TECHNICAL DRAWING Designing things on paper TYPES OF DRAWINGS All - - PowerPoint PPT Presentation

TECHNICAL DRAWING

Designing things on paper

TYPES OF DRAWINGS

Artistic Sketches

(conceptual)

Diagrams

(design & technical)

Drawings

(technical/engineering)

Diagram

(design plan)

All Drawings Technical Diagram

(technical)

simulated

perspective Oblique

projection

Isometric

projection

Multi view

• rthographic

Less technical More technical

CONCEPTUAL SKETCHES

When

hen you f

• u fir

irst st get get an an idea f idea for

• r

somet something hing you

• u

want ant to to build build you

• u

may may dr draw aw it it rough

• ughly,

, without without using using instr instrument uments s

• r
• r accu

accurate te sca scales. les. This his is is called called a a conc concept eptual ual sk sketc etch.

 A conceptual sketch…

 Al

Allows s an i an idea dea to to be be exp xpresse essed d qu quickl kly y in n graphic phic for

• rm

 Is pr

Is prepa epared ed fr free ee-hand hand (w (withou thout d t drawi awing ng instr nstrume uments) nts)

 Is not done

Is not done to s to scale, cale, but i but it t respec espects ts the the rules of ules of te technical hnical dr drawi awing ng a as s muc much h as as possi possible, ble, a and i nd is made s made roug

• ughl

hly y pr propo

• porti

tiona

• nal to

to the object the object repr epresente esented. d.

CONCEPTUAL SKETCHES

On

On a sep separ arate te she sheet et of

• f pa

paper per dr draw aw a conceptual conceptual sk sketc etch h a a de devi vice ce used used to to cut cut a piec a piece e of

• f pa

pape per: :

CONCEPTUAL SKETCHES

On

On a sep separ arate te she sheet et of

• f pa

paper per dr draw aw a conceptual conceptual sk sketc etch h a a de devi vice ce used used to to cut cut a piec a piece e of

• f pa

pape per: :

TECHNICAL DRAWINGS

 Ser

Serve e as as a a ref efer erence to ence to wor

• rker

ers, s, ar architects hitects

• r
• r mac

machinists. hinists.

 When

hen you

• u ar

are r e read eady y to to des design ign the the details, details, you

• u mak

make e a a tec technical hnical dr drawing, awing, don done e with with mor more e detail detail and and mor more e acc accur urac acy.

CONCEPTUAL SKETCHES

On

On a sep separ arate te she sheet et of

• f pa

paper per dr draw aw a conceptual conceptual sk sketc etch h a a de devi vice ce used used to to cut cut a piec a piece e of

• f pa

pape per: :

CONCEPTUAL SKETCHES

On

On a sep separ arate te she sheet et of

• f pa

paper per dr draw aw a conceptual conceptual sk sketc etch h a a de devi vice ce used used to to cut cut a piec a piece e of

• f pa

pape per: :

DIFFERENCE:

Sk

Sketc etch: h: Made without drafting tools... Just pencil and paper. Scale is approximate, not accurate, but the sketch should still look like the object.

Dr

Drawing awing: Made with drafting tools... Ruler, set squares, protractor and

• compass. Scale should be accurate

and the drawing carefully made.

• Presents all the information necessary for the object’s

construction.

• Is made with great precision,
• Requires the use of rulers, compass and protractor or

drafting software.

• Is done to scale, and respects the proportions of the
• bject represented.
• Respects conventions in the mode of the representation.

A TECHNICAL DRAWING

TECHNICAL DRAWING OF FIGHTER PLANE

(ISOMETRIC PROJECTION, EXPLODED VIEW)

TECHNICAL DRAWINGS CAN REPRESENT THINGS…

TECHNICAL DRAWING OF A “SIMPLE” SPOON MU MULTI TI-VIEW VIEW, , OR ORTHOGRAPHIC THOGRAPHIC PR PROJECTI OJECTION ON

Photograph of Mercury Spacecraft

Technical Drawing of Mercury Spacecraft, Top View, Orthographic

 Technical Drawing of Mercury Spacecraft, Isometric Projection

TECHNICAL DRAWINGS CAN REPRESENT THINGS…

TECHNICAL DRAWINGS OF A “COMPLEX” SPACECRAFT

BAS ASIC IC TE TECHNICA CHNICAL L DR DRAWING WING LINES LINES

Visible

(Object) Line

Represents the

• utline

Thick

Draw the visible

• bject edges

with these lines

Hidden Line Shows hidden details Medium dashed

Draw hidden edges with these

Construction Line Used during drafting Fine

Faint lines, sometimes coloured

Dimension Line Used to indicate a dimension Fine,

with arrows 8cm

Dimension & extension lines go together!

