Self-retracting tool

A tool holder assembly for mounting a tool on a machine in a predetermined location with respect to a workpiece to perform a machining operation on the workpiece, wherein the portion of the surface of the workpiece being machined and the work performing portion of the tool move relative to one another in a cutting direction and in a feed direction at right angles thereto, the tool holder assembly comprising:

• a base member adapted to be affixed to the machine;
• a tool holder having means for rigidly mounting the tool thereon;
• mounting means for pivotally mounting said tool holder to said base member for pivotal movement of said portion of the tool between first and second positions,
• said mounting means being operable to permit movement of said tool portion to said second position in response to the forces created by the engagement of said tool portion and the surface to be machined,
• the axis of said pivotal movement intersecting a plane which is parallel to said cutting direction and said feed direction and includes the point of engagement of said tool portion with said workpiece during machining;
• and
• stop means for limiting further pivotal movement of said tool holder when said tool portion moves from said first position to said second position.

A tool holder assembly for mounting a tool on a machine in a predetermined location with respect to a workpiece to perform a machining operation on the workpiece, the tool holder assembly comprising:

• a base member adapted to be affixed to the machine;
• a means defining a flat surface on said base member;
• a tool holder having means for rigidly mounting the tool thereon;
• means defining a flat surface on said tool holder;
• mounting means for pivotally mounting said tool holder to said base member with said flat surfaces slidingly engaging one another,
• said surfaces being inclined at an angle with respect to the longitudinal axis of the assembly;
• means defining a recess communicating with one of said surfaces;
• a stop member projecting from the other of said surfaces into said recess,
• said recess being larger than said stop member so that said stop member can move in said recess as said tool holder pivots with respect to said base member;
• and
• stop means in said recess adapted to engage said stop member for limiting said pivotal movement of said tool holder in one direction.