I’ve been plotting some large stipple files (i.e. 5000 to 10000 dots), but they always have cracks in them. At least it looks like a crack due to the incorrect position of some of the dots. These plots take anywhere from 45 mins to 1.5 hours to complete. They all look fins on the screen and I’ve wired with several different images all with similar results. I’ve also read the ‘Improving precision’ section of the wiki. The images are not full of these cracks, but there are always a few. Reducing the number of dots help, but that is most likely due to the loss of detail.
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.