A.SKETCHING AND TECHNICAL DRAWING

1. Technical SketchA sketch is an early drawing to express certain ideas into a design. It includes

some aspects of early design that need to be processed further. A sketch is the early communication medium for both the designer and user.

Drawing a sketch basically is by drawing a line with free hand, without using a ruler. Thus, the quality of the line shall be considered based on the character and type of picture to be presented. The quality of the line made by pencil is determined by the darkness (thickness) of the line and its width.

In a sketch, all lines have to start and end firmly and have logical relations with other lines from the beginning until the end. If two lines form an angle or intersection, both ends exactly have to meet.

Some steps to draw a vertical or horizontal line in a sketch are:a) Mark the start and end points.b) Make some moves between both points to adjust the eyes and hands with

the lines to be made.c) Draw a very thin line starting from the start to the end point. Direct the

eyes to the end point.d) Draw a line by darkening the thin line. Direct the eyes to the end of the

thin line.e) If a bowline that meets a straight line is going to be drawn, start from the

end of the bowline to avoid an inaccurate intersection.Some steps to draw a sketch of a picture are:a) Make the outline of the picture that consists of thin vertical, horizontal,

and bowlines.b) Draw the secondary lines, such as drawing the thin frame of a box/cube.c) Thicken the correct lines sketched. The thickness is adjusted to the

character of the lines drawn.When drawing a technical sketch, you will learn to draw isometrically. Usually an isometrical drawing is seen on an inclined plane, so that the visible planes are the upper, front, and side planes, or that are usually called the upper, front, and side view. Some basic principles of drawing an isometric projection sketch (inclined projection sketch) are:

a) All vertical lines look vertical.b) All horizontal lines look horizontal.

30O

30O

Figure 1.17 A 30O angle toward horizon

Figure 1.18 Isometric

c) All lines paralleled with the axis X, Y, Z can be drawn based on certain scale or proportion.

d) In an isometric projection, all the three visible planes get the same portion.

e) In an inclined projection, there is a vertical plane that is parallel with the surface of the drawing plane and looks as if it is real.

To be able to draw something isometrically, there are some rules:a) A vertical line is always vertical.b) All oblique lines heading downwards form a 30 degrees angle to the

horizon.c) All lines are drawn based on the actual size or on the same scale.d) The invisible side is drawn with dotted lines, whereas the visible side is

with thick lines.e) The thickness of the lines is twice of the dotted lines.f) The invisible sides can also be drawn with thin lines about a quarter of the

thickness of the thick lines.Below is an example of isometric view (inclined projection).

TASK 6

Figure 1.19 Stationery

2. Technical DrawingMany drawing tools are used when learning basic technology. By

drawing, concepts are easier to understand than by explanation only. The drawing is called technical drawing. In it a measure as the guideline of the size of the thing to be drawn is shown.

The term technical drawing literally consists of two words: 1. Drawing, which means a visual communication medium, and 2. Technique/method, which means a systematic work. Thus, a technical drawing is a method of visual communication to inform the design of a product. It has to meet the criteria: COMMUNICATIVE (easy to understand), NORMATIVE (based on rules), ACCURATE (technically precise), MEASUREABLE (using scale), and EFFECTIVE. a) Drawing Tools

The quality of a drawing depends on the hand of the maker and some factors such as: 1) Drawing Media: the kinds of drawing paper (HVS paper, manila

paper, padalarang paper, baking paper, tracing paper)2) Manual drawing tools: pencil, drawing

pen3) Digital drawing tools: a computer with

Computer Aided Design (CAD) program

4) Drawing instruments: drawing table,

Technical Sketch

1. Draw a sketch of a box that is 10 cm long, 5 cm wide, and 4 cm high by applying the 300 inclination principle as shown in the above figure.

2. Draw a sketch of a box that is 5 cm long, 4 cm wide, and 10 cm high by applying the 300 inclination principle as shown in the above figure.

3. Draw a sketch of a cube whose sides are 6 cm by applying the 300

inclination principle as shown in the above figure.

drawing machine, ruler, compass, protractor, screen printing, and eraser.

b) Drawing PaperA drawing paper is used for technical drawing whose size has been

standardized. The most common size used is the A series. This size has a standard label with a zero following the letter A (A0).

