Page 185 - Engineering drawing from first principles using AutoCAD

178 Enqineerinq drawinq [rom first principles

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Figure 8.5

• Hatch to the minor diameter where no thread assembly takes place.
• The end of the stud may be finished with a chamfer or radius. The radius is equal in size to
the outside diameter of the thread and to the large radius on the face of the nut. Assume
that the length of the stud is the usable part which does not include the radiused portion.

Exercise 1: draw a sectional view of a stud assembly in a
tapped hole given the following dimensions

• M20 stud: length 65mm, threaded 35mm at one end and 17mm at the other;
• M20 tapped hole: thread depth 24mm;
• component 13mm thick;
• 1mm thick gasket;
• M20 nut and locknut;
• depth of tapping drill 28 mm.

Isometric view of nut

Figures 8.6-8.8 shows the stages in drawing an isometric view of a large nut which could
be found on an exploded view of an assembly. Car service manuals use exploded views.
For this example use the dimensions for an M30 nut in Table 8.1 and set out the drawing
at twice full size. For accuracy it is often more convenient to draw to a large scale and
adjust the print size according to requirements.
Stage 1 shows the construction lines. I often find it convenient when transferring
distances from one view to another to use circles, as this stage shows. After drawing
the first circle the computer remembers its radius, and this is accurate for repetition work;
they can easily be deleted later. The dimensions used are as follows: