The pen arm should *not* bounce off of the headstock or tailstock in proper operation.
The available range for the pen arm can vary from about 600 - 1200 Inkscape "pixels," depending on a variety of factors including:
- The size of the object
- The configuration of the pen arm
- The type of pen
- How carefully centered the pen arm is at the beginning of the plot
- The aspect ratio used (how high the motor is located in its slot).
Generally speaking, one needs to start with the pen arm centered carefully, and adjust the size of the drawing that is plotted to ensure that it "fits" within the available range. If your drawing is much over 800 pixels tall, the most likely cause of bumping against the wall is that the drawing is too large.
If you still get bumping with files that are known to fit on an Eggbot (e.g., our example files), on a normal chicken egg, with a normal pen and normal pen arm configuration, then it is possible that there is a hardware defect that is causing the step size to be too large. To test this, remove the pen arm from the pen arm backer using the big thumbscrew. Leave the pen arm backer on Motor 1.
Make a new drawing that consists only of a single square, 800 pixels tall. Start with the pen arm backer vertical and begin plotting. The pen arm backer should (during the course of plotting) turn 45 degrees right of center and 45 degrees left of center-- 90 degrees total. If it does, then the Eggbot is operating correctly.
If the pen arm backer moves 180 degrees (90 degrees in each direction) instead, then it's likely that there's a glitch on the EBB that will need to be repaired. If this is the case, or if it moves some other amount, then you might try adjusting the current setpoint-- a bad current setting can sometimes cause steps to be skipped.
Windell H. Oskay