One of my stepper motors glitched or something, that's why the one eye is messed up. I think possibly one of my gears is a little loose on the stepper or something. My first drawing that I created from the beginning!

This is known as a TSP problem. Traveling Salesman Problem. Single line, doesn't cross itself (except mine did when the stepper glitched). Because I don't have a servo on my gondola yet, I thought this might be fun to make an image without lifting the pen.

Hi Sandy and others,

I'm running into a problem with jitter. As you can see in my smiley drawing above, one of the steppers seems to have glitched or something, and thrown off that side of the drawing.

My current setup, I'm using an Arduino Uno with a cheap ebay motor shield. I just have a 9 volt battery hooked up to the motor shield, and the Uno is just currently powered off the USB connected to the computer.

When I open the polar graph controller program, and just try moving the gondola up and down my paper via the program, I notice the glitching. One of the steppers will vibrate and kind of make a noise that's not normal. It stops spinning, hums/vibrates until the 'move' is complete.
I tried this on the three latest versions of the software and still see the problem, so I don't think its software related. Unless I have a config problem that's causing it.

I'm not sure why I was able to complete a couple drawings initially without problems, and now they are doing this. I was wondering if you had any tips on what may be causing this?

I guess I could try replacing my 9 Volt battery. I'll also remeasure everything and check all my config settings. I thought it was a loose wire, but I secured everything and am still experiencing this glitching.

It almost seems like it does it on long pen moves. I suspect maybe that means its a power issue, because that would be when it draws the most amps? I think my wire is 18 gauge, so I don't think that's the problem.

Do you think I need an official Adafruit motor shield or something? If this didn't work right off the bat, I would say yes to that....but I was able to draw the nautilus fine before.

Actually, looking back at my drawings, I think it might have been glitching all along. I noticed that the edges of the drawings don't line up correctly in my tree drawing.
I have saw tooth lines too on some, and others are nicely squared off.

This is going to drive me nuts trying to figure out!

Got it, I put in an order for some Adafruit 9v 1 amp power adapters.

Do you recommend that I hook an adapter to the motor board AND the Arduino (2 of them), or just the motor board? This is for an UNO that will be sent commands from the PC

ok, cool. Thanks for the tip!
So if I want to try plugging the power into my Arduino, keep the jumper in place?
And if I want to wire it directly to the motor shield, remove the jumper?

I really hope this fixes the problems I'm having. Otherwise, I might have to spring for an official Adafruit motor shield. I'd rather put that money towards a Mega for standalone operations!

Thanks for the tip Sandy! It appears that the power supply was my fault. I received my wall adapters from Adafruit and wired it up. I no longer see any jitter. I haven't made a drawing yet, but I did sort out the issue I was having with my setup drawing stuff 'backwards'. ie....when the pen would go left on the computer screen, the pen on the paper would go right.

I didn't think it was a big deal, but I wanted to do a drawing with some text. Text can't be backwards 🙂

I rearranged the wiring where it connects to my Arduino and that sorted it out.

I also had to change my counter weights just a little. They were too long, and bottoming out on my desk. Now they hang at an angle, so if they do hit the desk, they will fall flat, instead of standing on the bolt head.

I was going to comment on this - I had the exact same problem with my polargraph, I made the counterweights too long, and they were bottoming out. Shame I'm 3 years too late to impart any wisdom!