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 m 2 (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 hardness The 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 hardHardMediumSoftVery soft 6H5H4H3H2HHHBB2B3B4B5B6B less clay More clay Technical drawingArtistic drawing

2.1 Drawing materials and instruments Mechanical pencils They hold graphite lead. They can be used for technical drawing if used with a soft lead. ERASERS Erasers 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 Page 41

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

The diedric system represents the objects using a perpendicular projection on a plane

2.4 Diedric system The projection or VIEW consists of drawing just what we see when we are perpendicular to the object and to the plane Page 28

2.4 Diedric system To 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 Top view Profile view

2.4 Diedric system Diedric Rules The front is usually indicated with an arrow The 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 system Remember: 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 system Exercise: 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 system Where do we have to be situated to see these objects like circles?

2.4 Diedric system Exercise 11: Complete the views of the following objects Page 31

2.4 Diedric system Exercise 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 standardizing Standardizing 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 standardizing Outside 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.