Technical Drawing Labeling: Standards and Tools
Definition of Labeling
Definition: Labeling is the art of writing letters and numbers according to established standards.
Background of Labeling
Background of the labeling: In the late nineteenth century, C.W. Reinhardt, former chief designer of the Engineering News, recognized the need for a simple and readable font using basic lines. This led to the development of upper and lowercase alphabets based on Gothic letters and a systematic series of strokes.
Standardization of Letters
Standardization of letters: After Reinhardt, a confusing variety of letter styles emerged. In 1935, the American Standards Association established standards for letters, known today as ASA rules.
Standardization
Standardization: Labels and dimensions in technical drawings must adhere to standards to avoid confusion.
Calligraphy DIN
Calligraphy DIN: Standard letters are governed by DIN, which stands for ‘Dat Ist Norm’ (this is normal). Calligraphy DIN refers to the work of the German standards commission and includes two types: DIN 16 and DIN 17.
Labeling Rules
Labeling rules:
- Width of the letter: determined by the labeler.
- Height of the letter: determined by the labeler.
- Separation between letters: one-fourth of the letter’s width.
- Separation between words: three times the separation between letters.
- Separation between lines: equal to the height of the letter.
Pens for Labeling
Pens for labeling: A medium-soft pencil with a tapered tip is suitable for labeling, typically from the H series, such as 4H or 6H.
Importance of Labeling
Importance of labeling: Labeling is crucial in technical drawing, clarifying aspects that the design alone cannot explain.
Drawing Table
MESA – PANEL: The drawing surface should be smooth, made of wood, sheet, plastic, or other material. The table should have adjustable inclination and proper lighting from right to left and front to back to avoid shadows. A straight working edge, checked with a steel rule, is essential.
T-Square
RULE: A T-square with a head must be held firmly against the board’s edge to ensure parallel lines. It also supports drawing angle brackets. For wooden T-squares, ensure the blade is perfectly straight.
Triangles
BRACKETS: Commonly used triangles are 60, 30, and 45 degrees. They are used with the T-square for drawing parallel, vertical, or inclined lines. Made of celluloid or transparent plastic, they are also called gussets.
Scales
ESCALIMETRO O SCALE: Scales, usually referring to the metric system, include 1:100, 1:75, 1:50, and 1:20. Accurate measurements are crucial, and the scale used must be indicated. Scalers are metric rules graduated in centimeters and millimeters, often with a pyramidal shape and two different scales.
Compass
THE MEASURE: This tool draws circles and arcs, with one arm having a tip and the other a nail or mine. The central screw provides rigidity to maintain the opening.
Drawing Pencils
PENCIL DRAWING: Special pencils with graded leads are used, with hardness indicated by numbers and letters. Hard pencils create lighter lines than soft pencils with equal pressure. It is a basic tool for representation.
Templates
TEMPLATES: Templates are used to draw standard shapes like squares, hexagons, triangles, and ellipses, saving time and improving accuracy.
Eraser Shields
INSOLES Del: Thin metal pieces with openings allow for erasing small details without affecting the rest of the drawing. Rubber pencil erasers are recommended.
Irregular Curves
IRREGULAR CURVES: These tools, based on combinations of ellipses and spirals, draw curved lines with non-constant radius. They are also called curve guns.
Pencil Sharpeners
SHARPENER: After cutting the wood, sharpen the graphite to a long, tapered tip.
Erasers
Eraser: Soft erasers, also called milk or Nysón, clean paper or canvas and remove dirt. Spray cleaners are also used for graphite residue.
Drawing Ink
DRAWING INK: Drawing ink is finely divided coal dust in suspension with natural or synthetic rubber to prevent it from flowing easily with water.
Tracing Materials
To trace CLOTH OR PAPER FABRIC: Finely woven cloth coated with starch or plastic is used for drawings with pencil or ink.