Adapter enabling small draw-type collet to operate as stationary-type collet in large lathe spindle sleeve

A collet adapter for adapting a machine spindle to a small draw-type collet, the draw-type collet including a forward portion for receiving a workpiece and a rearward portion extending into the collet adapter, the machine spindle having an axially stationary outer portion including a cap nut and an axially movable sleeve inside the axially stationary outer portion, the collet adapter comprising:

• an adapter body having an inside surface and an outside surface, the inside surface configured to receive the collet in sliding engagement, the outside surface configured to be received into and to move axially with the moveable sleeve;
• and
• a restraining apparatus configured to transmit an axial force from the cap nut to the rearward portion of the draw-type collet to restrain forward axial motion of the draw-type collet whereby forward motion of the adapter body exerts a radially inward force upon the draw-type collet thereby operating the draw-type collet in an axially stationary mode wherein the adapter body has a rear portion sized to fit into the moveable sleeve and a forward portion configured to extend in a forward direction beyond the moveable sleeve to allow a workpiece to be gripped beyond the fixed portion of the machine spindle and wherein the adapter body includes a flared portion between the rear portion and the forward portion, the outside diameter of the flared portion increases in the forward direction, the flared portion is complementary to an inside surface of the moveable sleeve whereby engagement between an inside surface of the moveable sleeve and the flared portion compels forward motion of the adapter body.

A collet adapter for adapting a machine spindle to receive a small collet, the machine spindle having an axially stationary outer portion and an axially movable sleeve configured to move axially within the axially stationary outer portion, the collet adapter comprising:

• an adapter body having an inside surface and an outside surface, the inside surface configured to receive a collet, the outside surface configured to be received into and to move axially with the moveable sleeve;
• and
• a restraining apparatus configured to transmit a restraining force through the adapter body from a forward portion of the axially fixed outer portion of the spindle to a rearward portion of the collet to restrain axial motion of the collet during forward motion of the adapter body whereby forward motion of the adapter body closes the collet upon a workpiece while the collet remains axially stationary wherein the adapter body has a rear portion sized to fit into the moveable sleeve and a forward portion configured to extend in a forward direction beyond the moveable sleeve to allow a workpiece to be gripped beyond the fixed portion of the machine spindle and wherein the adapter body includes a flared portion between the rear portion and the forward portion, the outside diameter of the flared portion increases in the forward direction, the flared portion is complementary to an inside surface of the moveable sleeve whereby engagement between an inside surface of the moveable sleeve and the flared portion compels forward motion of the adapter body.

A collet adapter for adapting a machine spindle to a small collet, the machine spindle including an axially stationary outer portion and an axially movable sleeve inside the axially stationary outer portion, the axially stationary outer portion further including a cap nut, the collet adapter comprising:

• an adapter body having an inside surface configured to receive a collet and an outside surface configured to be received into the machine spindle sleeve whereby the adapter body is constrained to move with a forward motion of the spindle sleeve;
• a draw nut configured to couple to threads on an outside surface of the collet;
• and
• a plurality of thrust linkage rods each having opposing ends whereby a first end of each linkage rod transfers a force to the cap nut and a second end of each thrust linkage rod engages the draw nut thereby transferring a force between the draw nut to the cap nut to restrain axial movement of the collet during forward motion of the adapter body.