So far I have used two attachments out of four. I found that the Thor collet that holds the bearing in place had a loose socket head cap screw and the collet came loose causing the bearing to fall off during use. I checked all four bits and found that they all need to tighten the Allen collet screws. This is not a product quality issue and many operators double check their equipment before using a tool. Just upside down. A good tool, perfectly cuts wood and chipboard.