Abstract: A shaft-equipped grinder used in a mold-graving device, including a grinding member with a circular periphery and a shaft fixed on the grinding member. The shaft has a driving section with none circular cross-section, a locating section with circular cross-section and a stopper section formed as an annular groove. The grinder can be easily and quickly assembled with or disassembled from the mold-graving device. Also, the grinder can be accurately located on the mold-graving device coaxially with the rotary shaft thereof.

Abstract: An air die grinder secured on a rotary shaft of a pneumatic motor by a fixing device is disclosed. The fixing device includes a sleeve having a driving section with none circular cross-section and a locating section with a circular cross-section. A ball hole is formed through the wall of the locating section of the sleeve. A steel ball is placed in the ball hole and pushed by an outer tube fitted around the sleeve to protrude out of the inner wall of the sleeve and abut against the stem of the grinding wheel, therefore the grinding wheel is located on the die grinder.