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BrachioGraph – a cheap, simple pen plotter
- cbertschy 7y agoI saw it in action, draws beautiful and unique pictures :-)
- frankwiles 7y agoDaniele had it do my portrait at DjangoCon last month and it turned out pretty well despite the fact I'm so hairy! https://twitter.com/fwiles/status/1177018222987448321 https://twitter.com/fwiles/status/1177018222987448321
- Accujack 7y agoJudging from the pic, I'd say "Hairy" is something this plotter does well. It's a neat toy and a cool hack, but it's not useful for a lot except artistic sketches.
- DanieleProcida 7y ago"not useful for a lot except artistic sketches" - what could be more useful than that?!
- test1235 7y agodid you have a belt across your face?
- frankwiles 7y agohahaha no
- Cheyana 7y agoIt looks like the robot adds 10 pounds.
- klyrs 7y agoIt looks like there's an artifact in a certain range of arm extension; the "belt" effect appears in [1] too. I just went from "this is cool but what would I do with it" to "I wanna make one and try to debug it." https://brachiograph.readthedocs.io/en/latest/_images/brachiograph.jpg https://brachiograph.readthedocs.io/en/latest/_images/brachi...
- DanieleProcida 7y agoOn GitHub: https://github.com/evildmp/BrachioGraph https://github.com/evildmp/BrachioGraph
- akamor 7y agoIs there a video somewhere of this in action?
- cbertschy 7y agohttps://youtu.be/Rn4X2ZgZvsk https://youtu.be/Rn4X2ZgZvsk and https://youtu.be/u4Jh1daCl60 https://youtu.be/u4Jh1daCl60
- FinalAngel 7y agoHad the chance to see it live once in Amsterdam thumbsup
- diafygi 7y agoIt's my understanding that higher quality plotters/3d printers/mills' accuracy and precision come from higher quality motors (e.g. stepper motors instead of servos). Will it be possible to someday just put cameras on the plotter which watch the current print and self-correct as needed? That's basically what our eyes do when we write/sculpt/carve. Will cheap motors + cameras + software eventually meet or exceed the quality of expensive high precision motors/controllers?
- tpmx 7y agohttps://en.wikipedia.org/wiki/Visual_servoing https://en.wikipedia.org/wiki/Visual_servoing seems related.
- deleted 7y ago[deleted]
- yakz 7y agoRigidity is a major factor--if you inspect one you'll notice that high speed and high repeatability machines (e.g. a 6-axis +/- 0.020mm repeatability manipulator) are made from rigid (often high-mass) components with robust joints.
- diafygi 7y agoI see. I wonder if my hypothesis is still valid, even given lower quality rigidity. Human arms aren't made of big heavy metal rods, yet we can still draw beautifully. Couldn't cameras and software compensate for cheap unstable draw arms?
- roland35 7y agoI can see this helping with low-force motion such as a pen-plotter but I think with things like 3-d cutting there just isn't a replacement for rigidity and high-power motors that can maintain a consistent cutting feed rate for a quality finish.
- hortense 7y agoYou can improve the precision by using visual feedback, but there are movements that are impossible to do if you don't have precise enough motors.
- deleted 7y ago[deleted]
- Ididntdothis 7y agoI love pen plotters. When I worked with CAD we still had them. It was so much fun seeing it slowly working on a technical drawing. Laser printers are obviously much better and faster but much less fun to watch.
- dougmany 7y agoOh yeah. When it would change colors it would run over to the pen holder and pick up a new color. That was fun to watch.
- ficklepickle 7y agoThat reminds me of the create-a-card machine that was in Hallmark stores in the 90's! I had forgotten about that. I remember watching in awe as it drew a Simpsons-themed card.
- C1sc0cat 7y agoBack in the day we used to use HP's biggest and badest Super A0 plotter for small print runs used to park it the computer room (to keep the temperature controlled) and let it run all nig
- HeWhoLurksLate 7y agoThis is awesome! To the people that made this happen: Thank you so much! I've been wanting something to demonstrate how the gap between hardware and software is fairly easy to bridge at this point- thank you for sharing something that demonstrates this well!
- cpach 7y agoIf you’re in to this kind of stuff, you might want to check out the hashtag #plotterwitter. Some really good stuff there. https://twitter.com/hashtag/plottertwitter https://twitter.com/hashtag/plottertwitter
- RickS 7y agoNice! I've been enjoying the work from skullcat recently: https://twitter.com/mrmrs_/status/1159339640459059200 https://twitter.com/mrmrs_/status/1159339640459059200
- timthorn 7y agoAnd if you want a COTS replica with a bit more polish: https://www.line-us.com/ https://www.line-us.com/
- itronitron 7y agoThe line-us looks really good, the software also looks well put together.
- person_of_color 7y agoIs it hackable?
- itronitron 7y agoIt looks like people can code Scratch to control it... https://www.line-us.com/scratch.html https://www.line-us.com/scratch.html ... and there is also a programming tab that links to a github page with lots of example code in other languages.