Extension Line Used with a dimension line Fine

Near arrows

Center (Axial) Line Shows center or symmetry Fine

With dash in middle

8 cm

BAS ASIC IC TE TECHNICA CHNICAL L DR DRAWING WING LINES LINES

Ghost Line Shows possible movement Fine

dashed

Sometimes in

• ther color

Cutting plane line Position of a cross-section Thick

With arrows

Used only if you plan to draw a cross section

Hatched Lines Surface of a cross-section Fine

Show where it is solid (section view only!!)

Long Break Shows that a line is shortened Fine

With zig-zag

Used only for large objects

Short break (cutaway)

Object shortened

• r cut away

Medium

With curve

Leader Line Points to something Fine

With bent arrow

Attaches a comment

• r angle or dimension

to an object.

BASIC ASIC DRA DRAFTING FTING TOO OOLS LS

COMPARISON OF PROJECTIONS Projection Used for

Orthographic

(top view)

Drafting, maps, floor plans Orthographic

(multi-view)

Technical drawings, drafting, conceptual sketches (sometimes) True Perspective

(one, two or three point)

Artistic drawing, conceptual sketches Isometric

(simulated perspective)

Conceptual sketches, technical drawings (sometimes) Oblique

(simulated perspective)

Conceptual sketches

PROJECTIONS

Per

erspectiv spective e pr projections

• jections

Multi

Multi-view view pr projections

• jections

Isometri

Isometric c pr projection

• jection

Oblique

Oblique pr projection

• jection

TR TRUE UE PERSPECTIVE PERSPECTIVE

 Objec

Objects ts dr drawn awn in in tr true ue per perspect spectiv ive e look look r realist ealistic. ic.

 They have “vanishing

points” where straight lines seem seem to to con conver erge ge

 The

hey y ca can n ha have e on

• ne,

e, tw two

• or
• r

thr three ee va vanish nishing ing po points, ints, de depe pend nding ing on

• n ho

how w muc much h the the ar artist tist wan ants ts to to wor

• rk.

k.

 Bu

But t in in tr true ue per perspect spectiv ive, e,

• bjects
• bjects far

ar aw away wil ay will l be be dr drawn smaller awn smaller than nea than nearby rby

• bjects… not a good idea in

tec technic hnical al dr drawing awing!

Vanishing Point Vanishing Points Vanishing Points

MORE MORE TR TRUE UE PERSP PERSPECTIVE ECTIVE DRA DRAWINGS WINGS

ISOME ISOMETR TRIC IC PR PROJ OJEC ECTION TION

(A SIMULA (A SIMULATE TED D PE PERSPE RSPECTIV CTIVE E DR DRAWIN WING G ST STYLE) YLE)

 Iso

Isome metric tric (or (or simula simulated ted p per erspe spectiv ctive) e) dr drawing awings l s loo

• ok a

k at f t fir irst st li like pe e perspe spectiv ctive e drawings…

 But the lines don’t

co conver erge ge. . T The here e ar are e no no van vanishing ishing po points ints an and d distan distant o t objec bjects ts ar are th e the sa e same me siz size a e as s ne nearb arby on y ones. es.

 Ri

Righ ght a t ang ngles i les in n isome isometri tric c pr projec

• jections

tions ar are u e usu suall ally y rep eprese esente nted d by 6 by 60° or

• r

120 120° an angles. les.

60˚

Represents 90˚ Represents 90°

MO MORE RE ISOMETRIC ISOMETRIC DRA DRAWING WINGS

OBLIQUE OBLIQUE PR PROJECTION OJECTION

ANOTHER “SIMULATED” PERSPECTIVE

 Similar to isometric projection, it

is also a “simulated perspective”

 In oblique projections, the side

• f the object facing you is

drawn “square” and accurate (that is with right angles at 90° and its measurements proportional)

 The sides not facing you are

distorted

90°

90°

=60°

This side is accurate

This side is not!

OR ORTHOGRAPHIC THOGRAPHIC PR PROJECT OJECTIONS IONS

 Orthographic projections “flatten” one

vi view of ew of t the object he object onto a

• nto a shee

sheet t of

• f pa

paper per, , whil hile r e retaining the c etaining the cor

• rrec

ect t pr prop

• por
• rti

tion

• ns

s (ang (angles les and dim and dimensions) ensions)

 Ma

Maps ar ps are an e an example xample of

• f or
• rthog

thographic phic pr projection (a

• jection (a top view)

top view)

 The

he tr trouble w

• uble wit

ith h or

• rthog

thographic phic projections is that one view usually isn’t enough. enough.

