General Sketching - Memorial University of Newfoundland

Engineering Graphics 1504 Lecture 2 General Sketching Objectives Lines Arcs Pictorial Types Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 1 Sketching Straight Lines Lightly mark endpoints of line. Lightly sketch from one endpoint to the other. Use 1 to 2 inch strokes, keeping eye on the second endpoint. DONT USE A STRAIGHT EDGE!

Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 2 Sketching Circles and Arcs Diameter Diameter The 2/3 method 2/3 of center distance PLUS SIGN MARKS CENTER SKETCH SQUARE SKETCH ARCS

FOR CIRCLE Course: Engineering Graphics 1504 Memorial University of Newfoundland SKETCH AND MARK DIAGONALS DARKEN CIRCLE Sheet 3 Pictorial Representation Illusion of three dimensions

Shows more information Easier to visualize Often used to explore ideas, aid explanation, present information Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 4 Three Types of Pictorial Sketches perspective Course: Engineering Graphics 1504 isometric Memorial University of Newfoundland

oblique Sheet 5 Perspective Drawings Represents what the eye sees Railway tracks come together Vanishing points Do not show true size or lengths.

Used to show artists conception Course: Engineering Graphics 1504 Memorial University of Newfoundland V A N IS H IN G P O IN T Sheet 6 Isometric Drawings Want to show more sides of the object in one view

Rotate 45 about vertical axis through centre Two views sides shown in front view Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 7 Isometrics Tip forward about the corner x

Top view now shows front, top, and side of cube Isometric if cube is tipped so that sides are of equal length and make angle of 30 to the horizontal 30o 35O 16 30o X Course: Engineering Graphics 1504 Memorial University of Newfoundland H O R IZ O N T A L

Sheet 8 Isometrics Isometric equality of measure All sides in an isometric drawing are drawn to actual size (close to truth) b 1 .0 0 1 .0 0 1 .0 0 1 .0 0 IS O M E T R IC Course: Engineering Graphics 1504

1 .0 0 n D IM E T R IC Memorial University of Newfoundland 1 .0 0 a T R IM E T R IC Sheet 9 Isometrics

Any line parallel to an isometric axis is measured as true length Any line not parallel to an axis is not true length Diagonals on a real cube are of equal length not the case here Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 10 Oblique Projection

Sometimes an isometric drawing may have features that are difficult or time consuming to represent (e.g. circle). If lines of sight through picture plane are at an angle other than 90, get oblique projection Front view drawn to normal size, other views are drawn at some angle (typically 30, 45, 60) Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 11 Oblique Projection Two common types of oblique projections are

cavalier and cabinet Front view is full size in both types but scale on receding axis is different IZ LL S FU C A V A L IE R Course: Engineering Graphics 1504 E L HA F S IZ E

C A B IN E T Memorial University of Newfoundland Sheet 12 Break Time Take 5 minute break Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 13 Making an Isometric Drawing Construct isometric

axes Block out space occupied by the shape Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 14 Making an Isometric Drawing Draw lines parallel to axes at key points No hidden lines are shown in a pictorial!

Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 15 Sketching Circles in Isometric Drawings A circle appears as an ellipse in isometric Locate centre by joining the corners and drawing diagonals Use same procedure as outlined for orthographic sketching Course: Engineering Graphics 1504 Memorial University of Newfoundland

Sheet 16 Class Assignment #3 Sketch an isometric of example 2.6 in text (freehand) Sketch an isometric of question #80 in Chapter 2 of the text (use instruments and scale to larger size) Course: Engineering Graphics 1504 Memorial University of Newfoundland Sheet 17