Abstract: There are provided an expanded hole drilling device, a component for the expanded hole drilling device, and an expanded hole drilling method, capable of expanding the diameter of a previously bored hole to a large diameter without causing decentering. The expanded hole drilling device 10 includes a drill holder 22 that is attached to a drill grasping part 18 in place of a drill 16 and grasps the drill 16, and a centering attachment 24 having a conical tip end part, which is attached to the drill holder 22. The expanded hole drilling method includes a step of arranging a bored workpiece displaceably on a table 14, a step of performing centering by inserting the tip end part of the centering attachment 24 into a bored hole, a step of fixing the centered workpiece on the table 14, and a step of drilling the workpiece to expand the hole by using the drill 16 after the centering attachment 24 has been removed.

Abstract: There are provided an expanded hole drilling device, a component for the expanded hole drilling device, and an expanded hole drilling method, capable of expanding the diameter of a previously bored hole to a large diameter without causing decentering. The expanded hole drilling device 10 includes a drill holder 22 that is attached to a drill grasping part 18 in place of a drill 16 and grasps the drill 16, and a centering attachment 24 having a conical tip end part, which is attached to the drill holder 22. The expanded hole drilling method includes a step of arranging a bored workpiece displaceably on a table 14, a step of performing centering by inserting the tip end part of the centering attachment 24 into a bored hole, a step of fixing the centered workpiece on the table 14, and a step of drilling the workpiece to expand the hole by using the drill 16 after the centering attachment 24 has been removed.