junior certificate: technical graphics notes

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TECHNICAL GRAPHICS (T.G.)JUNIOR CERTIFICATE EXAM GUIDANCE & REVISION NOTES

JOSEPH LYSTERLINE IT OUT ©PATRICIAN SECONDARY SCHOOL NEWBRIDGE, CO. KILDARE, REP. OF IRELAND.

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A. EXAM GUIDANCE [GENERAL]

1. FORMAT2. TIMING3. SUGGESTED APPROACH

B. TOPICS [SECTION A+B]

4. FIRST PRINCIPLES5. ORTHOGRAPHIC PROJECTION6. AUXILIARY PROJECTION7. ROTATION OF OBJECTS8. AXONOMETRIC PROJECTION9. DEVELOPMENT OF SURFACES / SOLIDS IN CONTACT10. TRANSFORMATION GEOMETRY11. CIRCLES IN CONTACT12. ELLIPSE & PARABOLA13. ENLARGEMENT & REDUCTION14. AREA OF FIGURES15. PERSPECTIVE16. SIMPLY INCLINED PLANES & CUT SURFACES

*NOT ALL SHORT QUESTION AREAS ARE COVERED IN THESE NOTES SO REFER TO EXAMPLES AS DONE IN CLASS AND IN EXAM PAPERS I.E. SKETCHING, TERMINOLOGY, C.A.D. COMMANDS, BAR/PIE/LINE CHARTS/GRAPHS ETC…

CONTENTS

FORMAT:

EXAM DURATION HIGHER LEVEL = 3 HOURS ORDINARY LEVEL = 2.5 HOURS

EXAM PAPER STRUCTURE TWO SECTIONS IN EXAM PAPER

SECTION A = MIXED TOPIC SHORT QUESTIONS FIFTEEN SHORT QUESTIONS (ANSWER ANY TEN – TRY ALL)

SECTION B = LONG QUESTIONS SIX LONG QUESTIONS (ANSWER ANY FOUR)

HIGHER LEVEL 1. ORTHOGRAPHIC PROJECTION 2. ROTATION OF OBJECTS 3. AXONOMETRIC OR ISOMETRIC SCALE 4. DEVELOPMENT OF SURFACES & SOLIDS IN CONTACT 5. TRANSFORMATION GEOMETRY 6. ELLIPSE, PARABOLA & CIRCLES

EXAM GUIDANCE

ORDINARY LEVEL 1. ORTHOGRAPHIC PROJECTION 2. ELLIPSE 3. DEVELOPMENTS 4. ISOMETRIC OR OBLIQUE 5. TRANSFORMATION GEOMETRY 6. CIRCLES

TIMING: HIGHER LEVEL

3 HOURS (180 MINUTES) SPEND 3 TO 5 MINUTES PREVIEWING EXAM PAPER AT START SECTION A: RECOMMENDED TIME = 45 MINUTES MAX [35 MINUTES OR LESS WOULD BE

IDEAL] SECTION B: RECOMMENDED TIME = 130 MINUTES MAX (32.5 TO 35 MIN/QUESTION) KEY TIP: WHEN STUDYING, GET INTO THE HABIT OF DOING QUESTIONS RELATIVE TO THE

TIMING SUGGESTED. WHEN IN THE EXAM, HAVE TIME QUES OR BE VIGILANT OF TIME DURING THE EXAM TO REMIND YOU TO PROGRESS FROM ONE QUESTION TO ANOTHER.

ORDINARY LEVEL 2.5 HOURS (150 MINUTES) SPEND 3 TO 5 MINUTES PREVIEWING EXAM PAPER AT START SECTION A: RECOMMENDED TIME = 25 TO 30 MINUTES MAX SECTION B: RECOMMENDED TIME = 120 MINUTES MAX (30 MIN/QUESTION) KEY TIP: WHEN STUDYING, GET INTO THE HABIT OF DOING QUESTIONS RELATIVE TO THE

TIMING SUGGESTED. WHEN IN THE EXAM, HAVE TIME QUES OR BE VIGILANT OF TIME DURING THE EXAM TO REMIND YOU TO PROGRESS FROM ONE QUESTION TO ANOTHER.

EXAM GUIDANCE

SUGGESTED APPROACH: BE ‘SMART’… DON’T PANIC, EASY FOR ME TO SAY BUT REALLY DON’T PANIC. THE EXAM PAPER WILL

LOOK DIFFERENT BECAUSE ALL OF THE QUESTIONS ARE NEW AND PREVIOUSLY UNSEEN. TAKE A MINUTE TO RELAX AND THEN CONFIRM TO YOURSELF THAT YOU ARE REFINED IN THE METHODS /UNDERSTANDING TO ANSWERING SUCH QUESTIONS. REMEMBER THAT YEAR ON YEAR THE FACE OF THE QUESTIONS MAY CHANGE BUT THE DETAIL IS THE SAME, THE METHODS ARE CONSISTENT AND THERE IS A LOGICAL SEQUENCE TO BE FOLLOWED IN ALL CASES.

UPON REVIEW OF EXAM PAPER, MARK THE QUESTIONS YOU FEEL MOST CONFIDENT ABOUT DOING

DO SECTION ‘A’ FIRST AND BEGIN WITH WHATEVER QUESTION YOU FEEL YOU CAN ANSWER BEST. MAKE SURE YOU HAVE ATTEMPTED AT LEAST 10 SHORT QUESTIONS THOUGH I DO RECOMMEND THAT YOU DO ALL FIFTEEN IF POSSIBLE.

MOVE ONTO SECTION ‘B’ AND AGAIN BEGIN WITH YOUR STRONGEST QUESTION, I.E. THE ONE YOU KNOW YOU CAN DO BEST IN THE LEAST AMOUNT OF TIME!

BE MINDFUL OF TIME…AS PREVIOUSLY MENTIONED. IN ALL CASES, REMEMBER TO DOUBLE CHECK WHAT THE QUESTION IS ASKING YOU. IT

IS NOT UNCOMMON TO PRESUME SOMETHING OR OVERLOOK SOMETHING. BE DILLIGENT HERE.

IF ALL ELSE FAILS JUST HAVE A GO. IT CAN DO NO HARM TO HAVE A GO. IF YOU HAVE TIME AT THE END, SPEND IT BY REVIEWING THE WORK YOU HAVE DONE

OR TIDYING UP/FINISHING INCOMPLETE QUESTIONS DO NOT LEAVE THE EXAM HALL WITHOUT HAVING ATTEMPTED THE

REQUIRED AMOUNT OF QUESTIONS TO THE BEST OF YOUR ABILITY.

EXAM GUIDANCE

MAKE SURE YOU HAVE ALL OF THE

REQUIRED DRAWING

EQUIPMENT WITH YOU FOR THE

EXAM!!!

EXAM GUIDANCE

OVERVIEW

FIRST PRINCIPLES

FIRST PRINCIPLES

FIRST PRINCIPLES

PENTAGON [360/5 = 72°]

HEXAGON [360/6 = 60°]

OCTAGON[360/8 = 45°]

FIRST PRINCIPLES

BISECTING A LINE[STEPS]

FIRST PRINCIPLES

BISECTING AN ANGLE [STEPS]

FIRST PRINCIPLES

OVERVIEW

ORTHOGRAPHIC PROJECTION

WE DRAW USING ‘FIRST ANGLE’ PROJECTION AND IN THE CONTEXT OF D.C.G. ORTHOGRAPHIC PROJECTION IS FUNDAMENTAL TO ALL TOPIC AREAS, JUST AS PARAGRAPHS ARE IN THE STRUCTURING OF AN ENGLISH ESSAY.

ORTHOGRAPHIC PROJECTION ALLOWS US TO SYSTEMATICALLY ARRANGE MUTLIPLE VIEWS OF A GIVEN OBJECT/STRUCTURE ETC IN A MANNER THAT ALLOWS FOR COMMON INTERPRETATION.

WE HAVE THREE TYPICAL VIEWS, NAMELY ELEVATION [FRONT VIEW], PLAN [TOP VIEW] & END VIEW [SIDE VIEW].

WE ALSO HAVE AUXILIARY VIEWS, OF WHICH WE CAN HAVE AN AUXILIARY PLAN VIEW OR AN AUXILIARY ELEVATION VIEW. WE WILL CLARIFY BOTH FURTHER ON IN THESE STUDY NOTES.

