Eggbot makes ugly graphics

[sni...@franksemi.dk]

Hello Group,

I made an Eggbot, this one ( http://www.thingiverse.com/thing:20398 )
http://www.thingiverse.com/make:53174

Only one problem, that I hope someone can point me in right direction with solving.

When plotting on eggs, it looks like no microsteps is used and it's getting rather bad quality, but the drivers, voltage, wires etc. should all be in order. I checked everything like 20 times.

I use 200 step per revolution motors, 1/8 stepper drivers. I replaced motors and stepper drivers to be sure that it is not the problem.

I also tried scaling up x10 a svg drawing before exporting to gcode - and setting the zoom level accordingly, no improvements there ether.

So I assume that the problem is somewhere in the firmware, can someone have a look and verify if there is a problem there.

http://sundog.dk/eggbot/SphereBot.html
http://sundog.dk/eggbot/StepperModel.cpp.html
http://sundog.dk/eggbot/StepperModel.h.html

Thanks

Cheers,
Frank

[sni...@franksemi.dk]

Oh perhaps I should mention that im using feeder.py to send the gcode.

[Dan Newman]

You might get better traction by posting either a comment on Zaggo's "spherebot" Thing
or in some forum apropos to Zaggo's work. This particular forum is oriented towards
the "original" Eggbot which (1) doesn't consume gcode, (2) uses the EiBotBoard, (3)
definitely uses uStepping, and (3) is typically driven from Inkscape using the Eggbot
extension set for Eggbot. Put differently, I'm far from certain that this particular
forum/group is frequented by folks familiar with the spherebot or its Arduino code
and how it interfaces to Pololu steppers.

As a side note, you do have to get the current/reference voltages adjusted correctly
with Pololus. Otherwise, you can get motion which appears to be very jerky/discrete
and thus look like there's no micro stepping. The current is so low that the opposing
currents cannot hold an intermediate position between natural steps and thus you get
no microsteps. This is not unique to Pololu's. So, be sure that you have the reference
voltages/currents correctly set for the stepper motors (will depend upon such things as
the resistance of the motor windings; the rated current of the motors, etc.). You
can often get by with just trying different values as long as you're careful to not
exceed any ratings.

Dan

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[bruce shapiro]

Truly awesome response, Dan. You are an Eggboteer treasure-- thanks
for all your efforts!

Bruce