Difference between Capstan and Turret lathe

Introduction

Before understanding difference between capstan and turret lathe let us first understand what a lathe is and how it is different from the capstan and turret lathe.

Lathe is a machine used to done various operations such as drilling, boring, knurling, thread cutting, facing etc. on the workpiece to make it a value added product. In classical lathe machine such as in center lathe there is only one tool post and only one tool fitted in the tail stock, which usually takes time while changing tools for different operations.

There are certain difficulties that cannot be overcome by center lathes such as: the large time involvement while setting and movement of tool between the machining processes, unsuitable for mass production, less no of speeds, one tool fixation in the tailstock etc. thus the center lathe is modified to turret and capstan lathe to overcome all these difficulties.

Capstan and Turret lathes are the advancement of the Engine lathes and center lathe, wherein the tailstock is replaced by a hexagonal turret tool head, having 6 different tools in the turret, where turret tool is rotate in each operation according to process requirement. These are used to produce large number of identical parts in minimum time and are used for mass productions in less time with maximum accuracy and precision. These are the semiautomatic lathes which mean that all the machining process such as boring, drilling, thread cutting, facing, turning etc., without changing of tools, are to be done automatically and other functions like setting of tools, clamping of workpiece, cooling of process are to be done manually. These machines can be used to machine from small to large workpiece and are costlier than engine lathe because of having complex construction.

Although capstan and turret lathe appear same in first sight but they differ in many aspects such as sizes, operation, constructions etc. So let’s here go through the difference between them.

^Capstan Lathe

*Turret Lathe

^It is a Light weight machine.

*It is a heavy weight machine.

^In capstan lathe the turret tool head is mounted over the ram and that is mounted over the saddle.

*In turret lathe the turret tool head is mounted over the saddle like a single unit

^For providing feed to the tool, ram is moved.

*For providing feed to the tool, saddle is moved.

^Because of no saddle displacement, Movement of turret tool head over the longitudinal direction of bed is small along with the ram.

*Turret tool head move along with the saddle over the entire bed in the longitudinal direction.

^Used for shorter workpiece because of limited ram movement.

*Used for longer workpiece because of saddle movement along the bed.

^Its working operations are fast because of lighter in constructions.

*Its working operations are slower because of heavier in constructions.

^Heavy cuts on the workpiece cannot be given because of non-rigid construction.

*Heavy cuts on the workpiece can be given because of rigid construction of machine.

^For indexing turret tool head, the hand wheel of the ram is reversed and turret toll index automatically.

*For indexing turret tool head, turret is rotated manually after releasing clamping lever.

^The turret head cannot be moved in the lateral direction of the bed.

*The turret head can be moved crosswise i.e. in the lateral direction of bed in some turret lathe.

^In capstan lathe, Collet is used to grip the Job.

*In turret lathe, power Jaw chuck is used to grip the Job.

^Used for machining workpiece up to 60mm diameter.

*Used for machining workpiece up to 120mm diameter.

^These are usually horizontal lathes.

*Turret lathes are available in horizontal and vertical lathes.