A core drilling system is disclosed herein in which a torque tube has a groove or keyway which receives a rotating wheel or key to prevent a transmission box and motor from rotating during drilling operation. As such, the operator does not need to hold a stabilizing arm to resist counter rotational forces during the drilling process. The operator may focus on the hole to be cut in a substrate. Additionally, a torque tube stabilizing leg assembly may be secured to the free distal end portion of the torque tube.