This is a good set if you just want to do some crafting around the house. I had them drill holes in some of the pots. I've had no problems with terracotta urns, but I've had thick china urns that they just won't cut, water or no water. I wanted to convert them into planters. Of course I bought another set of diamond tips beforehand to use on the same urns and they didn't cut any holes either. Husband says it's probably because I was trying to use a tool that was battery powered and unplugged…