1. Presentation on
Capstan, Turret Lathe 1

2. Introduction Turret Lathe(semi-auto)
The basic purpose of all these machines is to minimize human labour involved in the process and make it as much automated and refined as possible. Lathes which are used for metal cutting in industrial processes are normally required to produce products on a mass scale.
A single product requires several machining operations which in
turn would require several different kinds of tools to carry out these operations. If an operator were to manually adjust each tool after every single operation, this would certainly consume a lot of time and unnecessary efforts.
Keeping the above limitations in mind the engineers came up with
the idea of a typical lathe machine where everything could be fitted and configured in one go literally speaking. Such a metal working lathe which has got a turret and can perform several
functions in an automated fashion is known as a turret lathe.
National Institute of Technology Mizoram 2

3. Schematic configuration of turret
lathe
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4. Pictorial view of a turret lathe.
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National Institute of Technology Mizoram

5. Capstan lathe (semi-auto)
Capstan lathe is one of the types of semi-automatic lathe. In semi-automatic lathes machining operations are done automatically. Functions other than machining like loading and unloading of job, positioning of tools coolant operations are done manually.
A capstan lathe is a milling machine used to create the same parts over and over again. The cutting bits are mounted on a rotatable turret known as a capstan, which allows the user to quickly change the orientation of the bits for cutting without having to take off the first bit and then mount the second. A piece of raw material, sometimes known as a blank, is mounted into the capstan lathe and is then spun at high speed. The cutting tools, sometimes known as knives, are then used to cut into the blank to create a new shape or design

6. Capston lathe Schematic diagram
Pictorial view

7. Differences in between capstan and turret
lathes
Turret lathes are relatively more robust and heavy duty machines
,Capstan lathes generally deal with short or long rod type blanks held in collet
whereas turret lathes mostly work on chucking type jobs held in the quick acting chucks
In capstan lathe, the turret travels with limited stroke length within a saddle
type guide block, called auxiliary bed, which is clamped on the main bed as indicated in Fig. whereas in turret lathe, the heavy turret being mounted on the saddle which directly slides with larger stroke length on the main bed as indicated in Fig.
One additional guide rod or pilot bar is provided on the headstock of the turret lathes as shown in Fig. to ensure rigid axial travel of the turret head
External screw threads are cut in capstan lathe, if required, using a self
opening die being mounted in one face of the turret, whereas in turret lathes
external threads are generally cut, if required, by a single point or multipoint
chasing tool being mounted on the front slide and moved by a short lead sc7rew and a swing type half nut.

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8/27/2017