Multi-radial shaft for releasable shaft holders

A shaft for use in combination with a shaft holder having a generally cylindrical bore with an axis and a radius, the shaft comprising:

• a working end having a centerline;
• an insertion length of the shaft comprising a length of the shaft to be inserted in the bore;
• a circumference on a section plane normal to the centerline along the insertion length of the shaft;
• the circumference comprising a series of arcs in a sequence, including a first arc having a midpoint, each arc meeting the next arc in the sequence at a common endpoint of the two arcs;
• each common endpoint forming a slight ridge along the insertion length of the shaft;
• a clamping pressure point on the circumference at approximately the midpoint of the first arc;
• an opposite point on the circumference that is opposite the pressure point on a line from the pressure point through the centerline;
• a first two of the ridges flanking the pressure point and having a distance from the centerline that is less than the radius of the bore;
• and
• a second two of the ridges flanking the opposite point and having a distance from the centerline equal to the radius of the bore;
• whereby when the shaft is inserted into the bore and clamped in the holder, the first two of the ridges provide clearance, and the second two of the ridges contact the bore, causing the centerline of the shaft to be precisely coincident with the axis of the holder.