I give this tool 5 stars because it has worked well for me. But after a few projects (many hours of use) it started to shake due to poor storage. No wonder considering the way this tool is used, which is pressed against the material at 90 degrees to the axis of rotation with considerable pressure as it is passed over the material to be cut. Ok, I disassembled it and replaced 2 bearings and it's working again. FYI the bearings are standard 6004-2RS and 6203-2RS (top and bottom). Inexpensive and easy to exchange. Works well at 2000rpm. Either use a separate hose to run a large volume of water over the surface you are sculpting, or use this nozzle on a dedicated stone polishing tool with a built in water supply.