The main function of a lathe is to turn cylindrical shapes. Power is transmitted from the electric motor to the spindle by belts, pulleys, and gears.

The size of a lathe is determined by the largest diameter which can be turned over the bed and the greatest length which can be held between centers. Five main parts of a lathe include the headstock, gearbox, carriage, tailstock, and bed.

The top of the lathe bed contains special alignment tracks called ways. The head stock is on the left side of the bed and contains the spindle to which the lathe chucks or the faceplate can be attached. It also contains the gear box where speeds and feeds can be changed.

The tailstock on the right side of the bed can be used to support one end of the workpiece, or can be used for drilling, reaming or tapping in the lathe.

Work Holding Devices

Turning Between Centers A solid dead center is placed in the headstock. A live dead center is placed in the tailstock. This center has a bearing in it, allowing the center to revolve with the work.

Work turned between centers must have a center hole drilled in each end of the workpiece. A lathe dog fitted in a face plate provides the drive for the work.

Three and Four Jaw Chucks

The three-jaw universal chuck is used to hold round or hexagonal work The three-jaw universal chuck is used to hold round or hexagonal work. An internal scroll plate moves all three jaws at the same time. The four-jaw independent chuck can be adjusted independently by a chuck wrench. They can be used to hold round, square, hexagonal, and irregular shaped workpieces. The jaws can be reversed to hold work by the inside diameter.

Cutting Tool Holding Devices STRAIGHT TOOLHOLDER LEFT-HAND OFFSET RIGHT-HAND OFFSET KNURLING TOOL

Tool holders are held in a tool post Tool holders are held in a tool post. The rocker base must be adjusted so the point of the tool bit is placed on the centerline of the work. Quick change tool posts allow the changing of tools very easily. Speeding up the machining process.

Carbide inserts or brazed carbide tools allow cutting speeds to be increased up to four times as fast as traditional high speed tool bits.

A follower rest bolts to the carriage and moves along the work preventing it from springing up and away from the cutting tool. It is used to support long slender work. A steady rest is also used to support long slender workpieces while being machined between centers, or while being machined at one end while the other is held in the chuck. It bolts to the ways and does not travel with the tool.

Lathe Operations

If the tailstock is moved closer to the operator If the tailstock is moved closer to the operator. The tailstock end will be smaller than the headstock end. If this is intentional it would be called a taper. A taper is defined as an uniform increase or decrease in diameter of a work piece measured along its length. This can be computed using a mathematic formula.

Turning the TAPER Loosen the tailstock clamp to make the adjustment possible. Use the allen screws on each side of the tailstock base to move the center toward or away from the operator. Snug up the screws so they are not loose