Patent ID: 8256536

Claim:
A backreamer including a distal end configured for connection to product and a proximal end configured for attachment to a distal end of a drill string, the backreamer comprising: a backreaming cutter having a cutting side that faces toward the proximal end of the backreamer; a proximal assembly that extends between the proximal end of the backreamer and the backreaming cutter, the proximal assembly defining a vacuum passage for removing material cut by the backreaming cutter; a drive stem for transferring torque to the backreaming cutter for rotating the backreaming cutter, the drive stem being rotatably supported within the proximal assembly such that the drive stem and the backreaming cutter are rotatable relative to the proximal assembly; and a distal assembly that extends between the backreaming cutter and the distal end of the backreamer, the distal assembly including a vacuum blocking plate positioned distally with respect to the backreaming cutter, the backreaming cutter and the drive stem being rotatable relative to the vacuum blocking plate, wherein a distal side of the backreaming cutter is configured to scrape material from a proximal face of the vacuum blocking plate.