Quotecozmicray cut is NOT exactly square (90 deg) don't know why (perhaps focus off) Yes probably focus. I used to working with my CO2 laser with a replaceable focusing lens. Anyway, the beam should doing the same thing... The laser beam will converge then diverge: \ / X / \ If you are too close to the foam the cut will be wide at the top and narrow at the bottom. If you are tooby cpdude - Laser Cutter Working Group
I had a very similar thing happen with the same equipment--though it looks like I might have caught it a little quicker. I strongly believe it was caused by loose heated bed wires on the terminal block. Regards, Brianby cpdude - RAMPS Electronics