Technical Graphics

Second Year Homework 08/Sept/17

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Technical Graphic is one of two Technology subjects offered to students in CBS Wexford.  In Technical Graphics students learn to represent real life 3 dimensional objects in 2D on paper or the computer.

 THIRD YEAR NOTES:

Section A:  Short Questions

PERSPECTIVE

All parallel line vanish to the same vanishing point.

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The diagrams below are a breakdown of the solution to the perspective short question in 2016.  It was Question 2 in Section A.

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The diagrams below are a breakdown of the solution to the perspective short question in 2015.  It was Question 2 in Section A.

JCHLSA15Q2 JCHLSA15Q2a JCHLSA15Q2b JCHLSA15Q2c JCHLSA15Q2d JCHLSA15Q2e JCHLSA15Q2f JCHLSA15Q2g JCHLSA15Q2h JCHLSA15Q2i JCHLSA15Q2j JCHLSA15Q2k JCHLSA15Q2l JCHLSA15Q2m JCHLSA15Q2n JCHLSA15Q2o JCHLSA15Q2p JCHLSA15Q2q JCHLSA15Q2r JCHLSA15Q2s JCHLSA15Q2t

Perspevtive Storyboards:

Section A, 2013

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FREEHAND SKETCHING

This style of question appears as two in Section A every year.  One of these questions will provide a grid.  Both must be completed freehand and shaded to pick up all the marks available.

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AREA CONVERSIONS

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TANGENTS TO A POINT ON A CIRCLE

To draw a tangent to a circle at a given point on the circumference of a circle.

First draw a line from the centre of the circle through the point of contact.  This line is the called the normal.  It is at 90° to the tangent.

TG Tangent to a Circle Image 01

Now to draw a line through the point of contact that is at 90° to the normal.  This is the tangent to the circle at point P.

TG Tangent to a Circle Image 02

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To draw a tangent to a circle from a given point outside the circumference of a circle.

The construction of a tangent to a circle from a point outside the circumference of the circle is based on the angle in a semicircle theorem.   To draw the tangent first draw a line from the point Q to the centre of the circle.

TG Tangent to a Circle Image 03

Now bisect the distance between the centre and Q.

TG Tangent to a Circle Image 04

This finds the centre of a semicircle that passes through C and Q.  Draw a semicircle passing through these points.

TG Tangent to a Circle Image 05

This semicircle cuts the circle at the point of contact between the tangent and the circle. Label the point of contact P.

TG Tangent to a Circle Image 06

Once P, the point of contact, has been found then draw the tangent through the points Q and P.

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The diagrams below are a breakdown of the solution to the Tangent short question in 2016.  It was Question 14 in Section A.

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Tangents to Circle Storyboards:

Tangents:  Section A,  2013

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CIRCLES IN CONTACT/ DIVISION OF LINES

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Circles d CLEANED

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CONIC SECTIONS

The diagram below shows the solution to the Conic Sections short question in 2016.  It was Question 1o in Section A.

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Conic Sections Storyboards

TG Conic Sections Storyboard 1

TG Conic Sections Storyboard 2

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CAD COMMANDS

This CAD commands question is generally in Section A every year.  The diagrams below are the solutions to the CAD short question in 2015, 2016.  It was Question 9 in Section A.

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ORTHOGRAPHIC PROJECTION AND AUXILIARY VIEWS

This topic is generally in Section A every year.  The diagrams below are the solutions to the question in 2016.  It was Question 9 in Section A.

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 SOLIDS IN CONTACT

This question is generally in Section A every year.  The diagrams below are the solutions to the short question in 2016.  It was Question 11 in Section A.

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REDUCING AND ENLARGING

Reducing and Enlarging Storyboards

TG Reducing By Polar Projection

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Section B:  Long Questions

ORTHOGRAPHIC PROJECTION

This topic appears in Section B of the Technical Graphics higher level paper.  It is generally Question 1.  This question will include the construction of a plan, elevation and end-view of a given object.  These object will usually contain a cut cylinder.  Also a true shape of on of the surfaces is generally required.

Click the title to move to the Orthographic Projection Page.

ROTATION OF SURFACES

This topic appears in Section B of the Technical Graphics higher level paper.  It is generally Question 2.  This question will include the construction of a plan, elevation and end-view of a given object.  These object will contain a surface that is rotated around a hinge.  Drawing this surfaces in its rotated position is generally required.

Click the title to move to the Orthographic Projection Page.

TRANSFORMATION GEOMETRY

This topic appears in Section B of the Technical Graphics higher level paper.  It is generally Question 5.  This question will include the construction of a logo or image and four transformations of this image.  These transformations will be a translation, axial symmetry, central symmetry and a rotation.

Click the title to move to the Transformation Geometry Page.

CONIC SECTIONS

Click the title to move to the Transformation Geometry Page.