- makotoNagano 7y agoNice stuff. Raspberry Pis are generally pretty terrible at running servo's though. Adding an intermediate Arduino would work wonders (I appreciate the complexity would jump significantly though)
- DanieleProcida 7y agoTurns, out, it's actually very reliable in practice. I'm trying to work out at the moment just how far I can go with more powerful servos: https://raspberrypi.stackexchange.com/a/104662/42583 https://raspberrypi.stackexchange.com/a/104662/42583. There are limits, but they seem to be greater than I expected, especially when the only power to the Raspberry Pi is provided by a MacBook.
- dekhn 7y agowe live in a world where a macbook can power a raspberry pi which powers servos.
- hrnnnnnn 7y agoThis looks like great fun, but I'd prefer to make something where the output is a little more precise. Does anyone know of a DIY plotter that's a step up quality wise from this one? Or maybe a site or community that lists similar projects?
- cpach 7y agoCan’t vouch for the quality but just searching for [diy plotter] yields plenty of results that look interesting.
- DanieleProcida 7y agoMore expensive servo motors will produce better results, but past a certain point, they would require more power than the Pi alone can supply. The mechanical construction also introduces imprecision.
- sleepybrett 7y agoI love my evilmadscientist axidraw but honestly they are a bit pricey. There are several chinese knockoff kits to be found on alliexpress/banggood/etc that work very well. There are also a few interesting 3d printed projects to be found on thingiverse and in the greater maker community. I've built a midtbot, fun little project if bart has boards available (https://www.thingiverse.com/thing:2587684 https://www.thingiverse.com/thing:2587684) and I've got the full BOM and have printed most of the parts for a modest sized d.i.d. plotter (https://www.thingiverse.com/thing:3789969 https://www.thingiverse.com/thing:3789969). Also don't discount polar style hanging plotters they can be tricky accuracy wise due to sway, which i've seen countered both by decreasing plotting speed and by working the potential sway into your design. Just a quick search turned up this https://www.hackster.io/fredrikstridsman/stringent-the-15-wall-plotter-d965ca https://www.hackster.io/fredrikstridsman/stringent-the-15-wa.... You can start small like that and then improve components along the way. Swapping the string for beaded cord or timing belt etc. They are patricularly interesting drawbots because if you want to plot a larger area you can just spread out the motors and add more string.
- panpanna 7y ago
- Autowired 7y agoThis is amazing and I want to add something like this to my side project list right now. But maybe it is a bit too extreme, i.e. using a ruler and glue won't save you that much money compared to using some better materials. But I guess that was the intention of the author, extreme frugality.
- ISL 7y agoWhere can we buy a Pi and three servos for $14? That sounds darn fun.
- sovnade 7y agoIt's a Pi Zero at least.
- xVedun 7y agoPi Zero ($5): https://www.adafruit.com/product/2885 https://www.adafruit.com/product/2885 4 Servos ($9): https://www.amazon.com/dp/B07Q6JGWNV/ref=cm_sw_em_r_mt_dp_U_nbiQDbCF84TB2 https://www.amazon.com/dp/B07Q6JGWNV/ref=cm_sw_em_r_mt_dp_U_... Shipping might go over $14 though.
- Tepix 7y agoA Raspberry Pi Zero is $5. SG90 servos are $1 on AliExpress. A separate power supply is recommended for the Raspberry Pi so that's what you can buy with the rest of the budget.
- DanieleProcida 7y agoBe careful, a lot of SG90 servos are fakes. Below a certain price, they all appear to be counterfeit. As far as I can tell, the real ones have four screws in the base, and "TowerPro" printed into the plastic on the top. The fakes have two screws, no brand name moulded into the plastic, and inevitably stop working quite swiftly. https://brachiograph.readthedocs.io/en/latest/explanation/hardware.html#the-servo-motors https://brachiograph.readthedocs.io/en/latest/explanation/ha...
- iamgopal 7y agoWhat is the best way to increase accuracy of such servo motor ?
- bronz 7y agoharmonic gearbox
- Tepix 7y agoBuy higher quality servos, use a sturdier material for the arms instead of cardboard. Personally I like the fact that it's somewhat sloppy. The pictures have a distinct style.
- pp19dd 7y agoBetter motor control. Timing: assuming rigidity of linear position is crappy, allow more time for it to bounce back. Speed: ramp-up speed in one direction may be different from the opposite direction. Position: accuracy of RC servos is almost not worth measuring, so many companies haven't. But you can hack it (via contact switch and something that juts out) to add a simple shaft rotation encoding and correct when needed. Software correction: draw a grid of straight lines and adjust drift in software until it looks like a grid.
- DanieleProcida 7y agoAlso it's hard to defeat hysteresis in the system, both in the servo motors (they have significant dead bands) and the mechanical arrangement of the arm/pen.
- MisterTea 7y agoYou could get a lot more precise with stepper motors paired with a micro stepping drive. Since a stepper does not necessarily need feedback the software doesn't have to close a loop but spit out position and velocity commands. Integrated stepper chips exist on breakout boards which keeps the design simple as it will handle the complex microstepping current control. The entire design would not increase much in complexity at all and gain a massive amount of precision.
