Unit 2.Drawing applied to technology
Feb 24, 2016
Unit 2.Drawing applied to technology
What are we going to see in this unit? 2.1 Drawing tools and how to use them 2.2 Drafts and sketches 2.3 Drafting scale 2.4 Diedric system 2.5 Marking and standardizing
Unit 2.Drawing applied to technology
2.1 Drawing materials and instruments
Paper Paper is made of cellulose that is obtained from
trees The paper size that we use is A4 . It is the result
of dividing 1 m2 (A0) four times by half the longest side.
2.1 Drawing materials and instruments
Pencil A pencil is lead in a wooden casing. The
lead is made with graphite and clay
clay
Graphite
Lead
Wooden casing
2.1 Drawing materials and instruments
Pencil hardnessThe more clay it contains the harder the lead
will be. We use letter H for hard pencils and letter B for soft ones.
Hard: H Soft: B
Very hard Hard Medium Soft Very soft
6H 5H 4H 3H 2H H HB B 2B 3B 4B 5B 6B
less clayMore clay
Technical drawing
Artistic drawing
2.1 Drawing materials and instruments
Mechanical pencilsThey hold graphite lead. They can be used for
technical drawing if used with a soft lead.
ERASERSErasers are made of rubber; they absorb graphite and erase it.
2.2 DRAFT AND SKETCH
DRAFT: It is a free hand drawing (with just a pencil). We show an idea or object without totally defining it.
2.2 DRAFT AND SKETCH
ATTENTION! A DRAFT IS NOT A BAD
DRAWING AND A SKETCH IS NOT A GOOD DRAWING !!!!!!
2.2 DRAFT AND SKETCH
The sketch: It is a free hand drawing too, but it includes the measurements, therefore it shows the precise size and a shape similar to the final drawing.
measure
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2.2 DRAFT AND SKETCH
Activity: draw a sketch of your home cupboard.
2.2 DRAFT AND SKETCH
the Sketch
2.3 Drafting scale We define scale as the relationship
between the size of the drawing and the real object.
A model uses a reduction scale
2.4 Diedric system
2.4 Diedric systemThe diedric system represents the objects
using a perpendicular projection on a plane
2.4 Diedric systemThe projection or VIEW consists of drawing just
what we see when we are perpendicular to the object and to the plane
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2.4 Diedric systemTo define an object we only need 3 views, top, front and
profile: Top view: from the top of the object Front view: facing the object Profile view: from the side
Profile view
Top view
Front view
Front view
Top view
Profile view
2.4 Diedric systemDiedric RulesThe front is usually indicated with an arrowThe views distribution
The front is always on top of the top view The profile is situated the other way round,
that is, the left profile is situated on the right
front
top
Left profile Right profile
top
front
2.4 Diedric systemRemember: The same height: the object has the same height on the
floor and on the profile views The same width: on the front and on the top views The same depth: on the floor and on the profile views
2.4 Diedric systemExercise: Draw the front, left profile
and floor views of the class chair
2.4 Diedric system Exercise: Draw the front, profile and floor
views of the class chair
2.4 Diedric systemWhere do we have to be situated to see these objects like circles?
2.4 Diedric systemExercise 11: Complete the views of the following objects
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2.4 Diedric systemExercise 11: Complete the views of the following objects
2.4 Diedric systemExercise 11: Complete the views of the following objects
2.4 Diedric systemExercise 11: Complete the views of the following objects
2.4 Diedric system Non visible lines: when we know there is a hidden
line we have to draw it using a discontinuous line
hidden line
2.5 Marking and standardizingStandardizing is the group of rules
that defines technical drawing. For example:
For paper size we use the DIN rule: A0,A1,A2… The lines are:
Thick continuous lines: are used to outline objects Thick discontinuous lines: indicate hidden lines Thin continuous lines: are used for auxiliary measures
and reference lines
2.5 Marking and standardizing
Dimension line
Extension Line
Measure
Reference line
2.5 Marking and standardizingOutside thick
continuous line
a discontinuous line of medium thickness for a hidden edge
2.5 Marking and standardizing
Marking : indicating the real dimensions of the object
Vocabulary
Paper size Cellulose Clay, graphite, lead Hard and soft pencils Erasers, technical pencil Sixty and forty-five degree rules Sketch, draft, free hand drawing, measures Scale, real and drawn size, reduction, enlargement
scales To be reduced 100 times… Length, height, width Long, high, wide.