Today I tried to cut balsa. First tried 4.8mm. After some tries I got to power 100% speed 10mm/s and 5 passes. On the table it says 5mm balsa should be cut in one pass. Even 1.8mm I have to make 2 passes 12mm/s. Do I have something wrong? I did focus the laser, and final cut on another side is pretty thin. What could be the issue?