USB Microscope

Details

As the junk that can be used to assemble this is so varied, I can't give step-by-step instructions as to how to build your own... but I can document my own build to show you how I did it myself.

I got hold of some bits of old vintage Charles Baker microscopes from E. bay and there was enough there to reassemble the body of a microscope with no eyepiece or objectives.

My first plan was to machine a dummy objective to hold the augmented webcam... but I got the same surprise that anyone else who's wanted to hack around with cameras or microscopes... optical threads are somewhat "unusual" and the taps and dies to cut those threads are terrifyingly expensive.

Machining a cylinder of aluminium to fit the holes for the microscope's objectives and the webcam would be simple enough but cutting the thread on it's end would have cost me very nearly the price of a top-of-the-range USB microscope....... :/

So, here I'm modifying an existing objective that's (obviously) already got the screw thread on it anyway.... and these can be obtained from E. Bay at not too shocking a price if you wait around for the right one.

Components

1 × Old junked microscope body.

1 × Scrap microscope objective

1 × 2 M3 screws

1 × M3 tap

1 × DVD + CD drive

Build Instructions

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1

Screw Thread on Microscope objectives

If you've tinkered with optical devices before, you'll be familiar with the threads being weird (non) "standard" sizes and the wallet-unfriendly prices you can expect to pay for taps and dies.

Most microscope objectives use the standards of The Royal Microscopical Society (RMS) for universal compatibility.
Which, I believe is the same as the Deutsche Industrial Normen (DIN) standard. (please correct me if I'm wrong)

The old microscope bodies I found on E. bay are of mid-last-century English manufacture and I'd assume they are as RMS as you could possibly be and the objective I've used is (or was) DIN A 10X and they seem to fit together perfectly.

If you want to start your quest for parts with a trip down this rabbit-hole, here's where I started:

https://www.microscopyu.com/microscopy-basics/microscope-objective-specifications
2

Getting The Lens Out (1)

Your objective is likely to be built differently to mine and you'll have to use your own ingenuity to prepare it. I mentioned that optics seem to love their own size standards, well I needed custom tools too:

I cut a piece of 2mm toolsteel to the right width to match retaining ring inside the objective. drilled a couple of holes in it, hardened and tempered it and then ground the end to fit the slot in the retaining ring like a screwdriver would. I mounted this on an old axle "harvested" from a broken dot-matrix printer (quick tip: dot matrix have loads more useful metal parts than more up-to-date printers). This axle was round with one flattened face that I could easily join the tool steel to. I matched the holes by clamping the tool steel to the axle and punching the axle through the previously drilled holes in the toolsteel. After tapping the holes in the axle, I it could be fixed with a pair of machine screws (I think they were M3). The final thing did come out a bit wonky but it did do the job. I also squared off the other end so that if it needed a bit of effort getting the retaining right moving, I could use a tap wrench as a handle (it didn't really need this in the end)
3

The cap on the lens assembly

There's a small cap screwed on in front of the lens assembly. That can easily be unscrewed with a thumb and a bit of friction:

We'll need to save this for later modification.