Microscopy Forum

So this weekend I was gifted a compound B&L scope from the 1920-30 era. Very cool, but it's way out of my depth, as I've only collected department store toy's before (brands like Perfect and Monolux). But hey free scope! Problem is it's missing a few parts, mainly the mirror and condenser/diaphragm. I've got a replacement fork and mirror on order that should fit nicely. I'm not sure what to do about the condenser/diaphragm though.

I found a company that sells new replacements for vintage microscopes, they offer them in "standard" 35mm or 39mm diameter. So I take out my digital calipers and measure the inside diameter of the bracket and it's just over 36mm (too big for the 35mm) when I tighten down the holding screw all the way. If I take the interior fitting out of the bracket it's just over 40mm. That would probably work if I tighten the screw down. Here's the bracket by the way:

That internal ring comes out, but I'm relatively certain it's meant to remain in place. On the top right you can see the screw that would tighten to hold the condenser in place.

What do you guys think, should I get the 35mm and try to get it to fit, or the 39mm and remove the fitting to get the larger size to fit? Or is anyone with a B&L from the same period willing to measure the the size of their condenser/diaphragm? As I said I'm kind of out of my depth working on anything this serious so any advice would be welcome.

Gekko said

It could be that in those days they fitted each instrument my hand, hence the difference in diameters?

Very likely. I have a few other B&L odds and ends including a tube and course adjustment housing that seems like it should fit in this model. It does, but without the precise feel of the one which came with it.

Gekko said

If you don't mind a jury-rigged appearance, you could use the smaller diameter condenser and pad it by cutting a section from a plastic bottle (as used for pain medication or vitamin pills) or from an aluminum soda can, depending on the thickness needed– just an idea; in other words, I would keep the fitting and adapt the smaller condenser.

I was kind of leaning that way myself. I'd hate to take an original part off just to make a replacement fit. That, and I can actually make a shim to fit a smaller part while grinding an original opening is not just more difficult but potentially dangerous.

Update!

I ordered the replacement last night before I went off to bed, and this very morning I have an email from the dealer asking me to confirm the size. Apparently they will be customizing the diameter to fit my measurements, seems they do this all the time. Not bad for only $35.00 altogether if you ask me!

Yes everything seems to be working out quite nicely. Now if only I could find a Bausch & Lomb 1.8mm 97x oil immersion lens to put in the third position on the turret. I have the appropriate 16mm 10x and the 4mm 43x but the final position had a ridiculous 44mm objective in place when I received it. Thankfully the turret was sporting three small shiny labels so I didn't have to guess at what would be correct. Not that I have any intention of using an immersion lens mind you, but having for the first time a parfocal microscope in my possession I feel an odd compulsion to screw a 1.8mm objective into that last fitting.

charlie g said

  It sure would be fun for all of us if you could 'hunt about' on that microscope..try and find the scopes serial #…and post it for us.

 It's serial # is 241697 and sports a dealer plate from Leeds Microscope Sales and Service out of Minnesota, which is funny to me as I live just a stones throw from Rochester, the home of B&L. The new condenser has arrived by now but I haven't tried it yet as testing out Euparal for the first time has been eating up much of my free time. Depending on what the cheap new condenser does I may look into getting a real (and likely costly) B&L one and really trying to complete the B&L with period parts. Do let me know if that 97x turns up I expect I'd like to purchase it. Though if I find out enough about just what's missing I may be better off (financially) picking up a more complete model to start with. There's at least a few part's I can tell are missing but I'm out of my depth. Tomorrow I should get around to posting a few pictures if you can wait.

And here's the microscope in question:

So there it is. Right of the bat one can see that the mirror and condenser are missing, as well as the 1.8mm objective and ocular. Oddly enough both stage clips are still there even if the stage is totally void of enamel. I've had scopes missing the stage clips before but never found them present on a microscope that was otherwise so incomplete. I feel as though something else is missing though, as I just can't see Bausch & Lomb including a wired circular bracket simply as a stop.

Thankfully I've got a bunch of B&L oculars laying around that my father gave me (he worked in optics for Kodak a for a few years way back) that wont look out of place. I was able to find a modern replacement mirror and condenser so I can test everything out and see if it's in good shape before I spend the time/money on period replacements. I don't really know much else about it, full-size microscopes are not something I've much experience with, but it seems a shame to let this languish incomplete in a closet somewhere.