AutoCAD 2D I Module 16 Isometric and Dimensioning PREPARED BY IAT Curriculum Unit January 2011 Institute of Applied Technology, 2011
Module 16 Auto CAD Self-paced Learning Modules AutoCAD 2D Isometric and Dimensioning Learning Outcomes: When you have completed the module, you will be able to: 1. recognize isometric and oblique drawings. 2. sketch isometric and oblique drawings of simple components. 3. Describe the basic dimensions terms. 4. Describe how to control and modify the appearance of dimensions. Isometric Projection Isometric drawings consist of two-dimensional drawings that are tilted at some angle to expose other views and give the viewer the illusion that what he or she is viewing is a three-dimensional drawing. The tilting occurs with two 30 angles that are struck from the intersection of a horizontal baseline and a vertical line (see Figure 16 1).The directions formed by the 30 angles represent actual dimensions of the object; this may be either the width or depth. The vertical line in most cases represents the height dimension. Figure 16-1 An Isometric Drawing Module 16: Isometric and Dimensioning 2
Figure 16 2 is a very simple example of how an object is aligned to the isometric axis. Figure 16-2 CREATING AN ISOMETRIC GRID Figure 16 3 shows the current AutoCAD screen complete with cursor and grid on. Figure: 16-3 Module 16: Isometric and Dimensioning 3
The display screen in Figure 16 4 reflects the use of the SNAP command and how this command affects the current grid display: Command: SN (For SNAP) Snap spacing or ON/OFF/Aspect/Rotate/Style <0.2500>: S (for Style) Standard/Isometric <S>: I (for Isometric) Vertical spacing <0.5000>: (Press ENTER_to accept default value) Figure: 16-4 ISOPLANE MODES: The AutoCAD cursor has always been the vehicle for drawing objects or constructing Windows for object selection mode. Once in isometric snap mode, AutoCAD Supports three axes to assist in the construction of isometric drawings. The first axis is the Left axis and may control that part of an object falling into the left projection plane. The next isometric axis is the Top mode Objects falling into the top projection plane Module 16: Isometric and Dimensioning 4
The final isometric axis is called the Right mode and is formed by the intersection of a vertical line and a 30 angle drawn off to the right. ISOMETRIC AIDS IN THE DRAFTING SETTINGS DIALOG BOX Choosing Drafting Settings from the Tools pull-down menu in Figure A 16A displays the Drafting Settings dialog box in Figure A 16B. Here, in addition to Snap and Grid, an Isometric area exists to automatically set up an isometric grid by clicking in the radio button next to Isometric Snap. This has the same effect as using the SNAP-Style-Isometric option. Figure A 16A Figure A 16B Module 16: Isometric and Dimensioning 5
AutoCAD User Must Know No. 16-1 When using Isometric snap, the crosshairs is always oriented with the specified isoplane. The isoplane does not apply to window or crossing selection and similar operations that use a box to make a selection. Various methods exist to switch from one isometric axis mode to another. By default, after you set up an isometric grid, the Left isometric axis mode is active. When you press CTRL+E, the Left axis mode changes to the Top axis mode. Pressing CTRL+E again changes from the Top axis mode to the Right axis mode. Pressing CTRL+E a third time changes from the Right axis mode back to the Left axis mode, and the pattern repeats from here. Using this keyboard entry, it is possible to switch or toggle from one mode to another. The F5 function key also allows you to scroll through the different Isoplane modes. CREATING ISOMETRIC CIRCLES: Circles appear as ellipses when drawn in any of the three isometric axes. The ELLIPSE command has a special Isocircle option to assist in drawing isometric circles; the Isocircle option will appear in the ELLIPSE command only if the current SNAP-Style is Isometric. Command: EL (For ELLIPSE) Arc/Center/Isocircle/<Axis endpoint 1>: I (for Isocircle) Center of circle: (Select a center point) <Circle radius>/diameter: (Enter a value for the radius or type D for diameter and enter a value). Fig. 16.5 Module 16: Isometric and Dimensioning 6
BASIC ISOMETRIC CONSTRUCTION: Any isometric drawing, no matter how simple or complex, has an overall width, height, and depth dimension. Start laying out the drawing with these three dimensions to create an isometric box illustrated in the example in Figure 16 6A. With the box as a guide, begin laying out all visible features in the primary planes. Use the Left, Top, or Right isometric axis modes to assist you in this construction process. See Figure 16 6B. Figure 16 6A Figure 16 6B Activity 1-1 Access the LINE tool and use grid and snaps to draw the isometric view shown below. Change the isoplane orientation as appropriate for drawing objects on each isometric plane. Do not dimension the drawing. 0.5 1.5 0.5 1.8 1.5 Save the drawing as ATSE 1. Module 16: Isometric and Dimensioning 7
