Machine Drawing

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370 Machine Drawing


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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.

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