Technical Drafting Q1

Orthographic Projection

- The exact representation of a figure
- Process of representing 3d objects in 2d

Multiview Projection, Parallel Projection

Other terms of Orthographic Projection

Ortho-

Means straight, upright, vertical
(Came from Greek word 'orthos' meaning straight, right, true)

Graphic

marked by clear lifelike or vividly realistic description.

Glass Box

unfolding and transferring the height, width, and depth

3 Principal Views

Front View
Top View
Right Side View

3 Principal Planes

Frontal Plane
Horizontal Plane
Profile Plane

Working Drawing

used as a reference or guide in the manufacture of a product.

Assembly Drawing

[a part of working drawing dealing with] drawing various parts of a machine or structure assembled in their relative working positions.

Alphabet of Lines

a list of line symbols that engineers and draftsmen use in technical drawings to communicate specific shapes, sizes or surfaces.

Construction Lines

- used to construct layout work (guidelines)
- thin and very light, should not be erased

Visible Lines

- show outline of object, visible edges and surfaces.
- thick and heavy

Section Lines

- medium lines drawn at 45 degrees
- show interior view of solid areas of cutting plane line.

Hidden Lines

- short dash lines
- show non visible surfaces.

Center Lines

- long and short dash lines
- usually indicates center of holes, circles and arcs
- thin and dark

Dimension Lines

- show the size of an object with a numeric value usually located in the middle of the line
- usually with arrowheads or tick markings.
- thin and dark

Extension Lines

- show the starting and ending of dimension.
- thin and dark

Leader Lines

-medium line with arrowhead
- show label for size (e.g., radii) or special information about a feature.

Cutting Plane Lines

- extra thick lines
- show cutaway views or plane of projection where a section view is taken
- arrow indicates the direction of view.

Short Break Lines
Long Break Lines

- short and long medium line use to show cutaway view of a long section.
- SBL are used when the hidden part is rather short, while LBL are used when it's longer

Dimensioning

The process of adding size to a drawing information

Aligned Dimensioning
Unidirectional Dimensioning

Two systems of Dimensioning

Aligned Dimensioning

- numbers are aligned with the side of the feature being measured
- if dimension lines are drawn vertically on the right side of a drawing, the numerals would be flipped on its right
- dimension is written in two directions

Unidirectional Dimensioning

- reads from the bottom of the sheet and writes all numbers horizontally
- dimension is written in the same direction in the whole drawing

Arc

curved line that is a part of a circle

Fillet

- rounded sides of a polygon's vertices
-ex. tables with rounded corners

Chamfer

- the sloped or angled edges or corners of a part design
- straight and sharp angle, opposite of fillet