Coarse Focus Doesn't Turn

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boggsmtn
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Location: Georgia, USA

Coarse Focus Doesn't Turn

#1 Post by boggsmtn » Wed May 12, 2021 6:27 pm

I just bought this Bausch and Lomb microscope. It's from the '60's. Everything looks in really good shape except the coarse focus knob won't turn so the stage doesn't move up and down. I found the manual for the Dynazoom and it shows a stage set screw, but this one doesn't have one that I can find. Am I missing the screw and the stage is locked? Or it the knob likely frozen? Thank you for any help. Image

lorez2
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Joined: Wed Apr 21, 2021 2:06 am

Re: Coarse Focus Doesn't Turn

#2 Post by lorez2 » Wed May 12, 2021 10:11 pm

I suspect the lubricants are all dry. I have not worked on one of these for a very long time. Maybe I should dig one out.

lorez
Nikon 80i

boggsmtn
Posts: 9
Joined: Wed May 12, 2021 6:14 pm
Location: Georgia, USA

Re: Coarse Focus Doesn't Turn

#3 Post by boggsmtn » Wed May 12, 2021 10:20 pm

Would putting some solvent or lubricant between the knob and the arm be worth a try?

lorez2
Posts: 113
Joined: Wed Apr 21, 2021 2:06 am

Re: Coarse Focus Doesn't Turn

#4 Post by lorez2 » Thu May 13, 2021 12:50 am

All of the dried grease is internal and adding a solvent as you suggest is not going to help. Disassembly is the answer. I don't have any diagrams or directions. It's a very robust microscope... no plastic... HAHAHAA

lorez
Nikon 80i

apochronaut
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Re: Coarse Focus Doesn't Turn

#5 Post by apochronaut » Thu May 13, 2021 1:15 am

I don't know the "lab II" as well as others but there is a considerable shaft to bushing surface area on many microscopes, where lubricant can dry and lock things up. Moreso than in the actual mechanism. Getting some light penetrating type oil onto the shaft where it can work it's way into the interspace between the shaft and bushing might do wonders. Worst case scenario is, it won't do enough and a complete teardown, cleaning and relube will be in order. That is generally indicated anyway but trying to free the shaft up might get the scope up and running. On the AO 10 for instance that is usually the area of primary stiffness.

BramHuntingNematodes
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Location: Georgia, USA

Re: Coarse Focus Doesn't Turn

#6 Post by BramHuntingNematodes » Thu May 13, 2021 2:05 am

That is the other scope I use about every day. The grease in the interpupillary adjustment mechanism in the head was locked with dried grease. A bit of light oil and working it back and forth loosened it just fine. I have an exploded diagram if that would be useful. The set screw is to keep the condenser from smashing into the stage and is a spring loaded affair on the condenser focus block. Moving the condenser down would free the stage if that were the thing blocking it. It is a sturdy scope indeed, and the adjustment mechanism is elegantly designed so you likely could figure out how to disassemble and reassemble it if need be.
Last edited by BramHuntingNematodes on Thu May 13, 2021 2:21 am, edited 1 time in total.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

lorez2
Posts: 113
Joined: Wed Apr 21, 2021 2:06 am

Re: Coarse Focus Doesn't Turn

#7 Post by lorez2 » Thu May 13, 2021 2:18 am

The design of the B&L DynaZoom and Dynoptic microscope focusing system is completely different from the AO10 and probably the lab II also although I don't recognize the name lab II unless it is the Nikon LaboPhot II. If it is the Nikon the B&L is also different from that model as well. You could probably replace the set screw for the focus stop. Just guessing, but the size may be 4-40 or 6-32. When I'm at the shop tomorrow I will check.

On an editorial note, I think the Dynoptic and Series 10 were the last hurrah of American made microscopes. This is not to say that later AO and B&L models were bad, but there was a distinct difference.

lorez
Nikon 80i

boggsmtn
Posts: 9
Joined: Wed May 12, 2021 6:14 pm
Location: Georgia, USA

Re: Coarse Focus Doesn't Turn

#8 Post by boggsmtn » Thu May 13, 2021 8:55 am

Thank you for all the help. I'd appreciate an exploded view if it's possible.
I know nothing about microscopes, so excuse some dumb questions. I basically just use one for fecal egg counts on my flock of sheep. I was looking to upgrade my old one and found this one and went "WOW". Someone mentioned I could remove the set screw. What set screw? The only one I see with a quick look is on top of the slide and it's not easily accessible. There is one in the Dynazoom /Dynoptic manual on the arm, but this one doesn't have that one. Can anyone identify the model? I'm fascinated with this microscope and can't wait to have it functional. It's inscribed with the original owner's name and date of graduation from John Hopkins, which I thought was interesting.

BramHuntingNematodes
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Location: Georgia, USA

Re: Coarse Focus Doesn't Turn

#9 Post by BramHuntingNematodes » Thu May 13, 2021 4:59 pm

Image

Image
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

boggsmtn
Posts: 9
Joined: Wed May 12, 2021 6:14 pm
Location: Georgia, USA

Re: Coarse Focus Doesn't Turn

#10 Post by boggsmtn » Thu May 13, 2021 5:24 pm

You guys are great!! We removed the base and cleaned the gears with WD 40 and it's freed up now.
Now what do I use for a lubricant?

troy
Posts: 4
Joined: Thu May 13, 2021 5:22 pm

Re: Coarse Focus Doesn't Turn

#11 Post by troy » Thu May 13, 2021 5:28 pm

Maybe the adjusting mechanism in the head is locked due to prolong unused. Just apply a little bit lubricant or oil and try to free it up by back and forth motion. It might help you.

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