This document discusses common terms and methods used in technical drawing and drafting. It covers orthographic projection, pictorial drawing methods like isometric and perspective views, and types of lines and dimensions. Geometric shapes like triangles and polygons are also explained. Guidelines for lettering styles and types of technical drawing lines are provided.
2. 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
3. METHODS OF DRAWING LINES
A. 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
4. B. Pictorial
1. Isometric
3 Dimensional, 30 degrees, 30 x 60 degrees, triangle
2. Perspective
Most realistic, visual observation
o Bird’s Eye View (becomes narrower)
o Man’s Eye View (horizontal plane)
o Worm’s Eye View (becomes bigger)
3. Oblique
One side is parallel to another, 45 degrees
o Cavalier – actual measurement
o Cabinet – depth reduce to ½
o General – depth reduce to ¼
5. OVERALL
SEMI-
DETAILED
TWO KIND OF DIMENSION
• Location Dimension – parts, size, shapes
• Detailed Dimension
Overall – width, length, height
Semi-detailed – minor measurements
8. 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
9. 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
10. 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
11. 2. Kinds of Angles
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°).
12. 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
14. To convert inches to meters, follow the
conversion table below.
1 inch 0.025 meter
2 inches 0.050 meter
3 inches 0.075 meter
4 inches 0.10 meter
15. 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
22. TYPE OF LINES
Break line (long – wavy, and short – pointy)
Cutting plane line
Cutting plane line
23. Visible line
Hidden line
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Center line
________ __ ________ __ ________
Extension line
__________ __________
Dimension line
Fine line Figure Arrowhead
2.00
24. 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