Used to make cuts in pine boards for a picture frame. I used the thinnest nozzle. No break so far. Fairly precise and clean cut. I haven't tried other types of wood yet, e.g. hard rocks. However, I have followed general online advice on what speed to use based on drill bit diameter to avoid splitting or damaging the drill. It really helped. My typical Dewalt router uses 2 speed settings on pine. Smooth and stable control. On a 30" board forming two slots with only 1/8" bit spacing, the bits worked amazingly well. I think the company would get 5 stars if they included a few more of those good spacers for more bit separation.