And if you want a COTS replica with a bit more polish: https://www.line-us.com/
BrachioGraph – a cheap, simple pen plotter
21–30 of 109 posts
Re: BrachioGraph – a cheap, simple pen plotter
#22Nice 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)
Re: BrachioGraph – a cheap, simple pen plotter
#23This 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?
Re: BrachioGraph – a cheap, simple pen plotter
#24It'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…
precision and accuracy don't come from motors. Mostly it comes from rigidity and squareness of the assembly, the smoothness of the rods, the quality of the bearings. The steppers I work with are not really accurate or precise, mainly they just average out errors as long as you're doing roughly the same number of moves in each direction.
Interestingly, servos mean different things. The servos used here are cheap crap (but work well enough) but in the Real World, servos are actually more like steppers that have feedback based on absolute or relative positioning.
I am also intriguided by the "can cameras be used for realtime feedback" but I don't think they have enough resolution to determine accurate sub-mm movements.
Re: BrachioGraph – a cheap, simple pen plotter
#25Nice 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)
Turns, 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. 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.
Re: BrachioGraph – a cheap, simple pen plotter
#26It'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…
There are similar techniques used to self-correct 3D printing. You can actually license a system from NASA.[0]
Re: BrachioGraph – a cheap, simple pen plotter
#27It'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…
> (e.g. stepper motors instead of servos)
Servos are more accurate than steppers.
See: https://en.wikipedia.org/wiki/Servomotor#Servomotors_vs._ste...
Re: BrachioGraph – a cheap, simple pen plotter
#28This 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?
Can’t vouch for the quality but just searching for [diy plotter] yields plenty of results that look interesting.
Re: BrachioGraph – a cheap, simple pen plotter
#29It'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…
Something like the "Shaper Origin" ? but it's still not cheap
Re: BrachioGraph – a cheap, simple pen plotter
#30This 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.