OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 3
located accurately. If the centers are not located properly, the four individual
arcs will not meet to form a smooth, continuous ellipse. A good practice that will
help you draw a smooth, continuous ellipse is to lightly construct the ellipse,
then check it for accuracy before drawing in the final heavy arcs.
FOUR CENTER METHOD OF
DRAWING AN ISOMETRIC
An isometric hole template may be conveniently used as a guide for drawing the hole
size for which it is cut.
To align the template for drawing, first draw in the
hole center lines, then align the guidelines printed on the template adjacent to
the desired hole with the center lines on the drawing. If you are still unsure of
how to position the template, draw in the center lines and the major and minor axes
of the ellipse as shown in figure 44 (on the following page).
Then align the