IN CONSIDERATION OF STANDARD ORTHOGRAPHIC VIEWS, THIS EXIST ON THE VERTICAL AND HORIZONTAL PROJECTION PLANES.

WE ALSO HAVE AUXILIARY PLANES, SIMPLY INCLINED PLANES, OBLIQUE PLANES AND AXONOMETRIC PLANES THAT ALL FACILITATE VARIOUS FORMS OF TECHNICAL PRINCIPLES AND GEOMETRY.



ELEVATION

PLAN

END VIEW

ORTHOGRAPHIC PROJECTIONDEALING WITH CURVED SURFACES IN ORTHOGRAPHIC

OVERVIEW

AUXILIARY PROJECTION

STANDARD AUXILIARY PROJECTION AUXILIARY PROJECTION IS THE CREATION OF AN

ALTERNATIVE VIEW OF A GIVEN OBJECT WITHIN THE CONTEXT OF HORIZONTAL, VERTICAL AND AUXILIARY PLANES.

IN JC TECHNICAL GRAPHICS THEY APPEAR IN SHORT ANSWER QUESTIONS AS WELL AS ANY OF THE LONG QUESTIONS, DEPENDING ON WHETHER THERE IS A NEED TO USE AN AUXILIARY OF NOT.

THEY CAN BE COMMONLY USED TO FIND ALTERNATIVE VIEWS OF OBJECTS AND TRUE SHAPES OF PARTICULAR SURFACES

THE KEY TO THE AUXILIARY PROJECT IS IDENTIFYING THE ANGLE OF PROJECTION FROM EITHER ELEVATION, PLAN OR INDEED END VIEW. IN MOST CASES, IF YOU ARE TRYING TO FIND THE TRUE SHAPE OF A SURFACE LOOK FOR THE VIEW OF THAT SURFACE WHERE IT APPEARS TO BE A SINGLE LINE (EDGE VIEW). FROM THERE YOU CAN SET UP YOUR X1Y1 PARALLEL TO THAT LINE AND PROJECT FROM THERE.

STANDARD AUXILIARY PROJECTION

AUXILIARY ELEVATION

AUXILIARY PLAN

AUXILIARY ELEVATION:PROJECT FROM PLAN AND TAKE MEASUREMENTS FROM ELEVATION

AUXILIARY PLAN:PROJECT FROM ELEVATION AND TAKE MEASUREMENTS FROM PLAN

AUXILIARY PROJECTIONAUXILIARY ELEVATION

AUXILIARY PROJECTIONSNAPSHOT OF AN AUXILIARY ELEVATION BEING USED IN SOLIDS IN CONTACT

OVERVIEW

ROTATION OF OBJECTS

ROTATION OF OBJECTS

OVERVIEW

DEVELOPMENTS & SOLIDS IN CONTACT (S.I.C.)

DEVELOPMENT & S.I.C.

OVERVIEW

AXONOMETRIC PROJECTION

AXONOMETRIC PROJECTIONTYPE 1: ISOMETRICAXONOMETRIC PLANE IS AN EQUILATERAL TRIANGLEIN QUESTION ASSUME AS NORMAL

AXONOMETRIC PROJECTIONISOMETRIC

OVERVIEW

SCALED ISOMETRIC

SCALED ISOMETRICISOMETRIC

OVERVIEW

SIMPLY INCLINED AND OBLIQUE PLANES

SIMPLY INCLINED PLANES

SIMPLY INCLINED PLANEEXAMPLE

OVERVIEW

AREAS OF FIGURES

AREAS OF FIGURES

OVERVIEW

PERSPECTIVE PROJECTION

PERSPECTIVE PROJECTION

OVERVIEW

CIRCLES

CIRCLES

OVERVIEW

ELLIPSE AND PARABOLA


ELLIPSE BY CONCENTRIC CIRCLES METHOD

PARABOLA BY RECTANGLE METHOD

CLASSIFICATION OF CONIC SECTIONS

OVERVIEW

TRANSFORMATION GEOMETRY

TRANSFORMATION GEOMETRY

ENLARGEMENT & REDUCTION

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