Okay, before you read any further, take a moment to click here and vote for my PlotterBot for the Road to Maker Faire Challenge.
Vote for our future. Vote PlotterBot!
I’ve been blogging about every little aspect of my own drawing robot – with this post1 it’s more than 80 posts on the topic. ((Photo courtesy of Vox Efx)) Everything from a list of other robots, to where I sourced the parts, to my failed attempts at designing parts, and a lot more posts about what I’ve done that does work. Using what I’ve learned from my own really colossal failures and the brilliant open source work of others like Sandy Noble and Dan Royer, I’ve designed all of my own printable plastic parts from scratch, explained my thoughts and considerations behind the designs in excruciating detail, and shared all the files and my source code for everyone to use.
The winner of Maker Faire’s contest “The Road to Maker Faire Challenge” gets $2,500.00. Dear gentle reader, should I be fortunate enough to win – I hereby make you these two promises:
- I promise to spend every last dime on building more and better robots.
- I promise to continue blogging relentlessly about what I did, how I did it, what worked, what didn’t work, and how you do it all yourself too.
So, please vote for my PlotterBot for the Road to Maker Faire Challenge!
- Which really doesn’t count… [↩]
I just voted for you. I like what you did with the paper roll, that was innovative. So much more compact than my method. I noticed the yoda picture has some “cracking”. Check your bobbins are on good and tight. Once I started using milled bobbins and perfect machanical fit the cracking disappeared.
@That Dan: Thanks for the vote!!! I’m glad you like the paper roll system. So far it has worked out just as well as I had hoped for. It’s easy to draw something, rip the paper off, can get to work on another drawing right away.
The bobbins I’m using are printed spools comprised of two plastic parts held together by two bolts and two nuts. Once assembled, I slide it onto the motor shaft and tighten down another bolt and captive nut directly onto the flat part of the shaft. I can’t be positive, of course, but I’m pretty sure the spools are really really secure.
The “cracking” you see is from me futzing with the robot as it was drawing – exactly like you’re not supposed to. :) That and I may have been moving my ‘bot too fast. And, I was using a pen holder that consisted of a pen, four AA batteries, cardboard and held together by hot glue and really hard wishing.
The cracking means the string length has changed in an unexpected way. The only time I’ve ever seen was (a) motor lost steps or (b) bobbin was slipping. (A) has a lot of potential reasons – software mistake, electrical power, low motor torque/pen weight ratio. Your pen holder sounds fine. Since your bobbins aren’t the issue it has to be something else. Is the string wound on your bobbin in a really wierd way? I always let the machine do it for me.
@That Dan: Lost steps is a definite possibility. I think for that drawing (besides using a crap pen holder) I was also running the ‘bot at roughly 1.5 times the default speed and 2.0 times the default acceleration. If I recall correctly, I may have turned the pots down at the same time to reduce motor noise. A slow drawing, with slow acceleration, and low pots might not be so bad.
I suppose it could also be the string. The spools are mounted directly above the filament guide, so that the filament winds/unwinds roughly along the center core of the spool. The spool has a wide diameter (I think nearly 30mm?) which means that there shouldn’t be too many wrapped layers causing distortion. However, it’s entirely possible that it wound/unwound badly at some point. The spools are also mounted very close to the filament guides – to help prevent tangles.