I bought this drill along with some other SDS Max rock drills to install T-stands and 8x8 wood posts. I bought almost the whole set from 1/2" to 2" 1/2" and they are all designed to drill holes at least 16" deep. The drill I use is a monster with a 25 pound drill head. With those bits, the bedrock couldn't cope. For a T-post, I drilled a hole that was 2 1/2" in diameter and 16" deep. Depending on how hard the surface was, the whole thing took 1 to 5 minutes from start to finish. After drillingβ¦