TECHNICAL DRAWING

Unit 2.Drawing applied to technology

Unit 2.Drawing applied to technology

What are we going to see in this unit?2.1 Drawing tools and how to use them2.2 Drafts and sketches2.3 Drafting scale2.4 Diedric system2.5 Marking and standardizing

2.1 Drawing materials and instruments

PaperPaper 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 instrumentsPencil

A pencil has a lead covered with wood. The lead is made with graphite and clay

clay

Graphite

Lead

Wood cover

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 clay

More clay

Technique draw Artistic draw

2.1 Drawing materials and instruments

Mechanical pencilsThey hold a 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.

2.1 DRAWING TOOLS

THE RULER

It is a precision tool that makes it possible to measure and to transfer a distance.

TRIANGULAR SET SQUARE

A set square is a tool for drawing perpendicular (vertical) and parallel lines and for obtaining angles.

There are 2 types of trianglular set squares

A 45 degree

A 60 degree

2.1 Drawing materials and instruments

How to draw vertical and parallel lines with the set square

Vertical: Parallel:

Activity: Draw the set squares in your notebook as you can see them in

both positions

2.1 Drawing materials and instruments

Activity :Draw a chessboard using the set square. The separation between

squares is 2 cm!

square16 cm

16 cm

2.1 Drawing materials and instrumentsDrawing angles: we can get 15º, 30º, 45º,

60º, 75º, 90º, 120º, 135º…angles combining the 30º, 45º , 60º and the 90º angles from the set

squares

You don't have to copy them because you can find them in your text book on page 25

2.1 Drawing materials and instruments

Drawing angles exercise: you have to obtain, 45º, 75º, 90º, 120º

angles combining the set squares

2.1 Drawing materials and instruments

Drawing angles exercise: you have to obtain, 45º, 75º, 90º, 120º angles combining the

set squares

2.1 Drawing materials and instrumentsThe CompassIt is used for drawing circles and angles

Advice: sharpen the lead tip by rubbing it on a fingernail file