Has anyone had this problem? I own a OLM3 with an LU3-20a 20w laser module. I had to change out the mirror lens and now I am get what I call burn back, lots of scorching on the front and soot on the back of my basswood. I have checked to distance, with and without air assist. exhaust fan on. The wood is elevated off the honeycomb.
Maybe try lower power & more passes. or could the speed be too slow.