I'm not afraid to admit my mistakes. I've had tons of mistakes and I'm just starting;) Mistake 1, not tightening the collet nut, which lets the bit slide down while working. This happened a few times. I finally bought the correct collet wrench and that problem went away. Mistake 2, using the wrong parts to bolt down the stock. This made things really loosey goosey and ruined several stock blanks doing this. Also broke a bit. Mistake 3, not defining the limits of the top and bottom. That broke a couple bits. Now once I defined all that, things have been good. 12 panels no issues for me. I'm sure I'll have more mistakes in the future though;)