CAD Designs for Microscopy

Figured I’d post this here to get a general discussion going on this subject. Of likely interest also are the thread files for SM1 and C Mount, which can be used to make 3-D printable adapters for microscopes. http://www.austinblanco.com/blog/8020-extrusion-optic-sliders/

At some point it might be useful to build a community repo of such designs. Especially things like custom sample holders or similar commonly used items. Or objective threads…

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Nice post, thanks! I also have some CAD designs on Thingiverse, for example DIY motorized 3D flipping mirror mount. I think Thingiverse is better for CAD files than github, since it has built-in 3D vizualization. One can immediately see how the model looks. One can also comment, remake, and build collections of things there.

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Github 3D renders my STL files (example: slider for polarisation filter)…

Screenshot_20190826-080212

What file format is best for sharing?
STL can’t be edited in a practical way, or?

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Oh, I take my statement about github back! Yes, STL is essentially a mesh, there is no way to easily change the parameters of a part. Many designs are made in parametric openSCAD, but modeling in it a bit tedious and non-intuitive (essentially scripting). I guess it’s best to share whatever source files one uses (e.g. SCAD, IPT or SLDPRT) and also STEP and STL files for cross-software compatibility.

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I have some CAD designs here:
3D-printing

Also, NIH hosts a large collection of different 3D printable designs including many for microscopy.
NIH-3Dprint

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Speaking of threads. Fusion-360 has an option to model threads - meaning they show up in the final STL file! I used to use a lot of hexagonal nut catches in my designs. Now I just model the thread and print. A regular screw is usually sufficient to ‘tap’ a printed thread.

Also, Thorlabs has a list of objective thread specs you can use. However, I would recommend a objective adapter permanently screwed or glued into your printed plastic mount. Printed plastic doesn’t do well with fine threads after a few uses.

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Piling on here - THOR doesn’t list some of the more common specs we use, but Fusion360 can accept custom threads and I’ve managed to cook up a few useful sets. I have a post on how to do all this here - http://www.austinblanco.com/blog/thor-sm1-threads-in-fusion360/
The Nikon thread was tricy - there isn’t a great spec on that, but the thread file is in the same github location as the thor stuff as well as a bunch of other “optics related” threads (Like 42mm ones for camera lenses) .

  • Also note that an annoying feature on F360 is that when it updates it oftentimes loses the old custom thread stuff, causing you to copy/paste the thread files to the new version subfolder, just something to be aware of!
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Grab-bag of parts I have designed are here:

with some specific projects with more parts, like a laser launch:

or 3D printed magnetic coverslip + sample holders:

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I second that, 3D printing of threads never worked well for me. Tolerances of most 3D printers are too loose for an optomechanical thread like SM1, and also the plastic is too soft. Metal only, imho. In worst case, machined and threaded engineering-strength plastic.

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I’ve had some luck with really big printed plastic threads for short depths. I made some 25mm optics holders and retaining rings that worked fairly well, but the thread pitch had to be in the 1mm range, with thread depths scaled to match.

Printed standard screw threads (#4, #8, M3, M4, even M5) are more forgiving because screws are much deeper than an objective mount, C-mount, or retaining ring. Longer cylinders like screws tend to find an average center once you “tap” them into a printed female thread for reasonable multiple of the pitch. Plus most screws go in and out just a handful of times.

But yeah, don’t screw a $10k objective lens into a printed plastic thread mount. Splurge on a little metal.

Not sure if I’m getting lucky or it’s random chance, but I’ve printed Nikon objective threads, SM1 threads and C mount threads with great success. I use a Prusa MK3 i3 w/ prusament PLA or PETG and default settings @ 0.15mm layer height.

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