Planar butt jointing techniques

[evansd2]

Here’s a better explanation of cut shape (or cut profile) with illustrations by @jules. Hopefully it can show why flipping one piece helps to make the edges mate cleanly.

Cutting the same shape twice

If I understand what you are asking about here, it’s the normal result of the shape of the cut profile with a surface focal point. A laser that is focused at the surface of the material does not cut (or burn in this case) straight up and down because it burns a little bit less farther away from the focal point, than it does right at the focal point. It’s an intensity and focus thing. So a side view of the cut edge looks like this at different focal points inside the material: [profile] And …