PICTORIAL DRAWINGS

PICTORIAL DRAWINGS Topic / Objectives: Pictorial Drawings Identify types of pictorial drawings. Centering isometric, cavalier, & cabinet drawings. Sketch & draw isometric drawings using an isometric object. Sketch & draw isometric drawings using a multiview drawing. Draw a cavalier, cabinet, & two point perspective drawings.

PICTORIAL DRAWINGS When we view large objects in a room or outdoors, we generally see them as a perspective view. In a perspective drawing objects are small as they get further away. One way to represent this on paper is a 2-point perspective drawings. Lines trailing off into the distance converge to a point.

When we view most smaller items from a far enough distance the perspective is hard to notice. There is an easier way to represent these objects with an Isometric Drawing.

ISOMETRIC DRAWINGS The object is held with one vertical edge, then tilted toward the viewer until the other horizontal edge are at a 30 degree angles. All three axes are scaled equally at 120 degrees. Since all lines are parallel, isometric drawings can be created quickly.

Isometric and Non-isometric lines & planes In an isometric drawing, true length distances can only be measured along isometric lines, that is, lines that run parallel to any of the isometric axes. Any line that does not run parallel to an isometric axis is called a non-isometric line Non-isometric lines include inclined and oblique lines and can not be measured directly. Instead they must be created by locating two end points.

Drawing of Circle and Arcs In isometric drawing, a circle appears as an ellipse. Sketching Steps 1. Locate the center of an ellipse. 2. Construct an isometric square. 3. Sketch arcs that connect the tangent points.

Drawing of Circle and Arcs Isometric Drawing Drawing of Circle and Arcs Four-center method is usually used when drawn an isometric ellipse with drawing instrument. Sketching Steps 1. Locate the center of an ellipse. 2. Construct an isometric square. 3. Construct a perpendicular bisector from each tangent point. 4. Locate the four centers. 5. Draw the arcs with these centers and tangent to isometric square.

Drawing of Circle and Arcs The fastest and most accurate way to draw an ellipse for an isometric drawing is to use an ellipse template.

Hidden Lines Hidden lines are not usually shown in isometric sketches unless they are needed to show a feature that would be unclear. Usually the orientation for the isometric drawing should be chosen so that hidden lines aren’t needed. Holes are assumed to go completely through the object unless their depth is indicated with a note or with hidden lines.

IDENTIFING PICTORIALS DRAWINGS ISOMETRIC CAVALIER CABINET TWO-POINT PERSPECTIVE

CAVALIER & CABINET DRAWINGS

CAVALIER & CABINET DRAWINGS Cavalier drawings are drawn with the full depth. Reason for doing a cavalier drawing: Accurate dimensions. Cabinet drawings are drawn with a shortened(1/2) depth. They get their name from the furniture industry. Reasons for doing cabinet drawing: More natural look. Sometimes shows more detail.

PERSPECTIVE & OBLIQUE

Centering an Isometric Drawing After drawing the border and title block find the center of the workspace. Starting at the center of the workspace draw a 30 degrees line down to the right half the length of the object. From the end of the first line draw a 30 degree line to the left half the width of the object. From the end of the second line draw a 90 degree line down half the height of the object. Start drawing the overall isometric box for the object from the last point. X 30° half the length 30° half the width 90° half the height

Centering an Isometric Object What are the measurements needed to center this object as an isometric drawing? The length of the object. The width of the object. The height of the object. X 30° half the length = 3” 30° half the width = 2 ¼” 90° half the height = 1 13/16”

Essential Questions: •What is an isometric drawing? A pictorial drawing of an object positioned so that all three axes make equal angles(120 degrees) with each other. •How do you center an isometric drawing? Starting from the center of the workspace: (1) draw a 30° line to the right half the length of the object (2) draw a 30° line to the left half the width (3) draw a line straight down half the height of the object. •What is the difference between a cavalier and cabinet drawings? A cavalier drawing goes back the full size of the width of the object while the cabinet drawing only goes back half the width. The cabinet drawing looks better proportionally than the cavalier drawing.