Shank attachment device

A shank attachment device configured to attach a drill to a rotating portion of a drill device and comprising an arbor and a shank, the arbor being detachably attachable to the rotating portion, the arbor and the shank being detachably attachable to each other, and the shank being detachably attachable to the drill, wherein:

• with the shank attached to the arbor, a stopper member disposed on the arbor engages with a stopper groove formed on a side surface of the shank to stop a movement of the shank in an axial direction away from the arbor;
• a first engaging portion formed on the arbor engages with a first engaged portion formed on the shank to enable a rotational torque of the arbor to be transmitted to the shank;
• and the shank contacts the arbor to stop the movement of the shank in the axial direction toward the arbor;
• the arbor includes an attachment shaft attached to the rotating portion of the drill device, an enlarged diameter portion is formed at a tip end portion of the attachment shaft, and the enlarged diameter portion is detachably coupled to a base body of the arbor by a screw;
• the shank is configured to be detachably attached to a shank attachment hole formed on the arbor;
• a center drill attachment hole communicated with the shank attachment hole is formed on the base body of the arbor;
• a fixing screw hole including an internal screw on an inner peripheral surface thereof is formed to extend from an outer peripheral surface of the base body to a center of the center drill attachment hole in a direction perpendicular to the center drill attachment hole;
• a fixing screw threadedly engages with the fixing screw hole such that a tip end thereof is able to project into the center drill attachment hole;
• and
• the enlarged diameter portion covers from outside at least a part of the fixing screw, which threadedly engages with the fixing screw hole, to prevent the fixing screw from falling out to an outside of the base body.