Olympus BH2 - Stage Height Preset Lock Lever - 3 Ergonomic Options!

IMPORTANT:
This part requires printing a calibration part first and then making some simple geometry adjustments in your slicer based on visual measurements. Please follow the instructions carefully! If you print without following the directions, the chance you get a properly working part is around 1 in 36. I am currently working on some photos and info graphics but instructions are provided below for now.

Background:
The stage height preset is one of the most useful features of the BH2 when doing oil immersion microscopy. Get the object in focus with a dry lens, set the lock, rack down the coarse focus to apply oil, switch to the oil objective, and then rack back up until you hit the stop point. Especially on microscopes that haven't been serviced in a long time, this lever can become sticky and the aging bakelite can break with only moderate pressure applied. This fully 3D printed part seeks to provide a replacement for the lever without needing to fish out the brass threaded insert from a broken one.

This part: This is my take on a replacement for the lever with some tasteful changes. It includes printed M42x1 threads which easily mesh onto the receiving original Olympus part. Because the clamping face must be absolutely flat and consistent, the part had to be printed with this face up - this left the lever and peg stop as floating cantilevers. Using stock supports for these turns out ugly, so I designed my own breakaway supports that meet up with decorative pyramidal channels of my own design. This way there are no overhanging areas on show faces and the part has some visual flair. I redesigned the peg stop to be a peg "catch" with a little flexure grabber. With a little pressure applied, the catch will snap onto the peg and the lever will remain securely stowed instead of floating as in the original design. With this new feature, new ergonomic options become possible. I offer two ergonomic variants - one where the lever stows vertically and is pulled forward and pushed down to lock, and another where the lever stows 45 degrees away and locks 45 degrees forward. I think both variants are better than the original approach.

Calibration process:
The BH2 stage preset lever systems are like snowflakes - the thread orientation is unique from unit to unit - the original parts are not interchangeable between units. Because of this, we need to figure out what the correct orientation of the threads is for your exact microscope and adjust the STL accordingly. I've set everything up so this is pretty straightforward. I'm assuming you're starting from a partially torn down focus system with the old lever removed and the rotating lock ring installed in the threaded ring - it should look like Figure 81 in Carl's teardown manual. Note: This calibration routine is exactly the same for every variant of this part.

1. Choose your preferred design and import it, set global printing parameters accordingly (see below) and do a test slice to make sure there's nothing funky going on. (You will get a message about floating cantilevers - ignore this). Then turn off the printability of the part or delete it temporarily. From now on, do not change any print settings - stay in the same project.
2. Import the calibration tool and print it. Use the same settings and the same filament you plan to use for the part.
3. Install the tool on the microscope - make sure the rotating lock ring is in place, you don't need anything else on there. It should spin on easily, then snug it until it's hand tight - don't go crazy, but pretty snug.
4. Starting from the large div on the tool and going to the hole for the stop peg (located below the knob), count the divs in between. Major divs are 20 degrees, minor divs are 10. Take note of what direction you had to go from the big div to the hole - write it down like this: "Counter-clockwise 60 degrees"
5. Now load the lever part back into your slicer. Right click it and split it to parts (not objects). View it from the top looking down at the build plate.
6. Select the central part that has the thread geometry and rotate it about Z with the slicer's rotate tool exactly like you wrote down before. e.g. "Counter clockwise 60 degrees" There is a small witness mark on the top of the threaded body so you can be sure the rotation went the right way.
7. That's it - print that bad boy, follow Carl's instructions to reassemble (the spring is tricky, read carefully) and it should come out quite close to nominal.

Important printing parameters:
This part should be printed with very fine layers - I used .16. This helps the threads come out nicely and the final part will look very clean. Do not use variable layer heights or anything else similar. Use 3 wall loops - this prevents infill from bulging into the clamp face and threads. Don't use a filament that has a rough surface finish - CF is generally okay, probably not GF. I've used PETG-CF and PETG and both work well. As long as you use the same material and settings as the calibration tool, you should be good to go whatever you do. Use arachne and set the wall transitioning threshold angle to 15 degrees - this is minor, but stock 10 degree arachne tends to do weird things with the layers at the flexure and surface quality suffers. I used a .6mm nozzle for mine, concentric top layers, 3 wall loops and 30% infill - feels quite strong, takes about half an hour to print. A .4 nozzle would probably work okay too but I haven't tried it. I sliced in Orca, so use that if you want to be sure the results are similar.

Breakaway supports:
The supports are designed to leave a single layer gap between their top layer and the part - your slicer may whine about floating cantilevers - just ignore it. To save a tiny bit of filament and time, you can set the support parts to: 1 wall loop, 1 bottom layer, 0% infill.

You may need some pliers to help snap the supports off if your PETG is particularly sticky, but it shouldn't be too hard. After they break off, the top interface layer may look a little scruffy - this can be eliminated by a brief flash from a torch.

Enjoy!