LATHE PARTS-TAILSTOCK AND MAIN SPINDLE

 Lathe parts-Tailstock and Main spindle

. the parts of a tailstock

. uses of tailstock

. functioning of a tailstock

. functions of the main spindle

. features of main spindle

Tailstock

It is sliding unit on the bed ways of the lathe bed. It is situated on the right hand side of the lathe. It is made in two parts namely tha base and the body. The base bottom is machined accurately and has 'V' grooves corresponding to the bed-ways. It can slide over the bed and can be clamped at any position on the bed by means of the clamping unit. The body of the tailstock is assembled to the base. Gradutions are marked on the rear end of the base and a zero line is marked on the body.

When both zero lines coincide the Axis of the tailstock is in line with the axis of headstock.

The body and base are out of cast iron. The parts of a tailstock are

-base(a)

-body (b)

-spindle (c)

-spindle locking lever(d)

-operating screw rod(e)

-operating nut(f)

-tailstock hand wheel (g)

-key (h)

-clamping nut(i)

-adjusting screws (j)

Functioning of a tailstock

By rotating the hand wheel, the barrel can be moved forward or backward. The barrel can be locked in any required position. The hollow end of the barrel at the front is provided with the a morse taper to accommodate the cutting tools with a  taper shank. Graduations are sometimes marked on the barrel to indicate the movement of the barrel. With the help of the adjusting screws, the body can be moved over the base laterally, and the amount of movement may be read approximately refering to the gradutions marked. This arrangement is to offset the centre of the tailstock as required for taper turning.

Purpose of the tailstock

To accommodate the dead centre to support lengthy work to carry out lathe operations.

To hold cutting tools like drills, reamers, drill chucks provided with taper shank.

To turn external taper by offsetting the body of the tailstock tailstock

ect to the base.

MAIN SPINDLE

The main spindle is fitted on the headstock. It has facilities for holding and rotating the Work-holding devices, and, therefore, the work itself.

Features

The main spindle is hollow so as to accept the bar stock and also to reduce the weight. It is hardened, ground and super finished to high accuracy. In the assembled condition in the headstock, its Axis is perfectly parallel to the lathe bed-ways. The main spindle is carried and supported by anti -frictional ball, roller, thrust and taper roller bearing according to the design of the machine.

The portion of the main spindle, which is outside the headstock box section, is known as the spindle nose.

It is bored internally to a morse taper to accept the adapter sleeve which, in turn, accommodates the live centre. The periphery of the spindle nose has provisions for mounting the work-holding devices.

TYPES OF SPINDLE NOSES AND THEIR FEATURES

Plain threaded spindle nose

Long taper spindle nose

Short taper spindle nose

Spindle nose  mounting with tapered matching surfaces are preferred as they are self aligning, and compensate for normal wear without much loss  of accuracy.

The spindle located in bearing enables to have its axis and the axis of the work -holding device mounted upon it parallel to the bed slideways of  the machine both in the horizontal and vertical planes.

The main spindle, its bearing and the headstock casting are sufficiently rigid to prevent the mass of the work and the Work-holding device, together with the cutting forces, from deflecting the spindle axis from its