370 Machine Drawing
dharm
d:\N-Design\Des19-1.pm5
1. A-C-I-K 5. A-C-J-L
2. B-D-I-K 6. B-D-J-L
3. G-E-I-K 7. G-E-J-L
4. H-F-I-K 8. H-F-J-L
For providing drive to the feed gear box from the spindle, gear M of module 2 mm is rigidly
fixed to the spindle.
Figure 19.10(b) shows the isometric view of the headstock body and both the side views.
The details of the bearing cover plates are indicated in the side views.
19.3.4 Milling Machine Tail Stock
Certain jobs requiring milling operations, in relation to their axes of rotation, are usually supported
between centers. An assembly drawing of a milling machine tail-stock is shown in Fig. 19.11. The
job is held between the centre in the dividing head and adjustable center provided in the tail-
stock. This is similar to the lathe tail-stock.
To fix the work between centers, the dividing head spindle is first brought to a horizontal
position. Then, one end of the work is supported in the work center of the dividing head spindle,
with the help of a mill-dog. The tail-stock position is then adjusted to suit the length of the work
and it is then clamped to the table of the machine, in that position. After clamping of the tail-
stock, fine adjustment can be made by rotating the knurled hand wheel 3. The knurled hand
wheel is attached to the center by the screw 4, washer 6 and nut 7. This will allow tail-stock
center 2 to slide horizontally in its guide. After setting correctly, the center is clamped by means
of screw 5.
Unlike the lathe tail-stock, there is no relative motion between the center and the work
piece in the milling machine tail-stock; hence the center may be made of mild steel.
19.3.5 Lathe Travelling Rest
It is an attachment to a lathe machine for supporting long slender work pieces against the cutting
tool forces. Figure 19.12 shows an assembly drawing of a lathe travelling rest. The design permits
it to be clamped to the carriage of the lathe, enabling it to travel along with the cutting tool. The
two jaws 2 are positioned slightly behind the cutting tool, so that the bearing is taken on the
round portion of the job, which has been just finished. The two supporting jaws of the rest, resist
the cutting forces. Jaws may be adjusted by the hexagonal headed screws 3 and clamped in
position in the main body 1 by means of set-screws 4. A flat surface is provided on the jaws, for
effective clamping. A guide strip 5 is used for the proper adjustment of the travelling rest on the
guide ways of the carriage. To reduce the damage to the finished surface of the job, the jaws are
normally made of brass.
19.3.6 Self-centering Vice
Figure 19.13 shows the assembly drawing of a self-centering vice. This is used as a quick acting
fixture for locating and holding circular shafts and work pieces for cutting keyways, grooves,
slots, etc. The vice consists of a CI body 1 into which a V-block 4 may be fitted tightly. Based on
the size of the workpiece, the size of the V-block is chosen. Two CI jaws 2 are fitted to the body
with the help of pins and the pins provide swivelling action to the jaws, to clamp the workpiece
onto the V-block.
Two cylindrical nuts 7 and 8 are located on the other ends of the jaws. A right hand screw
5 engages the nut 7 and the screw has a collar at the other end. A left hand screw 6 is fitted in the
collar and engages the nut 8. The handle 9 is fixed to the other end of the screw 6 by means of the
taper pin.
