Cartesio – Low-cost Cartesian plotter robot | Hacker News Reader

Cartesio – Low-cost Cartesian plotter robot

robottini.altervista.org

93 pointssatchet16 comments

I don't understand the decision not to use CoreXY. I have a very very similar plotter that also cost me next to nothing using essentially the same BoM as this. It's directly descended from this one [0]. It can absolutely fly, I've spent some time tweaking it but I can reliably and accurately drive it at something like 20cm/s. That's largely a factor of the low inertia of the CoreXY design, which keeps both the main steppers stationary during operation.

Anyway, plotters are dope and to anyone thinking of building one of these, I highly recommend a CoreXY based design.

[0] https://www.thingiverse.com/thing:1514145

Not sure if this is a dumb question, but what is CoreXY?

https://corexy.com

CoreXY is interesting, and seems especially well suited to plotters, where you don't need to worry generally about the speed of the tool. I've seen CoreXY machines doing circles at two or three linear meters per second (!) with print heads on them, I can only imagine how fast a light pen plotting head could go. Is there a reason why people aren't using thin cables or wires instead of belts at this point? If you used wires you could have a simpler crossover, I think (wouldn't need the extra pulleys); this could also reduce belt inertia, if that's of any importance.

Plotters are addictive and lovely - look for #plottertwitter on twitter.

I've always loved this spray painting printer (poor quality video, unfortunately):

< https://youtu.be/V4aXw0Zotzw >

The people that made AxiDraw also helped put together a kid's kickstarter plotter "Sylvia's Watercolor Bot" which is fun. They also have a plotter that draws on eggs...

I don't have an AxiDraw, but I'd be willing to bet the differentiator from homebuilt is the rigidity of the platform and being able to get very consistent results. (Personally, I'm a fan of 80s pen plotters from HP and Rolond.)

FYI, if you already have a 3D printer, you can totally use it as a 2D plotter (if that's not obvious).

And you can totally use a fountain pen if you feel like it.

In action: https://www.instagram.com/p/BlQHk43gwra/

Final result: https://www.instagram.com/p/BlJHawZgFi1/

Same, with a ballpoint: https://www.instagram.com/p/BlJ8dgmAaTA/

How do I do this? Installing the pen and adding some initial gcode to raise the Z axis above the bed so the nozzle doesn't touch isn't a problem, but what generates the drawing gcode?

I wrote code that generated this particular G-code for the Dragon curve.

In general, there's software to convert PostScript or DXF to G-code (used with e. g. engraving machines).

The G code to move in XY is simple enough (G0 x y) that you could write a converter yourself.

G code is simple, I'm just not sure how simple reading the curves would be. I worked around this by exporting as a png and having Cura slice that, then writing a script to extract a single layer. It works beautifully, now I want to see if I can make PCBs with it, it would be a revolution.

Is there a practical use for this? I’m thinking if my 3d printer does I could repurpose it for this.

I've spent the last several years working with this scale of robot at my start-up. The practical use is mobile phone, tablet, and general touchscreen testing. In some products, such as automotive head unit displays or any medical device with a touchscreen, there are legal and company policy rules requiring that functional testing of a device must match human actions as closely as possible. Which means you can't only test the device through USB or some other back-end developer interface. In other cases, performance/latency testing teams want to test a touchscreen device as a black box, meaning with no extra instrumentation running on the device-under-test, to get good real world performance data. In all these cases that means a capacitive tablet stylus, instead of a pen, is attached to the end of a robot like Cartesio.

Huh, that's really interesting to learn. I'll file it in my big file of "Never thought about it, but makes sense"

(sorry, nothing otherwise constructive in this comment)

I just spent a day upgrading my printer and playing with Gcode, but it wasn't until your comment that I realized just how easily I can write a program that outputs gcode itself and add a pen so I can have the printer draw on paper. I'm going to have to test this right now.

This looks like the logical next step after building a brachiograph!

https://brachiograph.readthedocs.io/en/latest/

https://news.ycombinator.com/item?id=21281525

I wonder if we might see a resurgence of these plotters ala 3d printers.

A tronxy x1 is $85 right now for a full small form factor 3d printer.

a review of the tronxy x1 https://www.techradar.com/reviews/tronxy-x1/2 check aliexpress or similar for the $89

self upgrade to make it better: https://www.reddit.com/r/3Dprinting/comments/81xkut/tronxy_x...

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