Abstract: The present invention relates to grinding apparatus for grinding the hard metal inserts of rock drill bits, said grinding apparatus having a grinding machine carried on an support system that provides a feed pressure for said grinding machine during grinding, said grinding machine equipped with a grinding pin driven by motor to rotate about its longitudinal axis wherein the grinding cup is rotated at variable speeds and the support system provides a variable feed pressure.

Abstract: The present invention provides a grinding member (2) or connection to a drive connection member (3) to form 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 member having: a. a grinding section (4) having top (8) and bottom surfaces (10), a centrally disposed convex recess (7) formed in the bottom surface of said grinding section having the desired profile to be ground; b. a support section (9) adjacent the top surface (8) of said grinding section; c. means (13) to connect the grinding member to the drive connection member wherein the grinding member can be disconnected from the drive connection member when it becomes worn.

Abstract: A holder device for use in a motor driven grinding machine for grinding button bits. The grinding machine has an output shaft formed with an axially extending passageway for receiving a stem attached to and extending outwardly from a grinding cup. The shaft has interengaging drive means for driveably engaging the grinding cup to the free end of the shaft. An O-ring engages between the stem and the passageway for removably retaining the stem in the passageway.