A Text Book on Engineering Graphics - Central Board of Secondary ...

Solution:
Example 3 :
Solution :
D = 0.866 P
(i) Draw vertical centre lines P/2 apart i.e. 50/2=25mm apart.
(ii) Draw horizontals to indicate D, D=0.866, apart.
MACHINE DRAWING
(iii) Cut off one eighth of D at the top and one sixth of D at the bottom or draw
horizontals to indicate d=0.61P with the 'D'.
(iv) Draw the slanting lines representing the sides of the thread. Here the angle
between the flanks is 60°.
(v) Make the crest flat and roots round. Roots are made round by any suitable method.
(vi) Hatching is done as shown in fig.2.6. This lower hatched profile shows the basic
form of the bolt.
(vii) Dimensioning is done as shown is FIG 2.6
D
8
d = 0.54 P
D
4
Draw to scale 1:1, the standard profile of metric screw thread (internal) taking
enlarged pitch as 50mm. Give standard dimensions.
Refer Fig 2.7
P
50
60º
P 0.5 P
D=0.86P
43
INTERNAL THREAD
d=0.54P
27
Fig 2.7
48 ENGINEERING GRAPHICS
D/8
6.3
D/4
12.5
METRIC SCREW THREAD PROFILE