Whenever I use the eggbot hatch extension, the eggbot can't keep it within the lines of the object it is supposed to be filling. The fill gets increasingly shifted to one direction during plotting, falling outside of the outline that was previously drawn.

Does anyone have an idea of how to fix this? I don't think that it has to do with the eggbot missing steps - I did an extremely long zig-zag/curly path that ended onto it's starting point and the eggbot executed and landed the end point perfectly.

Several things to consider.

1. See the improving precision page at the wiki as you are likely having some slippage,

http://wiki.evilmadscience.com/Improving_precision

2. I keep on meaning to update the Eggbot Contributed Hatch extension to do an "inset" hatch with a user-selectable inset amount (percentage). But, I haven't done that yet so that doesn't help you much. But you can try to achieve the same effect one of two ways: scale the outline a tad larger after hatching or scale the hatches a tad smaller after hatching. The latter is what you really want to do unless you don't mind the overall figure getting a tad larger.

To do 2, first generate the hatches. Then select the hatched object and ungroup it from the hatch lines with Object > Ungroup. Then select the hatch lines. (I drag the two apart so I can tell which I've selectede.) With the hatches selected, use Object > Transform. In the Transform subwindow, select the "Scale" tab. Check the "Scale proportionally" box. Then enter a percentage such as 99 or 98%. Click Apply. You will now have the hatches a tad smaller. Reposition them inside the figure if you moved them. Regroup the two together again if you wish.

However, if you are having plotting precision problems, doing an inset of the hatches will only help somewhat.

Dan