April 12, 2014 at 8:00 pm #21502
Yes, something is mechanically shifting while plotting. We’ve seen similar “cracks” on long stipple plots, both on the EggBot and WaterColorBot, although usually not this frequent or large.
Check very well to make sure that everything in the pen arm is thoroughly tightened, and unable to slip. Check that the pen is held very securely in place, and check that the egg is also held very securely in place. You may also want to try a different pen. Once all the rest is secure, you will likely find the dominant source of this kind of “cracking” is the flexing of the “felt tip” part of a felt tip pen– if the pen is moving one way, it may bend differently than if the pen is moving in another direction.