decipher...

In our drafting subject, one of the topics that we have taken is the "Geometric construction". This geometric construction is basically an important thing for engineering aids, as a draftsman. A draftsman must possess the knowledge of the principles of geometric construction and also its application. This often involves drawing lines, a circle, an arc of a circle or a fillet, a circular curve, or a combination of these basic types of line.

Here is an example of a basic steps in geometric construction.

The following are needed:

Bisecting a Line
Steps:

Start with a line segment PQ.


Place the compass on one end of the line segment.


Set the compass width to a approximately two thirds the line length. The actual width does not matter.


Without changing the compass width, draw an arc on each side of the line.


Again without changing the compass width, place the compass point on the the other end of the line. Draw an arc on each side of the line so that the arcs cross the first two.


Using a straightedge, draw a line between the points where the arcs intersect.


Done. This line is perpendicular to the first line and bisects it (cuts it at the exact midpoint of the line).




This is how to bisect a line. It's one of the basics done in drafting, and there are still many kinds of construction in drafting, there are also bisecting an angle, getting the center of a circle, equilateral triangle etc. All these things are very useful and it's important to learn all about these things.