Arcuately Spaced Reamer Cutting Heads for Directional Drilling

The boring operation is divided into multiple sequential steps using a series of boring heads with progressively larger diameters. Instead of using one large boring head that creates excessive twisting forces, the process uses multiple smaller boring heads in sequence, each enlarging the bore slightly. This segmentation reduces the twisting force at each step while maintaining the ability to drill through hard materials and stay on a straight path.

A pilot hole is drilled first to establish the initial bore path through the hard materials. This preliminary action creates a guide path that subsequent larger boring heads can follow, ensuring they remain on a straight trajectory. By pre-establishing the path, the multiple sequential boring operations can proceed efficiently without deviation, reducing the time loss that would otherwise result from correcting off-course drilling.

Each boring head in the sequence is designed with universal functionality to perform multiple tasks: cutting through hard materials, self-guiding along the pilot bore path, and enlarging the bore to a specific intermediate diameter. This multi-functionality allows a single boring head design to handle various stages of the enlargement process, reducing the overall complexity despite multiple operations being required.