All sizes of paper are proportional so that it is easy to reduce or enlarge the size of a drawing. The sheet is easy to fold that is beneficial for filing documents. Smaller size of paper is relatively easier to fold and save either in or out of the office. Try folding the paper as small as possible to ease its filing and checking.

To obtain a smaller size paper you can divide an A0 sheet of paper into several smaller A size, as shown in the figure below.

A2

A1 A4 A3

A5 A5

Figure 1.20 Paper size

Table 1.2 Standard Size of Drawing Paper

No Series

Size

1 A0 841 mm x 1189 mm

2 A1 594 mm x 841 mm

3 A2 420 mm x 594 mm

4 A3 297 mm x 420 mm

5 A4 210 mm x 297 mm

4H . 3H. 2H. H. HB. 2B. 3B. 4B. 5B. 6B

HARDER SOFTER

Figure 1.22 Pencil Quality

Figure1.21 Mechanical Pencil

c) Drawing PencilWhen you draw something, you can

not mistakenly use a pencil. If the pencil used is too soft, the lines produced are too thick and dark and the drawing is not a good one. It is recommended that the pencil you used is not the soft one, not easily

broken, and can produce thin lines. The tip of the pencil shall be sharp enough. Thus, it is recommended to use a H, 2H, or 2B pencil. The table below shows the quality of pencils represented by letters and numbers.

d) EraserThe eraser used should be soft and clean.

e) RulerTo obtain an accurate measure, the stripes of a ruler must be put on the

items to be measured.

f) Drawing Table

Figure 1.23 A Plastic Ruler

Figure 1.24 A Drawing Table

Figure 1.25 A Pair of Triangular Ruler

A drawing paper is clipped on a drawing board using the clip attached to the board. On the left and bottom of the board there is an item that is used to move the ruler without making it attached closely to the drawing paper and without changing the position of the paper.

g) Triangular rulerA triangular ruler is used to draw vertical lines, lines with 30, 45, and 60

degrees angles, and to draw shaded-in area.

h) LineThe basic symbol of all drawings is a line. It determines the borders of a room, forms a volume, produces a structure, and connects a letter or a number. The lines in a paperwork and the intersections have to be sharp and solid, with the same width and value. There are five basic lines: dots, short line, long line, very long line, and continuous line.

Kinds of lines:

1) Bold Line : , also called drawing line.

It is used to draw something visible. It is the edge line or the border of a drawing.

2) Thin Line : (1/4 of the thickness of drawing line)

It is used as a helper or as a line to measure. 3) Short Dotted Line

It is used to draw the part that is to be unused, erased, or widened. 4) Axis Line: (1/3 of the thickness of drawing line)

It is used as an axis line, to show the sections and borders of the drawing when some parts are erased.

5) Dotted LineIt is used to draw the parts that are invisible because they are at the back.

i) Right-angled Projection Something drawn in a 30 degrees angle seen inclined so that three

sides are visible is called isometric projection drawing. If it is seen straightly, it is called right-angled or American projection in which only some parts of the plane that are visible.

In a right-angled projection, there are six viewing directions:1) Upper View is the view of a thing drawn seen from above.2) Bottom View is the view of a thing drawn seen from the bottom.3) Right View is the view of a thing drawn seen from the right side.4) Left View is the view of a thing drawn seen from the left side. 5) Rear View is the view of a thing drawn seen at the back.6) Front View is the view of a thing drawn seen at the front.

However, in American right-angled projection, something can be seen clearly if it is seen from 3 viewing directions, i.e. front, upper, and right view.

Upper View

Front View Right View

Figure 1.26 Isometric Picture and Right-angled Projection

TASK 7

Tugas 1Mengakatifkan komputer

SKETCHING AND TECHNICAL DRAWINGWork in your exercise book/milimeter block.To answer questions 1 to 4, draw four boxes having the same size as the following figure. Color them as instructed.

1. Closed Figure. Apply a different color for each of the visible sides.

2. Closed Figure. Apply a different color for each of the invisible sides.

3. Above the isometric projection, draw a small box whose upper side is open. Apply a different color for each of the visible sides.

4. Above the isometric projection, draw a small box whose upper side is open. Apply a different color for each of the invisible sides.