A central chuck including a chuck base, a first chuck and a first drill bit. The first chuck is rotatably coupled to the chuck base and has a chuck bore terminating at a lower chuck wall and a transverse locking bore. A locking plug is threaded into the transverse locking bore. The first drill bit has an upper portion, a central portion and a distal end. The upper portion has a smaller diameter than the central portion with a shoulder spanning between the upper portion and the central portion. An oblique plane defined in the upper portion inclined in a downward and inward direction toward the shoulder. Threaded insertion of the locking plug into the chuck bore interfaces with the drill bit and directs the drill bit in an upward direction and forces the shoulder into tight abutment with the lower chuck wall.