These diamond drill bit tools do not need center pilot holes Center pilot drills are mostly for wood metal etc These bits can drill 1 to 1 1/8 in deep Shank sizes vary but the largest shank is 3/8 - common electric or rechargeable drills can be used Electroplated diamond coating will wear off if the tool gets too hot Never let your drill bit run dry Here is how you could use water to keep the tool cool: a- You can build a mini water dam around the hole with plumbers putty b- You can choose to spray water on the drill bit c- Or you can use running water to cool the drill bit EASY TO USE Center pilot drill bits are for wood metal etc; Here is how you can keep the drill bit on target: a- You can make your own guide out of plywood - plastic or even cardboard All you need is to keep the drill bit in place until it makes the initial marks b- You can start drilling at an angle with the edge of the drill bit making a C slot and then getting the drill bit up to vertical c- You can manually guide the drill bit with wet sponge Please use protective gear