Positioning apparatus for tool sharpening

A positioning apparatus for positioning a workpiece having end cutting edges on an axial end face thereof in a workpiece holder having an end face from which the workpiece projects prior to a grinding operation, the apparatus comprising:

• a guide frame having a first, elongate guide bar with a guide slot extending along the bar to define a first adjustment direction;
• a mounting assembly for releasably supporting the guide frame on an end face of a tool holder with the guide bar projecting transversely away from the end face;
• a slide member slidably mounted in the guide slot and having a portion projecting transversely to one side of the slot;
• a levelling member secured to the projecting portion of the slide member and extending transverse to the guide bar, the levelling member having a levelling plate at one end having locating key means for seating against an end cutting edge at the axial end face of a workpiece to control the distance of said end cutting edge from said workpiece holder end face;
• releasable locking means for locking the slide member in a selected position in the guide slot;
• and
• adjustment means for adjusting the position of the levelling plate relative to the chuck in a second direction perpendicular to said first adjustment direction.

A method of positioning the cutting edges at the end of a tool mounted in a tool holder prior to a sharpening operation, comprising the steps of:

• securing the first part of a mounting assembly for mounting a positioning device on the end face of a tool holder to the end face in a level orientation;
• suspending a guide member forming part of the positioning device from the first part of the mounting assembly so that it projects transversely away from the end face of the tool holder;
• mounting a cylindrical pin in the tool holder, the pin having a flat diametrical cut out extending from one end;
• levelling the flat surface of the pin and tightening it in the holder in its levelled position;
• sliding a levelling member mounted in the guide member in a first direction towards and away from the tool holder, and sliding the guide member relative to the first part of the mounting assembly in a second direction across the end face of the tool holder until a key indent on the levelling member is aligned with the position of the flat surface;
• locking the guide member and levelling member in the aligned position;
• sliding the levelling member in a third direction relative to said guide member perpendicular to the first and second directions until the flat surface rests in said key indent;
• locking the levelling member in its adjusted position relative to said third direction;
• removing the guide member from the tool holder;
• inserting a tool to be sharpened in the tool holder;
• replacing the guide member on the holder;
• adjusting the extension of the tool out of the holder and rotating the tool in the holder until one of its cutting edges rests in the key indent;
• locking the tool in the adjusted position;
• removing the guide member from the tool holder;
• sharpening the positioned cutting edges.