BrachioGraph – the cheapest, simplest possible pen-plotter

Re:BrachioGraph – the cheapest, simplest possible pen-plotter by aidenn0 on Friday June 24, 2022 @12:49PM (#31865443)

I wonder how this compares to a two-wheel plotter; I saw one of those demoed and it made surprisingly crisp drawings for how simple it was.

If you're not familiar, take an inclined drawing table, have a wheel at each top corner with cable (or string) running to the pen, making a triangle. Using a servo to retract or release the cable will change the length of that side, moving the point of the triangle. The one I saw had a simple spring-loaded solenoid for lifting the pen.

Biggest downside is speed is limited by how fast gravity can keep a releasing cable taut.

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Re:BrachioGraph – the cheapest, simplest possible pen-plotter by jonah on Friday June 24, 2022 @03:52PM (#31868436)

I've seen this mechanism as a CNC router for cutting pieces out of a sheet of plywood. Seems like it would work better for that use since the feed speed of a router needs to be slower than a pen in general.

This is the first Open Source one I came across with a quick search: https://www.maslowcnc.com/

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Re:BrachioGraph – the cheapest, simplest possible pen-plotter by derekenos on Friday June 24, 2022 @07:41PM (#31870910)

I was inspired by my Maslow CNC to build this polar plotter: https://derekenos.com/project-weezel

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Re:BrachioGraph – the cheapest, simplest possible pen-plotter by b15h0p on Saturday June 25, 2022 @02:13AM (#31872990)

Wow, this looks so cool. Do you have a BOM or some schematics or even source code lying around? I would be interested to try something like this myself.

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Re:BrachioGraph – the cheapest, simplest possible pen-plotter by kragen on Saturday June 25, 2022 @09:53AM (#31875313)

That's awesome! What things worked surprisingly well or poorly, and what problems did you run into?

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