirby
pg-18.jpg
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pg-19.jpg
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apochronaut
Posts: 3546
Joined: Fri May 15, 2015 12:15 am

Re: Broken Microscope

#11 Post by apochronaut » Tue Sep 15, 2020 10:21 am

Element 56 wrote:
Mon Sep 14, 2020 11:19 pm
If you're in the USA you're welcome to send it to me for repair. Unfortunately I don't have the correct spring on hand so I would have to make it or fit one that's close.

This is the correct parts diagram for your instrument. You will probably need item# 36 too which I do have.

Kirby

pg-18.jpg
pg-19.jpg
It looks like a pretty hefty spring. The ring attached to the door in the video is one of the coils. It doesn't help too much either, that the drawing of the door and spring on the schematic is pictured sideways.

Element 56
Posts: 268
Joined: Thu Oct 13, 2016 3:48 pm
Location: Lancaster County, PA

Re: Broken Microscope

#12 Post by Element 56 » Tue Sep 15, 2020 8:11 pm

[/quote]
It looks like a pretty hefty spring. The ring attached to the door in the video is one of the coils. It doesn't help too much either, that the drawing of the door and spring on the schematic is pictured sideways.
[/quote]

Some of this is slowly coming back to me. I think the spring was pretty stout and I also think I remember these are a little tricky to put back together. It no surprise AO got away from this design and went with the design you posted.

Same old story, the grease gets hard and too much stress is put on #36, the nylon "nut" as they call it. It strips or breaks and the the focus knob can now be turned past the point of no return which breaks the spring. That little scenario is going from my memory of the last one I fixed over two years ago but I think that's is what the problem was with these. I made a new "nut' out of brass to fix the one I worked on but I have since found the nylon replacements which I bought from Keck Science Center. They have no less then 50 of these older 60's in service.

The OP may want to try to contact them for a replacement spring. I think the name of the person I dealt with was Walter and he could tell you more about fixing AO model 60's than I ever could. Hopefully he's still there.

Keck Science Center
925 N. Mills Ave.
Claremont, CA 91786
https://www.kecksci.claremont.edu/

Kirby

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