Fool-proof tool coupling having axially spaced apart drive members and assembly method therefor

A tool coupling (20) for a rotary cutting tool (68), the tool coupling (20) comprising:

• a first member (22) and a second member (24), the second member (24) being coupled to the first member (22),
• the first member (22) having a male coupling portion (26) extending along a first axis (A1) in a forward-to-rearward direction (DF, DR),
• the second member (24) having a female coupling portion (32) extending along a second axis (A2) coaxial with the first axis (A1),
• the male coupling portion (26) having a front drive member (28) located axially forward of a rear drive member (30), the male front and rear drive members (28, 30) defining front and rear footprints (FG1, FG2) in respective first and second transverse drive planes (PTG1, PTG2) perpendicular to the first axis (A1) and intersecting the front and rear drive members (28, 30),
• the female coupling portion (32) having axially spaced apart front and rear drive passages (34, 36), the front and rear drive passages (34, 36) defining front and rear peripheral profiles (FD1, FD2) in respective first and second transverse passage planes (PTD1, PTD2) perpendicular to the second axis (A2) and intersecting the front and rear drive passages (34, 36),
• wherein:
• the front and rear drive members (28, 30) simultaneously occupy the front and rear drive passages (34, 36), respectively,
• the first transverse drive plane (PTG1) and the first transverse passage plane (PTD1) are coincidental;
• the second transverse drive plane (PTG2) and the second transverse passage plane (PTD2) are coincidental;
• during imaginary rotation of the front peripheral profile (FD1) by 360 degrees about the second axis (A2), the front peripheral profile (FD1) overlaps the front footprint (FG1) when viewed along the second axis (A2),
• during imaginary rotation of the rear peripheral profile (FD2) by 360 degrees about the second axis (A2), the rear peripheral profile (FD2) overlaps the rear footprint (FG2) when viewed along the second axis (A2), and
• at least one of the front and rear drive members (28, 30) prevents rotation of the second member (24) about the second axis (A2) relative to the first member (22),
• and wherein:
• upon imaginary axial projection of the front peripheral profile (FD1) onto the second transverse drive plane (PTG2), and imaginary rotation of the front peripheral profile (FD1) by any angle about the second axis (A2), the front peripheral profile (FD1) always overlaps the rear footprint (FG2) when viewed along the second axis (A2).