Worked as described, perfect holes in marble tile and cement board with little effort. The hardest part was guiding it [at an angle at first], but once it bites in and you straighten the bit, it only takes a minute. Provided you have adequate cooling and are letting the drill work at its own pace, don't apply much pressure or speed. I made a small "wall" of plumbing putty around the area I was cutting, filled it with water, and added more water as I drilled to keep it clean and cool.