7/2/22, 10:42 AM Isometric Sketching Isometric Sketching https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 1/11 7/2/22, 10:42 AM Isometric Sketching An isometric view is used to realistically represent an object and communicate details that are difficult to describe in words. When an isometric view is drawn by hand, we call it an isometric sketch. In an isometric sketch, the object appears three-dimensional—three sides of the object are shown, and the size and location of features on the object are proportional to the real thing. Notice in the isometric view of the cube in Figure 1 that three sides are visible. The primary dimensions in an isometric view are labeled—width, depth, and height. The width and depth lines are oriented at a 30-degree angle from horizontal, as shown. If you measure the width, depth, Figure 1. Isometric View of a Cube and height of an object in an isometric view, the measurements will reflect the proportions of the real object. The orientation of the sketched object in your isometric view is important. Because only three sides of the object are visible, you should orient (turn the object in the sketch) so that as much information as possible is shown on the three visible sides. In this course, we will always orient the object in an isometric sketch so that the front of the object is turned toward the lower-left corner of the drawing, as shown in Figure 1. https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 2/11 7/2/22, 10:42 AM Isometric Sketching Note: Learn more about identifying the front of an object and choosing the best isometric orientation in the Isometric View Orientation resource. Isometric Sketch Characteristics Sketch appears three-dimensional because three sides are shown All principal dimensions (width, depth, and height) are represented in true proportion Width and depth lines are drawn at 30 degrees from the horizontal lines All height lines are vertical The shapes of the object faces are distorted (not represented as true shapes) Figure 2. Isometric Sketch Example https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 3/11 7/2/22, 10:42 AM Isometric Sketching Developing realistic sketches requires a sense of proportion. You must accurately represent the size, angles, and other spatial relationships of the real object. Note: Isometric graph paper can make sketching isometric views easier. The width and depth grid lines are oriented at the correct 30degree angle, and the grid spacing helps you correctly represent lengths along the three primary axes so that proportions are accurate. Isometric Sketch Example: Form 1 https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 4/11 7/2/22, 10:42 AM Isometric Sketching Figure 3. Isometric Sketch of Form 1 Isometric Sketch Example: Form 2 https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 5/11 7/2/22, 10:42 AM Isometric Sketching https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 6/11 7/2/22, 10:42 AM Isometric Sketching Figure 4. Isometric Sketch of Form 2 Scale Isometric pictorials are drawn in proportion so that the relationships among the size, shape, and position of the different parts of an object are accurately represented. If we represent an object in a drawing using the actual size and shape of the object, we say that the drawing is full scale. So, if you create a full-scale drawing of a 2-inch cube, you draw each edge of the cube 2 inches long. We often reduce the size of an object in a drawing when the object is large, or enlarge the object in a drawing if the object is small. For example, the chair as represented in the isometric sketch in Figure 5 is much smaller than the real chair, but the size and shape in the drawing is proportional—it resembles the real chair. If we reduce or enlarge the size of the object in a drawing, we refer to the drawing as a scale (or scaled) drawing. Figure 5. Scaled Isometric Sketch To draw a scaled drawing or sketch, we use a ratio to indicate the amount by which the drawing is enlarged or reduced. The scale of a drawing is shown on the drawing and is often represented as a pair of numbers separated by a colon. https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 7/11 7/2/22, 10:42 AM Isometric Sketching drawing size : actual size 1:5 The first number represents the length of the object as shown in the drawing, and the second number represents the actual length of the object. We can also think of this ratio as a fraction, 1/5 . The scale of the scaled drawing of the chair (Figure 5) is 1 : 5, which means that if you measure the height of the seat on the chair in the drawing as 3.5 inches, the height of the real chair seat is five times that length, or 17.5 inches (= 5 x 3.5 inches). Scaling a Sketch You can create a sketch that is larger or smaller than the actual object by scaling the sketch. One way to scale a sketch is to use grid paper, but assign a grid spacing different than the actual measurement between grid lines. The grid lines on the isometric graph paper provided should be spaced at approximately 1/4 inch. However, if we assign a grid spacing of 1/2 inch for our sketch (even though we know the lines are actually spaced at 1/4 inch) the sketch will appear smaller than the object. Conversely, if we assign a grid spacing of 1/8 inch, the drawing will be larger than the real object. https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 8/11 7/2/22, 10:42 AM Isometric Sketching Scaling a Sketch Example Using 4 x 4 graph paper (that is, 4 grids per inch in both directions), assign a grid spacing of 1/2 inch. If an edge on the real object is 3 inches long, you will sketch the edge 6 spaces long. You can verify this mathematically by: (6 spaces)(1/2 in./space) = 3 in. If you measure the line on the graph paper with a ruler, the line will measure 1.5 inches long. Therefore, the scale of the drawing is: Isometric Sketch Example: Scaled Form 3 A scaled isometric sketch of Form 3 is shown in Figure 6 on isometric graph paper. The actual form is constructed of six 1-inch cubes. https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 9/11 7/2/22, 10:42 AM Isometric Sketching Figure 6. Scaled Isometric Sketch of Form 3 RESOURCES Isometric Graph Paper https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 10/11 7/2/22, 10:42 AM Isometric Sketching https://pltw.read.inkling.com/a/b/bb056097750145349ef152dbbb4e5de2/p/9ba4e956cbe541dbade6730f2efd3b73 11/11
