Eyepiece - more on the Vickers M55 microscope

I spent time yesterday building a chassis for the stepper mechanism. Because the microscope has been modified to accept a bracket for a video camera (one of the big, old, heavy ones - which I do not have), I was able to use the mounting for this to attach the base plate. This plate is 2.5mm aluminium salvaged from an old piece of equipment. It will need a coat of the appropriate colour paint before it is finished.

The fine focus knob

 - with the old video-camera mounting base attached

The stepper chassis attached with mounted stepper motor and drive belt.

Some drilling and fiddling, and I have a removable base plate with a stepper mounted on it. Since I'm still waiting for the electronic parts to arrive, that is as far as I can go.

Once the chassis was built, I turned my thoughts to the macro lenses. Swapping the micro optics for macro optics is a five-minute exercise. I tried the incident illumination, and found that it is useless for looking at rocks (no surprises there), so I got out the oblique illumination attachment (a mirror on a simple swivel mount).

This is the first time I have attempted to use oblique illumination using the macro lenses, and discovered that the adjustment screw was sheared off.

An hour later, I had removed the broken piece of screw and had to find a 6BA screw to replace it with. Luckily, I have a big pile of old clock-repair parts, including a selection of BA size screws.

(The pictures show the oblique illumination mirror with the new part - which needs a coat of paint)

Some work with a countersink and emery-paper on an old bronze motor bush produced a respectable head of the correct size to turn a long countersunk screw into a short screw with a smooth knob for a head.A spot of steel epoxy permanently fixed the screw in the knob (with an exposed slot head to enable release with a screwdriver, if necessary).





Now, the way the micro-focus mechanism operates is by moving the objective lens up and down - which has a coarse focus knob and a fine focus knob (which now has a stepper motor attached.

The macro mechanism, on the other hand, moves the specimen stage up and down, using a large knob and a friction brake. This is also the knob that is used to move the stage out of the way in order to swap the optics.

This knob is big and rather stiff (it operates a physically heavy piece of equipment, after all), and if I want to do image stacking using the macro system, it means another stepper to operate this knob. I also need to be able to lock the position as the stage is heavy enough that the mechanism drifts downward quite rapidly when released with the locking knob released.

The range of motion is enormous (15mm between micro examination and x5 macro) - and this means that I will need to be able to adjust and lock the stage elevation automatically. Since I am planning on using the macro optics a lot, then this is a change critical to the project.

I have managed to find a higher torque stepper in my parts bin (I may have something even heavier duty knocking around - somewhere), and so I will try that for size.