Pen starts down / Odd servo behavior

I've pieced together an Eggbot from various electronics I already had (Arduino Mega 2560 / Ramps 1.4) and everything seems to work well apart from the start.

The pen lowers to the egg, then travels to the starting position before beginning to print. This leaves a straight line from the home position to the start (see this link for an example: https://imgur.com/a/BU3vS). After that, everything prints fine. I'm unsure if this problem is due to my electronics setup or my software setup.

Any thoughts?

Software:
- Windows 10
- Inkscape 0.91
- Eggbot Extension 2.7.1

Hardware:
- Arduino Mega 2560
- Ramps 1.4
- SG90 Servo
- 17HS19-2004S Steppers

Comments

  • Really couldn't say. The EggBot software doesn't support RAMPS, so you're probably not using the EggBot extension per se, but something else altogether.

  • Thanks for the quick reply. I understand I'm not using the normal hardware, so I greatly appreciate the help. I downloaded the extension from this website, but the arduino side is from the Sphere-o-bot website.

    I'll take the ramps board out of the equation and try it again. Is there any arduino-based solution that is officially supported or just the EBB driver board?

    Like I said, thanks again for the "unsupported" help.
  • No, there isn't an official Arduino firmware for EggBot. You might see if the authors of that software have (for example) a github issues page that you can ask for help on.

    Alternately, if this is the standard extension (just with Arduino firmware on the receiving end), you could edit it to add an extra pen-up command before it starts the pen-up move to the start position.

  • Just to let others know if they pass this way. I was able to somewhat fix the problem using Windell's advice. I added:

    self.bPenIsUp = False
    self.penUp

    to the beginning of the recursivelyTraverseSvg function in the eggbot.py file (~ line 482). For some reason the pen still lowers initially before rising and going to the first position and continuing as normal. Can't figure out what is causing it to lower in the first place. But for now I just put a piece of paper underneath the pen as it lowers initially and that keeps it from leaving a mark. Wonder if I can debug the extension as it runs in Inkscape...
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