Wanted: critical feedback to help me improve this stage clip design. When I’m happy with the design, I intend to publish it under a permissive license to Thingiverse, and if the OpenFlexure team is happy with it, incorporate into this project.
I wanted an easier way to hold slides on my stage, and I was inspired by the designs shared in this earlier thread. I was also inspired by some of the fancier claw-type spring clips I’ve seen on really nice microscopes, like this:
Here’s my design:
My design criteria roughly were:
- Require no additional hardware, use existing stage mount captive nuts
- Easy printing: No supports, infill doesn’t matter
- Reliably locate a slide +/- 1mm in x/y/z for easy swapping of slides
- Hold the slide to prevent shifting mid-observation
- Use a compliant mechanism in the spirit of flexures
- Don’t lose z-height by raising the slide above the existing stage plane
- Resilient to reasonable use
I have a few ideas for some final improvements. The clip’s slide-facing surface and the 90-degree slide corner holder both have slight angles on them, intended to add a slight down vector component to the spring force applied. This should help keep the slide in contact with the stage plane, but it’s not perfect. I plan to add a notch near the 90 degree supported corner to keep the slide from slipping in the -Z direction. You can see this in my photo taken from the stage plane, where the right side of the slide is just slipping downwards.
Here’s the .stl in case anyone wants to print one:
slide_holder_spring_v3.stl (168.6 KB)
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An improved slide holder would be very welcome. I like both of the designs.
Without printing one I have a couple of comments. The inside 90 degree corner that holds the slide will be very slightly rounded on printing. Slide corners are often completely square. A rebate circle in the corner might be helpful, in the same way as you would on a machined inside corner. The generic slide holder in your first image has a square rebate on one side of the corner. Secondly the z-height criterion is very restrictive and has halted many of my plans. Relaxing that to 0.4mm (two layers) would allow you to put a base layer under the slide that would stop the issue with one corner being pushed below z=0. The other way to get a base part would be to print it separately and screw it on from below. I have only just realised that that could be the small self-tappers so does not need all the space for an M3 nut.
If there is a really good design for a slide holder stage that needs a base 5 or 10mm thick, I think it is possible to have the optics module that bit higher. It would mean a different set of optics modules for that use, but it might be considered worth it for ease of use with slides. The optics modules would be functionally the same, with mounting points moved.
Just to be clear, that more rectangular slide holder from before is @Noli 's contribution.
Here’s my current version:
I made some allowances on my “Don’t lose z-height” requirement and raised the stage 1mm with some slide supports. This makes the slide much more secure when held by the clip. I also added that rebate circle in the corner area like you suggested.
The system isn’t that rigid, but neither is the microscope itself. I poked and nudged the slide and holder clip a few times and watched the focus go out of whack on my camera feed, but it seemed to return to the same position when I stopped applying force. It’s hard to tell what’s the microscope flexing and what’s my addition.
I’m happy with this, and plan on at least using it myself. I welcome anyone else using it, too:
slide holder body_v4.stl (44.9 KB)
Print settings: I used PLA, 0.4mm nozzle, 0.2mm layer height (doesn’t really matter). No supports, flattest side down, some nonzero infill.
Important: Make sure your slicer doesn’t put the seam along the flexure. Direct your slicer to put the seam somewhere unimportant like the clearance arc between the screw holes.
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