Undercutter attachment

An undercutter attachment for a machine tool for operating on a rotating workpiece comprising:

• a base;
• feed means for providing relative movement between said base and said workpiece;
• a movable toolholder pivotally mounted on said base by means of a pivot pin;
• a tool carried by said toolholder for cutting said workpiece;
• actuator means for engaging said tool in the cutting position in response to one direction of feed movement and holding said tool in said cutting position over an extending length of feed movement and disengaging said tool in response to return feeding in the opposite direction;
• said actuator means comprises a pivotally mounted activating arm, a cam surface on said arm, a follower on said pivotal toolholder, and stationary cam power means on said machine tool for moving said activating arm to in turn actuate said tool, said toolholder and said activating arm being mounted for pivotal movement about parallel axes normal to the axis of said workpiece;
• and
• positive latching means for securely fixing said tool in the cutting position, said actuator means including release trigger means for disengaging said latching means, said trigger means being movable in response to said cam power means.

The method of undercutting a rotating workpiece on a machine tool in order to form an undercut portion upon said workpiece relative to an enlarged diameter portion of said workpiece comprising the steps of:

• relatively feeding in one direction a cutting tool axially with respect to said workpiece,
• maintaining said tool at an inoperative position out of the path of said workpiece so as to avoid cutting over an enlarged diameter length of said workpiece,
• moving said tool in a single step from said inoperative position to an operative undercutting position against said workpiece after passing said enlarged diameter length in response to said movement,
• continuing to feed said tool relative to said workpiece so as to provide an extended undercut,
• relatively return feeding said workpiece and said tool in the opposite direction, and
• disengaging said tool in a single step from said operative undercutting position to said inoperative position during return feeding in response to said movement.