DRAFTING

By: IST

FOUR COMMON TERMS

• Drawing
• International language
• Freehand drawing/sketching
• Paper and pencil
• Mechanical drawing
• With instruments such as T-sqaure, triangles
• Orthographic projection
• Exact shapes and observation

METHODS OF DRAWING LINES

1. Orthographic
• Also called as 3 VIEW DRAWING
• Planes of porjection
• Frontal Plane Front View
• Horizontal Plane Side View
• Profile Plane Top View
• Glassbox technique
• Extracting or extraction of TV, SV and FV

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2. Pictorial
1. Isometric
• 3 Dimensional, 30 degrees, 30 x 60 degrees, triangle
2. Perspective
• Most realistic, visual observation
• Bird’s Eye View (becomes narrower)
• Man’s Eye View (horizontal plane)
• Worm’s Eye View (becomes bigger)
3. Oblique
• One side is parallel to another, 45 degrees
• Cavalier – actual measurement
• Cabinet – depth reduce to ½
• General – depth reduce to ¼

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TWO KIND OF DIMENSION

• Location Dimension – parts, size, shapes
• Detailed Dimension
• Overall – width, length, height
• Semi-detailed – minor measurements

• H – Hardness
• B – Softness

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Grades of Pencil

• Soft – 2B, 3B, 4B, 5B, 6B (softest)
• Medium – 3H, 2H, H, F, HB, B
• Hard – 4H, 5H, 6H, 7H, 8H, 9H (hardest)

Note: for lettering, find the choices where HB is included (ex. A. HB, B or 2H 4H

Grades of Pencil used for General Drafting

• HB – for lettering
• 2H – for line work
• 4H – for general

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Minimum requirement for drafting students

• 4H – for repenciling F or H – for all lettering and freehand work
• 6H – for light construction lines
• 2H – for visible object lines

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GEOMETRIC FIGURES

1. LINE
• Set of points
• Types of Lines
• Straight line – shortest distance between two points
• Parallel line – will never meet
• Perpendicular line – intersecting lines

2. Kinds of Angles
1. The simplest way to sort triangles is by their angle size:
• Acute triangle is one in which all the angles are acute (less than 90°).
• Obtuse triangle is one in which one of the angles is obtuse (more than 90°).
• Right triangle is one in which one of the angles is a right angle (exactly 90°).

• Another way to group triangles is by looking at the lengths of their sides:
• Equilateral triangle is one in which all three sides have the same length.
• Isoceles triangle is one in which two sides have the same length.
• Scalene triangle is one in which all three sides have different lengths

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3. POLYGONS

To convert inches to meters, follow the conversion table below.

• PROPORTION OF LETTERS
1. Normal letters – used when space is adequate
2. Extended letters – used when space is wider
3. Compressed letters – used when space is limited
4. Lightface – with very thin stems
5. Boldface – having heavy stems

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Guidelines

Roman�(thick and thin lines)

Gothic �(uniform width)

Italic Letters�(slant)

Script Letters�(cursive)

Text Letters�(fancy style of letters)

TYPE OF LINES

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• Break line (long – wavy, and short – pointy)

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• Cutting plane line

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Cutting plane line

• Visible line

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• Hidden line

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

• Center line

________ __ ________ __ ________

• Extension line

__________ __________ 

• Dimension line

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Fine line Figure Arrowhead

• Types of Section
1. Full section – cuts entirely across
2. Half section – symmetrical
3. Broken-out section – partial used when need exposure
4. Revolved section – show true shape
5. Removed or Detailed section – same as revolved but not shown on view
6. Phantom section or Hidden section – emphasized interior