In guitars and other stringed musical instruments, strings, typically of different diameters, are stretched across a bridge over a resonant box. The strings terminate on revolving pegs or stems on a headstock connected to the box. Each string is separately tuned to a note on an appropriate key by rotating the winder stem to adjust the string tension. In playing the instrument, the musician effectively alters the length of each string by pressing the string with a finger against a fret to shorten the string length and produce the vibrational frequency associated with the selected note.
In common usage, a musician from time to time encounters a broken or malfunctioning string, thus requiring a string change. If the old string is intact, it must be fully unwound before the new one can be installed. After selecting the new string, even if cut to an appropriate length, there is still considerable slack I which must be eliminated by winding the string around the string winder stem. Conventional winding tools are flat or disc-shaped and require a twisting motion of the thumb and forefinger. For many years, crank-type tools have been available to facilitate a somewhat easier twisting motion, thereby accelerating tightening or loosening the strings while they are being changed. Such tools have included handles rotatable relative to an arm, and an underlying receptacle to receive and grip the knob of the tuning machine. The tool is then cranked, thereby tightening or loosening a selected string.