Page 171 - Engineering drawing from first principles using AutoCAD

164 Engineering drawing [rom first principles

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Figure 7.13

the construction lines. Draw a horizontal line tangential to the top of the jug and extend
the two tapered sides in both directions to give the points 1, 13, and 0 (Fig. 7.14). Draw
the semicircle. Use the length Bl and the ARRAY command to give the radial lines 1 to
13. Remember to insert 14 for the number of lines in the polar array.
The method I adopt for spacing the numbers 1 to 14 equally around the circumference is
to draw a second circle parallel to the first, acting as a centre line, then use the TEXT
command to place the numbers in position. Any final adjustment necessary can easily be
made with the MOVE feature. Alternatively, if the numbers are needed several times, I
make a list in a convenient space away from the drawing and then reposition them with
the COpy feature. Erase the construction circle later when you are satisfied with the
result.
Draw the vertical lines from points 2 to 12 to the base of the cone as in the previous
example. Add the radial lines to intersect with point o. You will find that not all of the
vertical lines touch the line 1 to 13 in 'snap' positions. For each line commence at point 0
with SNAP engaged and draw the line passing through the required intersections to a
'snap' point above, then use the TRIM command to tidy up the linework. Alternatively,
for every line turn the SNAP feature off to position the lines accurately on the