A blade attachment-detachment assisting apparatus includes a nut rotating part having an engagement pin that engages with an engagement hole of a nut, a nut grip part that grips an annular groove of the nut, a housing that supports the nut rotating part rotatably by a predetermined angle, and a lock mechanism. The nut rotating part is capable of advancing and retreating, relative to the housing, to a protrusion position and a fixing position at which engagement between the nut grip part and the nut is kept, and is fixed to the housing with the intermediary of a spring. The lock mechanism includes an inside surface by which advancing and retreating of the nut rotating part are restricted through engagement of the nut rotating part with the housing when the housing is rotated in one direction at the fixing position to which the nut rotating part has been pushed.

A known rotary tool holder (10) comprises a rotary tool gripper (11) and a non-rotary part (16) presenting a flat front wall (18), the rotary tool gripper projecting from the flat front wall and comprising a shaft segment (15) having two shaft flats (12, 13). A kit to assist in the manual change of a tool from such a rotary tool holder comprises a forked holding element (20) provided with two fingers (22, 23) that are suitable to be fitted by their inside on the two shaft flats, and a locking plate (30) that comprises a recess (31) and is suitable to be fixedly mounted on the front wall with the recess facing it, said recess being configured to house the two fingers fitted on the two shaft flats when the locking plate is mounted on the front wall, the recess extending across the locking plate and being delimited by two steps (32, 33) against which the two fingers can be fitted by their outside.

A known rotary tool holder (10) comprises a rotary tool gripper (11) and a non-rotary part (16) presenting a flat front wall (18), the rotary tool gripper projecting from the flat front wall and comprising a shaft segment (15) having two shaft flats (12, 13). A kit to assist in the manual change of a tool from such a rotary tool holder comprises a forked holding element (20) provided with two fingers (22, 23) that are suitable to be fitted by their inside on the two shaft flats, and a locking plate (30) that comprises a recess (31) and is suitable to be fixedly mounted on the front wall with the recess facing it, said recess being configured to house the two fingers fitted on the two shaft flats when the locking plate is mounted on the front wall, the recess extending across the locking plate and being delimited by two steps (32, 33) against which the two fingers can be fitted by their outside.

A blade attachment-detachment assisting apparatus includes a nut rotating part having an engagement pin that engages with an engagement hole of a nut, a nut grip part that grips an annular groove of the nut, a housing that supports the nut rotating part rotatably by a predetermined angle, and a lock mechanism. The nut rotating part is capable of advancing and retreating, relative to the housing, to a protrusion position and a fixing position at which engagement between the nut grip part and the nut is kept, and is fixed to the housing with the intermediary of a spring. The lock mechanism includes an inside surface by which advancing and retreating of the nut rotating part are restricted through engagement of the nut rotating part with the housing when the housing is rotated in one direction at the fixing position to which the nut rotating part has been pushed.

A chuck key for tightening the jaws of a drill chuck of a chuck is disclosed. The chuck key includes, a pin for engaging the chuck, a gear having a plurality of cogs arranged concentrically around a central axis for engaging cogs of the chuck, wherein the gear includes a cavity having a same center of axis as the gear, a protrusion opposite the pin, wherein the protrusion includes an aperture.