PRIN. OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 2
the leadholder vertical and constantly against the inside edge of the hole pattern.
Check the finished circle with a scale.
g. Other Tools.
There are many tools, other than the ones already presented,
which are used to help create technical drawings. One such tool is an adjustable
curve or snake, which is useful when drawing unusually shaped curves.
Another tool is the drafting machine.
A drafting machine is a combination
T-square, triangle, protractor, and scale which, when used properly, will greatly
increase drawing efficiency.
The information previously presented for using a
T-square, triangle, protractor, and scale may be directly applied to using a
This concludes the discussion on drafting tools. In the following paragraphs, we
will discuss the fundamentals of geometric construction.
3.
Geometric Construction
Geometric constructions are the building blocks of drafting.
Every drawing,
regardless of its difficulty, is a geometric shape. A rectangle is four straight
lines and four right angles. A cam is a series of interconnected arcs of various
radii. Every repair shop technician must have a fundamental knowledge of geometric
constructions if he is to progress to more difficult work.
In the following paragraphs, we will discuss some of the geometric constructions
that may be encountered.
a. Points and Lines. A point, to a draftsman, is defined as the intersection of
two construction lines (figure 20 on the following page).
NOTE
A dot should not be used to define a point because a dot
may be easily confused with other marks on the drawing and
thereby cause errors.
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