I was at the laser last night and met with two disasters. I was trying to cut the second half of my 3rd frame, hopefully the final version, my "1.0". The first problem was knotty wood. The middle ply must have had some flaws because it wasn't cutting all the way through and was giving off some black soot (pictured). Not ruinous though, I just had to do a few extra passes. The next problem though, was a doozy. The encoding strip got dirty and the laser started rendering my precise lines and curves as ragged sawtooths and blobs. So after 45 minutes of work, that board was now kindling.