 Ma

Maps and floor ps and floor-plans plans ar are e exceptions ceptions, , wher here one e one top top-view view is is often enough.

• ften enough.

ORTHOGRAPHIC PROJECTION

(MULTI-VIEW)

Draws an object as it

would be seen from several different directions

The views are “flat”,

with all angles shown correctly and all measurements to scale.

COMP COMPAR ARING ING PR PROJECT OJECTIONS IONS

 Per

erspect spectiv ive e dr drawings look awings look nicer nicer when used hen used by an by an ar artist, tist, but…

 Isometr

Isometric, ic, oblique

• blique and multi

and multi- view view dr drawings awings giv give e mor more e acc accur urate in te infor

• rma

mation tion when hen used used in tec in technical hnical dr drawing. awing.

 Isometr

Isometric ic dr drawings awings sho show w accur accurate dimensions, te dimensions, but but disto distorted ted ang angles. les.

 Oblique

Oblique dr drawings awings giv give e accur accurate dimensions te dimensions for

• r one
• ne

side side onl

• nly.

 Ortho

thographic phic (mu (multi lti-view) view) ar are e the best the best choice hoice for most

• r most

tec technical hnical dr drawing. awing.

Oblique Orthographic (multi-view)

AN ISOMETR AN ISOMETRIC IC DR DRAWING WING

SCALE SCALE

 SCA

SCALE LE is is the the rela elationship tionship betw between een the the meas measur uremen ement t of

• f an objec

an object t dr drawn awn on a

• n a

sh sheet eet of

• f pa

paper per, , and and the meas the measur uremen ements ts of

• f

the the actual actual object.

• bject.

 Often

Often tec technica hnical l dr drawing awings s ar are made e made a a dif differ erent ent siz size e fr from the

• m the objec
• bjects

ts they they repr epresen esent. t.

 Sca

Scale le-red educ uction tion is is whe hen n the d the draw awing ing is is sma smaller ller than than the the actua actual l objec

• bject

 Scale

Scale-incr increa ease se is is whe hen n the the dr drawing awing is is lar larger ger than than the actual the actual objec

• bject.

t.

DIMENSIONING DIMENSIONING

Whe

hen n a dr a drawing awing is is do done ne to to sc scale, ale, you

• u

sh shou

• uld

ld la labe bel l it wi it with th its its dimen dimension sions. s.

 Use

Use dimen dimension li sion line nes s to to la labe bel e l eac ach h dimen dimension, sion, with ith exte tension sions s where necessa ssary

 You

• u sho

should la uld labe bel just l just en enou

• ugh

gh ed edge ges s to to sho show all all th the e dimensions, but you don’t need to repeat.

 In

In Amer America ica dimen imension sions ar s are usu suall lly y giv iven i in mi mill llimetr metres es (mm). (mm). If If you

• u use

use dif differ eren ent t un units (c its (cm, m, mm, mm, fee eet, e t, etc tc.) y .) you

• u nee

need d to to w write rite th the un e unit.

• it. Ang

Angles les ca can n be be sho shown in n in de degree ees s (°), ), diameter diameter by by Ø, Ø, and and rad adius by ius by R

DIMENSIONING (SMALL TOY TRUCK)

300 means 300mm

unless another unit is specified

Ø means diameter (R would be radius)

A Toy Truck

How to label an angle. How to label small dimensions.

DIMENSIONING

Dimensions can also be shown on isometric drawings, but you have to be a bit more

• careful. Also, you

should only show the most important dimensions on an isometric drawing.

DIA DIAGRAM GRAMS

Diagrams are simplified versions of a

• drawing. Diagrams show how an object

works, not necessarily how it looks.

Diagrams often use abstract symbols rather

than actual pictures to represent things.

A CIR A CIRCUIT CUIT DIA DIAGRAM GRAM

 Doesn’t show what the circuit looks like, but

tell tells s an electr an electrician ho ician how w its its all connected. all connected.

DIAGRAM OF ENERGY CONVERSION UNIT

 It doesn’t show what the unit looks like, but rather,

wha hat t it it does or does or ho how w it it wor

• rks.

ks.

EXPLODED VIEWS

 A diagram that shows an object “taken apart” is

somet sometimes imes called an e called an exploded view xploded view.