Grinding tool for buttons of a rock drill bit

A grinding cup for grinding the hard metal inserts or working tips of drill bits (percussive or rotary), tunnel boring machine cutters (TBM) and raised bore machine cutters (RBM) to restore them to substantially their original profile, said grinding cups having a lower grinding section and an upper body section connected to form a grinding cup having top and bottom surfaces, a centrally disposed convex recess formed in the bottom surface having the desired profile to be ground, one or more passageways in the upper body section and grinding section to permit a coolant to be provided to one or more outlets on the bottom surface, drive means provided on or in the upper body section that cooperates with the output shaft of a grinding machine, retaining means provided in conjunction with the drive means for detachable connection of the grinding cup to an output shaft of the grinding machine during use wherein the drive means and the upper body section or grinding section of the grinding cup are adapted to optimize the engagement surfaces and points of contact, directly or indirectly, between the drive shaft and the grinding cup to reduce negative impact on operational stability and rotor wear and wear to the grinding apparatus caused by vibration and resonance.