Abstract: Embodiments provide apparatuses and methods for excavation and drilling, particularly reverse circulation hammers and bits. Reverse circulation hammers and bits manufactured in accordance with various embodiments may help to prevent fatigue and breaking of the bit during a drilling operation, may prevent clogging of return holes, may provide higher efficiency drilling operations, and may provide modular bit designs that may be interchanged to suit a particular drilling operation.

Abstract: Embodiments provide apparatuses and methods for drilling and underreaming, particularly to underreamer expansion bits. Underreamer drill assemblies and underreaming bits manufactured in accordance with various embodiments may help to resist over-excavating or undermining, which may result in a more stable bore hole.

Abstract: A drilling apparatus comprises a casing shoe, ring bit, and center bit. The casing shoe may be connected to a casing received within the casing shoe. The ring bit is received within the casing shoe and retained at the end of the casing. The ring bit rotates relative to the casing shoe, and drills a peripheral portion of a hole. The center bit drills a central portion of the hole, and may be rotated and percussively driven to drill the hole. The center and ring bits are adapted for: engaging one another so that rotating and percussively driving the center bit also rotates and percussively drives the ring bit; engaging one another so that retracting the center bit also retracts the ring bit, casing shoe, and casing; enabling disengagement from one another and withdrawal of the center bit from the ring bit and the casing shoe.