- A standard is a level of quality or achievement
- Standards and rules that all drawings must follow.
- Set of rules of technical drawing like: Projection system, the types of lines, scales.
- International Organization for Standardization (ISO)
- Deutsches Institut für Normung (DIN)
- Una Norma Espaņola (UNE)
- American National Standards Institute (ANSI)
origin of pencil
- Pencil are made of a wooden case and lead inside made of graphite and clay
- Pencil grades:
- H for hard, thin lines and technical drawing.
- B for soft, thick lines and artistic drawing.
- From the hardest (9H) to the softer (9B)
- U.S. numbering system: 1(B), 2 (HB), 3(H), 4(2H).
origin of paper
- The weight of paper (Grammage) as grammes per square metre (g/m2 or gsm)
- 80gsm is the most commonly found weight.
- Types of paper sizes (formats):
- ISO A series used by almost every country.
- The ISO A series paper sizes are 4A0, 2A0, A0, A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10.
- A0 with an area of 1 m2.
- Aspect ratio Height= √2 * width.
- A4 is the most popular(the most frequently used paper size).
- Size of a A4 format: 210 x 297 mm.
- A1 is half the size of the previous format A0.
- The area of B series sheets is the geometric mean of successive A series sheets.
- The area of C series sheets is the geometric mean of the A and B series sheets of the same number.
- Examples of long formats: 1/3 A4, 1/4 A4, 1/8 A4, A4x3, A4x4, A4x5.
- American ANSI A (Letter), B, C, D, E.
Dimensioning Rules: ISO 129-1:2004 == UNE 1039:1994
- Elements of dimensioning should be drawn with finer(thinner) lines than the edges of the object (thicker)
- It is not necessary to dimension all the edges of an object (the minimum number of dimensions required to understand the drawing).
Elements of dimensioning:
- It is the number that show the real measurement of the object.
- Normally in millimetres.
- Must be in the centre (middle) of, and parallel to the dimension line.
- Must be above horizontal dimension lines and left of vertical dimension lines.
- If there is not space on the dimension line to put the dimensions, they can be placed on a leader line.
- Must be parallel to and the same length as the edge (side) of the object.
- Must be placed outside of the object.
- If there is a smaller object inside the main one you can put dimension lines inside the object.
- We cannot use the edges of the object as dimension lines.
- Dimension lines should not cross other lines.
- Dimension lines should be situated at least 8 mm away from the edge of the object.
- The following dimension lines should be situated at least 5 mm away from other.
Symbols at the end of the dimension lines:
- They are usually arrowheads or oblique stroke (slashes) or if there is not space to put arrowhead dots.
- If the arrows or dimensions do not fit on the dimensiones line, they should go outside the line.
- It is a line perpendicular to the dimension line.
- Extend for 2mm on each side of the dimension lines.
- This shows a note, a number, data related to the object.
- Before the dimension number.
- Radius: R Diameter: ∅ Square: □ Sphere: radio SR diameter S∅
- Angles are dimensioned with arcs.
- Radii and diameters can be dimensioned inside a circle or indicated by an arrow at the point of contact with the circumference.