As another user said the drill just screws onto the mandrel and as it is carved the whole blade keeps spinning very quickly when the drill stops turning to move due to the heavy weight and come off completely. Having a large rotating sheet flying through the air over a project is not ideal. I really need to design it to snap onto the shaft like my other saw set. Unfortunately I had to buy these for a project. It works, but you have to be overly careful when using it. Be sure to wear gloves.