Hi Steve, yeah that's pretty weird when that happens, isn't it!

I don't know if you saw the other recent discussion about offsetting here: http://moi3d.com/forum/index.php?webtag=MOI&msg=5680.3 - but it's related to that curvature continuous extension method. The way that extension mechanism works is by a sort of reflection of the curve around it's endpoint. If it extended it by a lot it sort of reflects the curve making that kind of repeated pattern on it, and then if it couldn't figure out how to trim them that's how you end up with such things remaining in the output.

If you use the round corners option, the offset pieces are not extended in this curvature continuous way to try and make them meet at a sharp point, instead they have the gap between them filled in by an arc segment and not any extensions done. So that's why that option avoids that.

I think it's some kind of bug in the extension mechanism where it's basically extending it by too large of an amount, it's on my list to look into in more detail at some point.

Maybe another reason though to have an an option for choosing between different sharp corner styles - either curvature continuous or straight line extensions, the straight line extension does not end up with that kind of thing in it.

- Michael