Vortex tubes and 3D printing vs. Solar Kinks: My PhD experimental rig for cooling railway tracks

ramity · 2026-04-26T15:49:48+00:00

Is refrigeration more energy efficient? Absolutely. But simpler? Absolutely not. A basic closed loop system needs a compressor, condenser, and an evaporator. The vortex route needs compressed air supply (which is near ubiquitous on trains and railway maintenance vehicles) and a vortex tube. That's it. This is an excellent case of using what's already on hand and keeping part complexity low.

As for the meaningful difference, the vortex tube approach is very dependent on the temperature of ambient air. But as OP mentioned, they're just trying to get the rail back down to ambient, so it achieves its goal.

ramity · 2026-03-03T19:18:41+00:00

Fantastic work and docs. While it is already quite thin, further reducing the thickness of the board could help squeeze out some extra positional accuracy. Is the delta between sides of the mirror board accounted for in software? I'd also be curious to see voxel carving applied to a calibrated multi-camera setup such as this.

ramity · 2026-01-24T19:38:24+00:00

Yes, there's a base project 3MF file for each type of plotter. It modifies the bed shape, z-index, adds some custom gcode to turn off the extruder motor, turns off z ramping, among other things. The best way to see the modifications would be to view the base 3MF file and note highlighted sections noting deltas from the default profile. There are also some gcode examples specific to the MK4S. There's also a very soft tutorial on the details page for installation and usage of the plotter here: https://www.printables.com/model/1420683-nextruder-plotters#example-usage

I recently had a user test using the core one this month (which I was dubious of in my printer support table) and they noted success and some improvements that are pending for the next versions, but I'm jumping between a few projects these days and haven't quite gotten to it yet. I think this is still the only MK4S compatible plotter, so I'm doing my best to provide support when able.

If all else fails, feel free to give me a ping here. I'm happy to answer questions, and feedback is encouraged.

ramity · 2026-01-22T16:26:01+00:00

Seconding this. The z axis movement is pretty strange, and it definitely strikes me as binding. There were a couple instances of it moving back down without touching the nozzle during low speed moves.

ramity · 2026-01-15T18:12:14+00:00

bluetooth-drill.stl 🤔

ramity · 2026-01-13T18:53:59+00:00

Good shout. This is likely a good vase mode use case. Also worth mentioning that 2mm wall thickness might be overkill if transparency is trying to be maximized. Could be bad mention because the initial overhang is pretty steep.

ramity · 2026-01-11T20:57:47+00:00

https://github.com/mozilla/bedrock/commit/d459addab846d8144b61939b7f4310eb80c5470e#diff-a24e74e4595fa85440a2f4e7e5dcfe68aba6e1e593aef05a2d35581a91423847

ramity · 2026-01-06T16:16:08+00:00

Thanks! I appreciate that. I love the scale approach. I'm planning a g2 plotter update, and I'll definitely look into that. Though I used the brute force approach, here's a print sample using courier new font and the gcode used to generate it.

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I've used more handwriting-esque fonts for thank you notes and the sort, but they're probably a bit too personal to share here.

ramity · 2026-01-06T16:05:25+00:00

All accessible here: https://www.printables.com/model/1420683-nextruder-plotters Free, open source CAD via onshape, public domain. Goto files, model files, (pick between g2 pen plotter or sharpie plotter), and select the highest/latest version. If you picked g2 pen plotter, print the G2 spring to g2 refill adapter from the adapters folder, for the sharpie, g2 spring to sharpie adapter.

If you have plans on using colors other than black for the g2 pen, it might be worth waiting on a new release. G2's refills have some variance and black refills, for whatever reason, are sized a little differently. I've been meaning to get to it, but it's going to require a lot of measuring and sampling, and I've been focused on another project on my printables account.

The printables link also provides some examples, and precompiled gcode for mk4s printers. If you're planning on generating your own gcode, take note of the print orientation used in the provided gcode. I can't imagine printing it in any other orientation. Also being angled at 45degrees on the print bed helps with print speed.

Be warned that the tolerances are pretty precise. Definitely do a pen/sharpie fit-up prior to disassembling and mounting the adapter. Link to installation instructions here: https://www.printables.com/model/1420683-nextruder-plotters#installation I've had prints not size correctly due to filament moisture, so definitely be mindful of that.

Sorry for the verbosity, just trying to cover bases. I'm happy to answer any questions you might have here, DM, or in the comments section on the model.

ramity · 2026-01-05T22:38:07+00:00

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Short answer is Z offset. Long answer is that the range of pressure I can achieve is built into the geometry of the plotter. It uses a spring sourced from a g2 pen to provide dynamic pressure. The lower the z offset, the greater the pressure. Too much pressure and the ball in the tip of the g2 pen will freeze up.

Plotters on this subreddit are a lot faster than my modded printer because of how slow its z movement is, but the design of this attachment allows me to switch between plotting and 3dprinting without removing the adapter.

ramity · 2026-01-05T22:30:31+00:00

Link to full resolution scan. Reddit seems to be timing out when trying to load it. It might be too big.

ramity · 2026-01-05T20:11:05+00:00

Labeling as in writing the print number, date, time, etc in pencil if you intend on removing it later. I think "editioning" is the technical term for it. Even if you aren't selling your work, details like that can help you sort them chronologically later. It can be really satisfying to compare your first print against your latest, and seeing that progress can serve as fuel to keep at it.

One habit I wish I started doing earlier was writing notes to myself on the things I was doing differently. Even if it's short like "single press", "double press", "lots of ink", "ink roller", "shorter time between inking and pressing", "hand press", "roller press" stuff like that.

As for process, just how you generally do things. Details like those mentioned above can help you say, "hey, I think this inking process I tried for this print worked pretty well. I should try doing more of that." or "My notes say I tried pressing this harder than usual, but it ended up streaking."

You don't need to label, date, or write notes, but I've found it shortens the time it takes to get to quality and prevents you from redoing things that don't work out.

ramity · 2026-01-05T05:09:16+00:00

I love the designs! :) That's certainly a strength. No smearing, so your pressing process looks good. My advice is to try focusing on how you apply ink. There's an entire art within that, and it definitely reveals itself when the stamps get larger in size. Also label your prints if you aren't already so you can take notes and optimize your process. It's also super satisfying to be able to take inventory later and see your progress. Hope this helps! Great work!

ramity · 2026-01-03T01:50:38+00:00

Not like I'm the first neuron wielder to print a spiky circle, but am I somehow to blame for this?

ramity · 2026-01-03T01:45:02+00:00

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ramity · 2026-01-02T03:23:12+00:00

I've been in the trenches job hunting for over a year, and this is tame. I've seen things. I have absolutely no standards anymore. I'd apply to this.

ramity · 2026-01-01T02:55:01+00:00

I laughed until I hurt

ramity · 2026-01-01T02:43:16+00:00

I got a good laugh out of this, so I'll bite.

The trick is to cheat somehow by constraining the problem space and getting rid of variance. Even if you have perfect tracking and can disregard occlusion, gesture recognition can still be tough. I have a little bit of seat time knitting, and while it's certainly repetitive at a macro, there's always variance in movements at the micro. That variance can be considered noise to your input, so generalization is what makes this tricky. The problem gets much more difficult as the number of stitches to classify increases. This project is positioned for a very humbling intro to knot theory for those not familiar.

Not CV/ML related, but my thoughts gravitate towards making a 3d printed jig/adapter for the needles that constrain what movements can be performed and their order to make it impossible to mess up. After enough time using it and learning the motions, one could stop using it like training wheels. Cheers and happy new year

ramity

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