A Text Book on Engineering Graphics - Central Board of Secondary ...
A Text Book on Engineering Graphics - Central Board of Secondary ...
A Text Book on Engineering Graphics - Central Board of Secondary ...
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MACHINE DRAWING<br />
Steps involved are similar to the previous example. Here the upper hatched pr<strong>of</strong>ile shows the<br />
basic form <strong>of</strong> nut.<br />
2.4.3 SQUARE THREAD<br />
Mechanisms <strong>of</strong> machine tools, valves, spindles, vice screws etc. are generally provided with<br />
square threads. A "square thread (SQ) is specified by nominal diameter and pitch". For example a<br />
square thread <strong>of</strong> nominal diameter = 40 mm and pitch = 4mm is designated as SQ 40x4<br />
Let us now learn to draw the standard pr<strong>of</strong>ile <strong>of</strong> a square thread, taking enlarged pitch as 60mm.<br />
Soluti<strong>on</strong> :<br />
Steps Involved<br />
Refer Fig 2.8<br />
(i) Draw two horiz<strong>on</strong>tals, P/2 apart i.e. 60/2= 30mm apart.<br />
(ii) Draw a number <strong>of</strong> perpendiculars, 30mm apart so as to have a row <strong>of</strong> squares.<br />
(iii) Hatching and dimensi<strong>on</strong>ing is d<strong>on</strong>e as shown in fig 2.8<br />
0.5P<br />
2.4.4 KNUCKLE THREAD<br />
P 0.5P<br />
Fig 2.8<br />
Knuckle thread is a modified form <strong>of</strong> square thread. Knuckle thread is a special purpose thread. It<br />
is used in railway carriage coupling screws and <strong>on</strong> the neck <strong>of</strong> glass bottles.<br />
Let us now draw the standard pr<strong>of</strong>ile <strong>of</strong> Knuckle thread.<br />
P<br />
60<br />
90º<br />
0.5P<br />
30<br />
ANGLE<br />
ENGINEERING GRAPHICS 49<br />
90°<br />
PROFILE OF SQUARE SCREW THREAD
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