Activity 13-2 For each of the following isometric drawings, start a new drawing that includes active isometric grid and snap modes. Draw an isometric part view similar to each drawing. Save the drawing as ATSE 2. Save the drawing as ATSE 3. Module 16: Isometric and Dimensioning 8
Save the drawing as ATSE 4. Save the drawing as ATSE 5. Module 16: Isometric and Dimensioning 9
Dimensioning AutoCAD does semi-automatic dimensioning You select the features which should be dimensioned and the location for each dimension AutoCAD measures the distance in question and applies the appropriate dimension complete with arrowheads, extension lines, and dimension lines The Dimensioning Toolbar: The dimensioning commands can be easily accessed by: Right Click on an existing toolbar and activate the dimensioning toolbar; Or, From the pull down menu View Toolbars. Dimension Terminology Linear Dimensions: They can be orientated either in a horizontal or vertical (or even aligned) fashion AutoCAD will automatically measure the length. Leaders: Leaders begin at the arrow and continue from their elbow to their annotation Radius and Diameter: By selecting a circular feature (arc or circle) with the Radius or Diameter option.90 DIMENSION LINE 1.80 3.00 1.00 EXTENSION LINE LEADER ARROWHEAD.80 EXTENSION LINE: EXTENSION GAP 2.00 1.00 1.20 Module 16: Isometric and Dimensioning 01
Special Characters in AutoCAD: %%c will show as the Diameter symbol: Ø %%d will show as the Degree symbol: %%p will show as the Plus-minus symbol: Dimension Style Manager Start the DIMSTYLE command, which opens the Dimension Style Manager dialogue box. Press then enter a name for your new style. Styl1 as an example. Press then Press Select styl1 and press Module 16: Isometric and Dimensioning 00
Now, select the style1 and press Modify The Modify Dimension Style dialogue box opens. In the Lines tab, you can change the color, line type and line weight of the dimension lines and the extension lines as well. You can set Extend beyond dimension line and Offset from origin. + The Length is (1+ 2) Module 16: Isometric and Dimensioning 02
Now select the Symbols and Arrows tab in which you have the following options. You can change the shape of the arrowheads. Module 16: Isometric and Dimensioning 03
The Text tab controls the appearance of the text in the entered dimensions. Press this to create a new text You can change the Text format (new text style, font name like Arial, font style like Bold). Module 16: Isometric and Dimensioning 04
The Primary Units tab allows controls the appearance of the dimensioning units. Then 3. Summary press OK, and Module set current. 7 1. An isometric drawing is a 2-dimensional drawing that has the XYZ axis drawn 120 degrees apart. Module 16: Isometric and Dimensioning 05
Lab Exercise 13-1 Time Allotted: 50 min. Drawing Specifications Name Template Units Text Style Font AutoCAD 2D Lab 13-1 Module Template A3 millimeter N/A N/A Note: Color, Linetype and Lineweight are all ByLayer unless otherwise instructed. Layering Scheme Objects on Layer Name Color Linetype Lineweight Construction Objects Construction 253 Continuous N/A All Objects Object White/Black Continuous N/A Hidden Hidden Red Dashed N/A Dimension Dimension Blue Continuous N/A Center line Center Blue Center N/A Instruction: 1. Setup the layers. 2. Draw the object shown below ( Isometric and views ). 3. Draw all dimensions on the views. 4. Check your drawing with the key. Module 16: Isometric and Dimensioning 06
10 20 5 40 10 20 40 30 10 65 15 40 35 20 10 AutoCAD 2D-I Lab Exercise 13-1 Time Allotted: 50 min. Drawing Specifications Name Template Units Text Style Font AutoCAD 2D Lab 13-1 Module Template A3 millimeter N/A N/A Note: Color, Linetype and Lineweight are all ByLayer unless otherwise instructed. Layering Scheme Objects on Layer Name Color Linetype Lineweight Construction Objects Construction 253 Continuous N/A All Objects Object White/Black Continuous N/A Hidden Hidden Red Dashed N/A Dimension Dimension Blue Continuous N/A Center line Center Blue Center N/A Instruction: 5. Setup the layers. 6. Draw the object shown below. 7. Draw all dimensions on the views. 8. Check your drawing with the key. 15 20 15 30 30? 10 R5 40 10 65 60 20 30 15 20 60 Module 16: Isometric and Dimensioning 07
4. Suggestions for practice 1. What is the correct angle for the drawing of isometric axis? A. 40 B. 60 C. 30 D. 15 2. A dimension controls the way the dimensions appear in your drawing. A. menu B. style C. line D. tool Module 16: Isometric and Dimensioning 08