Most accurately centering on Lathe can be done by

Collet chuck

• These are small chucks that fit into the headstock spindle and are used for holding bar stock (long bar or rods).
• These chucks are particularly useful in cases where accurate centering and quick setting are required.
• A collet is a hardened steel sleeve having slits cut partly along its length.
• It is held by a draw-bar which can be drawn in or out in the lathe spindle.
• The collet is guided in the collet sleeve, and held with the nose cap.
• It is possible to change the collet for different cross-sections depending on the cross-section of the raw material.

Three-jaw chuck

• It is also known as self-centering chuck or universal chuck.
• This chuck is used for holding round, hexagonal or other regular shaped work-piece.
• The work is centered automatically because all three jaws move forward or backward by an equal amount when the chuck is adjusted.

Four-jaw chuck

• Here each jaw may be adjusted independently and this chuck is particularly suitable for a heavy and irregular shaped workpiece.

Magnetic chuck

• These chucks are used for holding very thin workpieces which cannot be held in an ordinary chuck.
• They can also be used when the distortion caused by the jaws of an ordinary chuck is not desirable.

Mandrel

• A mandrel is used for holding and rotating a workpiece that has a bore in it.
• The mandrel is mounted between centres and the workpiece rotates with it.

Face-plate

• Face-plate is circular plates which can be fitted by screw threads to the nose of the lathe spindle.
• Face-plates have slots on them holding work by bolts and clamps.

• They have two plane surfaces, machined perfectly flat and at right angles.
• They have ribs on the unmachined part for good rigidity and to prevent distortion.
• It is a work-holding device used as a fixture in metalworking.