What is the best way to increase accuracy of such servo motor ?
BrachioGraph – a cheap, simple pen plotter
41–50 of 109 posts
Re: BrachioGraph – a cheap, simple pen plotter
#42What is the best way to increase accuracy of such servo motor ?
harmonic gearbox
Re: BrachioGraph – a cheap, simple pen plotter
#43What is the best way to increase accuracy of such servo motor ?
Buy 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.
Re: BrachioGraph – a cheap, simple pen plotter
#44What is the best way to increase accuracy of such servo motor ?
Better 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.
Re: BrachioGraph – a cheap, simple pen plotter
#45This 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?
I've seen plotters made out of old CD drive parts.
Re: BrachioGraph – a cheap, simple pen plotter
#46It'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…
Replace large "cheaper servos" with a human and a self correcting small servos and you sot of have this:
Its very cool...
Re: BrachioGraph – a cheap, simple pen plotter
#47What is the best way to increase accuracy of such servo motor ?
Better 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 nee…
Also 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.
Re: BrachioGraph – a cheap, simple pen plotter
#48This 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?
I haven't looked to far into this project, you might be able to gain a decent amount of stability with better materials like 3d printed plates instead of cardboard. (This is a place where CF filament actually makes sense, it's one of the most rigid printable plastics)
Re: BrachioGraph – a cheap, simple pen plotter
#49This documentation is very impressive. I like that the author included a link to "Why is the documentation structured this way?" [0].
Re: BrachioGraph – a cheap, simple pen plotter
#50Reminds me of https://www.handwrite.io