Self-centering steady rest for lathe

A steady rest for retaining a workpiece of a circular diameter and with a central axis, on a lathe, comprising:

• a housing;
• a pair of mirror symmetrical outer holding members each pivotally mounted by pivot mountings to said housing;
• each outer holding member having a contact end for contacting the diameter of a workpiece at a contact point, and a free end, said outer holding members, said pivot mountings and said housing undergoing an elastic deformation when said contact ends of said outer holding members are pressed against a workpiece by a chucking force;
• a central holding member having a longitudinal axis and mounted for linear motion to said housing between said outer holding members, said central holding member having a contact end for contacting the diameter of a workpiece at a contact point, said contact points of said holding members all being co-planar and being equally spaced around the diameter of a workpiece held by said holding members;
• an actuating piston operatively connected to said central holding member for moving said central holding member along its longitudinal axis toward a workpiece;
• an adjustment member operatively connected to said central holding member and movable along said longitudinal axis by said actuating piston, said adjusting member being movable relative to said central holding member along said longitudinal axis;
• and
• actuator means connected to said central holding member for moving said central holding member along said longitudinal axis relative to said adjusting member by an amount corresponding to the elastic deformation of said outer holding members, said pivot mounting and said housing which are a result of applying the chucking force on said actuating member by said actuating piston, said central holding member being non-rotatably mounted to said housing, said actuator means comprising a control member rotatably mounted to said housing and thread means operatively connected between said control member and said central holding member for moving said central holding member axially with rotation of said control member, said actuator means including an actuator connected to said housing and having a rotatable part connected to said control member, said actuator rotating said rotatable part by a selected amount corresponding to the amount of axial movement of said central holding member necessary to correspond to the elastic deformation, said control members comprising a rod with a step, said rod being slidably mounted parallel to said longitudinal axis on said actuating piston and said step being engageable with said actuating piston for transmitting linear movements of said actuating piston to linear movements of said central holding member and said adjusting member.

A steady rest for retaining a workpiece of a circular diameter and with a central axis, on a lathe, comprising:

• a housing;
• a pair of mirror symmetrical outer holding members each pivotally mounted by pivot mountings to said housing, each outer holding member having a contact end for contacting the diameter of a workpiece at a contact point, and a free end, said outer holding members, said pivot mountings and said housing undergoing an elastic deformation when said contact ends of said outer holding members are pressed against a workpiece by a chucking force;
• a central holding member having a longitudinal axis and mounted for linear motion to said housing between said outer holding members, said central holding member having a contact end for contacting the diameter of a workpiece at a contact point, said contact points of said holding members all being co-planar and being axially spaced around the diameter of a workpiece held by said holding members;
• an actuating piston operatively connected to said central holding member and movable along said longitudinal axis by said actuating piston, said adjusting member being movable relative to said central holding member along said longitudinal axis;
• and
• actuator means connected to said central holding member for moving said central holding member along said longitudinal axis relative to said adjusting member by an amount corresponding to the elastic deformation of said outer holding members, said pivot mounting and said housing which are a result of applying the chucking force on said actuating member by said actuating piston, said actuator means comprising a stop axially movable on said housing and engageable with said central holding member for moving said central holding member by a selected axial amount corresponding to the elastic deformation, and a rod mounted for axial movement to said housing and carrying said stop, said rod being mounted to said actuating piston at an axially adjustable location thereon.