31–40 of 51 posts
Wait a second, how'd they upload a video to Vimeo? I thought Vimeo shut down. Edit: Well I guess I just made that up somehow. I swore I read something about people moving their content because Vimeo's over.
I've wanted a pen plotter for so long, but mainly to draw sharp geometrical figures. I don't think this would scratch the itch but I'm hopeful something will appear for <$100
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Were they noisy, or did they quantize motion, or were they too weak, or what?
Hysteresis kills this project
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Why, what are the super fiddly parts? It's very generally true that, when you have money and a functioning economy, buying a product to do some well-understood task requires less effort than building something to do it yourself. Similarly, it's easier to look up the answer to a well-known math problem than to solve it yourself. The advantage of DIYing existing things is usually just that you build competency you can…
Love that analogy at the end, very well said
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Why, what are the super fiddly parts? It's very generally true that, when you have money and a functioning economy, buying a product to do some well-understood task requires less effort than building something to do it yourself. Similarly, it's easier to look up the answer to a well-known math problem than to solve it yourself. The advantage of DIYing existing things is usually just that you build competency you can…
I haven't tried this, but I would expect that maintaining precise and steady down-force is especially tough. The axidraw does a lot to make that work well. Sloppy x/y motion (as you'd also expect here) can just be treated as a "lofi" aesthetic, but sloppy z can mean having whole sections fail to draw or your pen digging into the surface and producing unrecoverable tears and drags of the paper.
I've wanted a pen plotter for so long, but mainly to draw sharp geometrical figures. I don't think this would scratch the itch but I'm hopeful something will appear for <$100
I would recommend a Cricut machine. Far less maintenance and everyone in the family can use.
Get any old Roland clone. You can often score an old USCutter on Craigslist for similar prices, the hardware is way more durable, and it's all simple parts you can replace without vendor lock-in. They speak HPGL and there's a million softwares to drive 'em, including Inkcut which sorta sucks but it's free.
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Hysteresis kills this project
The problem was that their potentiometers had too much hysteresis? That seems like something you could compensate to a significant degree in software?
With the lever-arms on these things, you're going to get into all sorts of details with things like the pitch-circle variation of the plastic gears, which may have been nearly-ideal when they were produced but will become uneven with wear.
I would go the other way and grab any broken 3d printer, rip off the hot-end and stick a pen in its place. It's slower by default but a thousand times more precise, and you can tune up the speed now that you're no longer whipping around a heavy extruder or waiting for plastic to flow.
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I haven't tried this, but I would expect that maintaining precise and steady down-force is especially tough. The axidraw does a lot to make that work well. Sloppy x/y motion (as you'd also expect here) can just be treated as a "lofi" aesthetic, but sloppy z can mean having whole sections fail to draw or your pen digging into the surface and producing unrecoverable tears and drags of the paper.
Wouldn’t any spring work for application of downforce? Not that I’m immediately clear on how to attach that to the brachiograph, but for purchasable machinery it seems it should be relatively easy to solve.
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The problem was that their potentiometers had too much hysteresis? That seems like something you could compensate to a significant degree in software?
It's not really predictable; you'd need a camera watching it to continuously train and compensate and improve. Which would be neat, honestly. With the lever-arms on these things, you're going to get into all sorts of details with things like the pitch-circle variation of the plastic gears, which may have been nearly-ideal when they were produced but will become uneven with wear. I would go the other way and grab any…
(I'm theorizing, because I think theorizing is valuable, but I want to be careful to distinguish theoretical predictions from reports from experience.)
The broken 3-D printer idea is brilliant. Unfortunately, right now there's only one broken 3-D printer for sale near me on MercadoLibre, and it's an SLA printer, so it only has one degree of freedom of positioning. However, it won't be a thousand times more precise; typically RepRap FDM printers like the Prusa or Creality have positioning errors on the order of 0.1 mm, and a thousand times less precise than that would be an error of 100 mm. The BrachioGraph drawings seem to have an error of about 2 mm, only about 20 times worse than a bog-standard RepRap, and actually, 20 is less than 1000.