Mechanical drawing is governed by drafting techniques with special considerations on the size, shape, and details of the picture or idea. A base understanding of the drafting tools and techniques is required in this method. All drawings should first be done very lightly in pencil and then inked after the drawing has been verified for correctness. There are different types of mechanical drawing:

Orthographic Projection
This is also called a working drawing as it shows the accurate detail and dimension of the object. In orthographic projection, the top, front, bottom, left, and right sides of an object are shown.

Pictorial Drawing
Pictorial drawings present an object in a manner similar to a photograph. These pictures are usually used in advertise and brochures. The most frequently prepared pictorial drawings are isometric, perspective, and oblique.

Perspective Drawing
A perspective is one of the most basic aspects of drawing. Perspective drawing looks three-dimensional or realistic. It is drawn to make objects appear to the eye in relation to its distance from the viewer. It means that objects that are farther from the eyes will appear smaller or if the object is long, it will appear to vanish at the end of the drawing.

Here are some simple rules to follow in making perspective drawing:

1.The person making the drawing remains in the same place all the time. his is called the station point.
2. The horizontal line is always at the eye level of observer on whatever direction she he looks-north, south, east, or west.
3. Vanishing point is the point at which the lines on the horizon converge.
4.The picture plane is an imaginary vertical surface between the artist and the subject.

Schematic Drawing
This style of drawing is sometimes referred to as network or systems drawing. It consists of diagrams where special symbols are used to describe the signs in electrical circuits, organizational chart, flow chart, production and transportation system, and many other processes.

Artists prepare schematic diagrams by using templates to trace the symbols on the drawing.
Drawing Materials Artists use various drawing materials.

1. Pencil- The graphite or lead pencil, with grades 6B (soft) to 9H (hard), gives various effects on lines. A hard pencil can be used to make detailed realistic d drawings while a soft pencil is suited for sketching.

2. Charcoal - Charcoal is excellent for rapid sketching. Charcoal gives a broad soft and sometimes bold line and a wide variety of tone.

3. Crayon and Chalk- Crayon is a general term for any drawing material in stick form. Professional artist rarely uses the inexpensive wax crayon which are popular with children.

4. Pen and Ink - In early times a reed or bird quill served as a pen. Pressure on the pen affects the Felt-tip and markers are excellent for work on a sketchbook.

5. Brush - Brush is used to draw both fine and silver point. The silver point medium is perhaps broad lines.

6. Silver Point - Silver point is a stylus with a most exacting form of drawing because when mistakes are committed, they cannot t be correct

Measurement in Drawing

Measurement is necessary in drawing. The English system (inches, feet, yard) or the Metric system of measurement may be used. The Metric system has units in multiples of 10 differentiated by the use of prefixes, such as milli-, centi-, and kilo. 

Here are some measuring instruments in drawing:

These are the most often used instruments in drawing. For beginners, rulers can be used. Scales are triangle in shape, their flat sides have gradations and numbers

Triangles come in different sizes of transparent materials. These are used for doing vertical lines and forming angles of different degrees in 15 variations.

This instrument is useful in drawing the horizontal and straight lines of a triangle. 

4. Compass
A compass is used to construct a circle.

5. Divider
A divider is similar to a compass except for its two metal parts. It is, likewise, used to transfer line and divide other lines into equal parts.

6. French Curve
This instrument is used to draw irregular curves

Lines Used in Mechanical Drawing

Object Lines

The object line (whether fine or heavy) describes the - shape of the object and is generally heavier than the other lines. It must be uniform in width and should not thin out near the ends.

Dashes or Hidden Lines

Hidden lines are short dashes about 4-inch long. They - indicate edges, surfaces, and shapes of parts that are visible or hidden by another object. Center Lines
The center lines are series of thin long and short lines that serve as centering and locating parts. They serve as a line from which measurements are taken.

Dimension and Extension Lines

These lines indicate the extent of a given dimension and they terminate in an arrowhead which touches the extension lines.

Section Lines

Section lines are drawn to show (shade) that portion which has been "cut" by a cutting plane. Lines are drawn at 45" or 60 using a triangle.

Cutting Plane Lines

These lines indicate where one view has been "cut" in order that a sectional view may be drawn to show the shape of the object in the plane of the cut.

Break Lines

The break lines indicate that a portion of an object has been omitted from a drawing.