I have never seen such a device, now I will tell the artists.
BrachioGraph – a cheap, simple pen plotter
101–109 of 109 posts
Re: BrachioGraph – a cheap, simple pen plotter
#102Earlier quoted context omitted.
A 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.
Be 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/ha...
I just assumed they were all terrible, maybe I've just been getting counterfeits this whole time. I'll have to check.
Where do you normally order from to guarantee originals?
Re: BrachioGraph – a cheap, simple pen plotter
#103Earlier quoted context omitted.
The line-us looks really good, the software also looks well put together.
Is it hackable?
It looks like people can code Scratch to control it...
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.
Re: BrachioGraph – a cheap, simple pen plotter
#104Earlier quoted context omitted.
A 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.
Be 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/ha...
Would a counterfeit be a problem for this particular application? Dont they still work?
Re: BrachioGraph – a cheap, simple pen plotter
#105It'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 qu…
I believe cheap servos are inherently very discrete due to noise in the "potentiometers" used: it will not be possible to do precise positioning no matter how exact your timing pulses are. But thats just a guess. If its a noisy potetiometer/wiper but monotonic it should be possible to correct in software. If its non-monotonic and has reverses gradient it will be much harder or impossible I guess.
Re: BrachioGraph – a cheap, simple pen plotter
#106Earlier quoted context omitted.
FWIW, 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/ Fountain pen, final image: https://www.instagram.com/p/BlJHawZgFi1/ Ballpoint, realtime: https://www.instagram.com/p/BlJ8dgmAaTA/
That's awesome! What print speed did you use? (your steppers sounded like it was very high) And do you slice 1st layer normally?
Thanks! 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.
Re: BrachioGraph – a cheap, simple pen plotter
#107Earlier quoted context omitted.
A 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.
Be 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/ha...
Awesome project!
Newer SG90 are described as a digital servo: http://www.towerpro.com.tw/product/sg90-7/
Should the older analog version (or perhaps a different part entirely?) be used for brachiograph? There's a note in the docs about analog servos being more suitable for this application.
Re: BrachioGraph – a cheap, simple pen plotter
#108Earlier quoted context omitted.
Be 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/ha...
Would a counterfeit be a problem for this particular application? Dont they still work?
Half of them break just assembling whatever you are building.
Re: BrachioGraph – a cheap, simple pen plotter
#109[deleted]