... supports a percussion drill, drill rod assembly, and a centralizing drill rod support disposed between the percussion drill and a stationary forward end drill ... , JIS S20C, SAE1020, AISI1020, ASTM A106B, ASTM A53B, ST45, ST42.(2)Out diameter: hex.19mm, hex.22mm ,hex.28mm , hex.32mm ... hole drill bits are available. (1)Diameter: 38mm-70mm.(2) Shape; carbide 3-blade type, steel cross bit, carbide cross ...