- 7y ago
- gknoy 7y agoThis documentation is very impressive. I like that the author included a link to "Why is the documentation structured this way?" [0]. 0: https://www.divio.com/blog/documentation https://www.divio.com/blog/documentation
- aurbano 7y agoThat’s extremely well written! I’ve been struggling to document an open source platform I’ve built with some friends and colleagues [1] and this is finally giving me hope! [1] https://play.socialgorithm.org https://play.socialgorithm.org
- antcas 7y agoReminds me of https://www.handwrite.io https://www.handwrite.io
- Frodo478 7y agoWow, that's reminds me of Her (Spike Jonze)
- philpem 7y agoI remember a similar Mike Cook "Beeb Body-Building" article from Micro User. He used a similar layout and two potentiometers to build a "radius-arm digitiser". A little bit of calibration and some trigonometry and you can work backwards from the pot positions to Cartesian X/Y co-ordinates. A little bit more work and you can enter line points from a paper drawing into the rudimentary CAD systems which existed on the BBC Micro at that time.
- carapace 7y agoOoo! Combine this with a sand table, the arm draws in the sand w/ a stylus, and add a little vibration motor to "erase" the "screen".
- joquarky 7y agoSomeone at my local makerspace made something like this, but for vertical surfaces. https://github.com/brandonagr/gocupi https://github.com/brandonagr/gocupi
- panpanna 7y agoYours produces significantly better drawings. Sure, it uses more expensive step motors, but there are cheap versions of those too.
- jstanley 7y agoIt's a shame the repository doesn't have any examples of the pictures it's drawn. There are some on http://brandonagr.github.io/gocupi/ http://brandonagr.github.io/gocupi/
- deleted 7y ago[deleted]
- lukey_q 7y agoAwesome to see pen plotter stuff posted here with more frequency. This project is pretty amazing in its frugality, kudos to the author. I have another pen plotter and I'd highly recommend pen plotting to anyone who's into generative art or anything similar, it's really fun to write a few lines of code to generate some visuals and then watch the plotter as your design is made into something tangible. I'm working on a (free) app around making drawings on your computer, putting some effects on them, and sending them directly to a pen plotter. So far it only works with axidraw because that's the only one I have, but ultimately it's just sets of coordinates so it could be adapted for other plotters pretty easily. I'll post it here once it's in a decent state :)
- andrepd 7y agoI built a plotter with my now old mindstorms kit, the old RCX brick :) (just built and programmed, design was from lego).
- romwell 7y agoFWIW, every 3D printer is also a pen plotter (just stick a pen to your print head!). Here's my old faithful Printrbot plotting a dragon curve: Fountain pen, timelapse: https://www.instagram.com/p/BlQHk43gwra/ https://www.instagram.com/p/BlQHk43gwra/ Fountain pen, final image: https://www.instagram.com/p/BlJHawZgFi1/ https://www.instagram.com/p/BlJHawZgFi1/ Ballpoint, realtime: https://www.instagram.com/p/BlJ8dgmAaTA/ https://www.instagram.com/p/BlJ8dgmAaTA/
- aallen90 7y agoThat's awesome! What print speed did you use? (your steppers sounded like it was very high) And do you slice 1st layer normally?
- romwell 7y agoThanks! I didn't use a slicer, went straight into G-code for that one (wrote a program that generates the G-code for the dragon curve: a sequence of G0 commands). Don't remember what the feedrate was; with the pen attached tight, I could go pretty fast.
- DanieleProcida 7y agoSome more images of and by the plotter: https://www.dropbox.com/s/fuifujd70jvn7lw/brachiograph-images.pdf?dl=0 https://www.dropbox.com/s/fuifujd70jvn7lw/brachiograph-image...
- nmstoker 7y agoProduces a wonderful artistic effect! Great project Daniele!
- edge17 7y agoI like the layout of this site, what is being used to present the documentation on this site? Or is it a fully custom built site?
- swsieber 7y agoI think it's the standard https://readthedocs.org/ https://readthedocs.org/ standard. It's definitely not custom. I've seen many projects with it. Edit: Seems to be linked to the doc tool called Sphinx.
- bullen 7y agoIf you like this and have some dough: https://axidraw.com https://axidraw.com If you have less, google 4xidraw...
- allenu 7y agoReally cool hardware, but I wish there were a bunch of more photos of plots on the page! I want to see the output.
- DanieleProcida 7y agoThanks for all the interest and kind remarks this has received. I have updated the documentation substantially and included more photos in it.
- ashish01 7y agoI am a complete n00b at this but very interested in making a CoreXY plotter. I get struct at how to get parts like linear guides and servos needed for this. What is the best way to educate oneself about this. Is there something like sparkfun how mechanical hardware. Thanks!
- all2 7y agoMy goto while building a 3D printer is this: https://hackaday.com/2018/08/03/classy-corexy-build-breaks-down-the-design-pinchpoints/ https://hackaday.com/2018/08/03/classy-corexy-build-breaks-d...
- kareninoverseas 7y agoThis is great! Thanks for sharing.
- aleksgrach 7y agoI have never seen such a device, now I will tell the artists.
- deleted 7y ago[deleted]