AutoCAD 2D Lesson 1 Getting Started Pre-reqs/Technical Skills Basic computer use Expectations Read lesson material Implement steps in software while reading through lesson material Complete quiz on Blackboard Submit completed assignment on Blackboard Attend help sessions as necessary Post comments on lesson web page Objectives/Measurables Learn the basics of using AutoCAD to create simple 2D drawings, measured via assignment score Learn various features in AutoCAD, measured via Blackboard quiz score Lecture Topics Opening AutoCAD Basic drawing Table of Contents AutoCAD 2D... 1 Lesson 1 Getting Started... 1 Pre-reqs/Technical Skills... 1 Expectations... 1 Objectives/Measurables... 1 Lecture Topics... 1 Introduction AutoCAD 2010,2011... 1 Opening AutoCAD... 2 Getting Help... 2 Basic Drawing... 3 Lines... 3 Snaps... 5 Zooming... 7 Deleting... 7 Circles and Other Drawing Elements... 9 Trimming... 9 Assignment... 11 Introduction AutoCAD AutoCAD is a 2D and 3D computer aided drafting (CAD) program. It is used primarily for mechanical and architectural drafting. Essentially, it provides a computer-based method for producing engineering drawings. The 2010+ versions integrates the Windows Ribbon interface which may be unfamiliar to those who have used earlier versions. This module uses the default Ribbon interface and is designed for those new to AutoCAD or those who wish to use the new Ribbon interface. 1
Opening AutoCAD AutoCAD can be started from Start (or the Windows button) ->(All) Programs -> Autodesk - >AutoCAD 20xx -> AutoCAD 20xx English. On campus computers there should be a desktop shortcut. Autodesk makes the most recent versions of some of their industrial software (such as AutoCAD) freely available to students. If you would like to look into this program, go to this website: http://students.autodesk.com/. Installs of Autodesk software on personal computers will not be officially supported but can be used to complete assignments. One the first launch of AutoCAD, you will be presented with the Welcome dialog as shown in Figure 1. You may close the dialog. Figure 1 - Welcome Getting Help After completing the initial setup, you will be presented with an interface similar to the one shown in (Figure 2). To access AutoCAD help, use the help search bar (highlighted in red) or click the help button (the circle with a question mark). 2
Figure 2 - AutoCAD 2010 Interface and Help Basic Drawing These tutorials focus on the 2D drawing aspects of AutoCAD. For 3D solid modeling, the NX module is recommended. The general workflow for making a drawing in AutoCAD is to place drawing elements such as lines and circles in the model space, these elements can then be edited (trimmed, extended, copied, etc.), the drawing can then be dimensioned and moved to layout space for printing. This tutorial covers the basics of drawing and some editing commands. All work will be done in the model space. Model space is opened by default. The various drawing spaces can be changed using the tabs at the bottom of the workspace (Figure 3). Also shown in Figure 3 is the axis indicator (the arrows with X and Y). These axes show the directions for the 2D coordinate vectors. Figure 3 - Model Space Lines The start drawing, select the Line button in the Draw pane of the Home tab (Figure 4). 3
Figure 4 - Drawing Tools This will change the cursor to the line start point cursor (Figure 5). To set the first point of a line, you can type in coordinates or just click in the workspace. To type in coordinates, enter the first decimal number (1.0 for example) for the x-coordinate (the distance from the origin along the x-axis with positive numbers being to the right and negative to the left). Type a comma to finish the x-coordinate and move to the y-coordinate. This will lock in the x and allow you to type in the y value (Figure 6). Hit Enter to start the line at the coordinates entered. Figure 5 - Entering the x-value Figure 6 - Entering the y-value With the first point set, AutoCAD defaults to polar coordinates (Figure 7) for the next point (angle and length of the line). To change the angle, move the cursor around until the angle changes to the value needed. Enter the length of the line using the keyboard then hit enter to set the point. Alternatively, you can type in x and y values for the next point by typing in the x value, then typing a comma to switch to the y value. The x and y values you type are relative to the last point, not the origin (i.e. if you start a line at (0,0), then set the next point at (0,2) and then another point at (0,2) the last point will actually be at (0,4) relative to the origin (0,0)). Once you set the endpoint of a line, AutoCAD immediately starts another line at that endpoint. This allows you to create multiple connected lines without having to click the Line button each time. To stop drawing, hit the Enter key. 4
Figure 7 - Polar Coordinates Snaps As you draw lines, orange icons may appear (such as the square next to the cursor in Figure 8). These are snap points. Snap points let you set line endpoints based on existing drawing elements. For example, you can set an endpoint for a new line at the endpoint of an old line by moving the cursor to the destination endpoint. Once you get close enough, the endpoint snap will appear. Once it appears, you can click to set the endpoint of the current line at the snap location. To change the type of feature to snap to, hold the Shift key and right-click to get the snap pop-up (Figure 9). Figure 8 - Snap Points 5
Figure 9 - Snap Options From this pop-up, you can set the snap location to several different features including circle centers, tangents and line midpoints. In AutoCAD you can also snap to points not attached to, but based on, existing geometry. For example, if you need to draw a box, you can draw the first two lines using coordinates. To set the third line it would be convenient to just snap to the top of the first line drawn (Sketch 1 in Figure 10). AutoCAD does not pick up this point initially but can be made to recognize the height of the first line by moving the cursor to the endpoint of the first line (Sketch 2) until the endpoint snap shows. When you move the cursor back to the original location a new snap appears that lets you set the height of the third line based on the first line (Sketch 3). You can complete the box by drawing the next line to the endpoint of the first line (AutoCAD will pick this up by default). Figure 10 - AutoSnap 6
Zooming If you need to draw something that would extend past the limits of the current work area or need to zoom in, there are several zooming options. The quickest option is to use the scroll-wheel on your mouse (if present). Rolling the scroll wheel will zoom in and out quickly. If you do not have a scroll wheel, you can use the Navigate pane in the View tab to zoom. To zoom enlarge all currently drawn items to fit the screen, click the Extents button in the Navigate pane. To zoom in or out, click the down arrow next to Extents to get all zoom options (Figure 11). Figure 11 - Zooming Deleting To delete drawing elements, two approaches can be used. The first is to escape out of any current action (Esc key) then select the objects to delete by clicking on them. AutoCAD does not use a Shift or Ctrl click to select multiple objects. Just keep left-clicking on objects to select more of them. To select more than one object, click once to start a selection box, move the cursor (an outline will appear) to the other corner of the selection box and click again. This will select the items in the box. AutoCAD has a useful feature for selecting multiple objects within a box that can be frustrating if you are not aware of it. If you set a point to select a group of objects with a left-click and then drag the cursor to the right to set the next point, you will only select items completely within the boundary of the box (Figure 12). If you set a point on the right first and then drag to the left, you will select all objects that are in the box as well as those that intersect the boundary of the selection box (Figure 13). 7
Figure 12 - Selecting (Left to Right) Figure 13 - Selecting (Right to Left) Once the object(s) to delete are selected, hit the Delete key to delete them. No confirmation is requested but you can undo deleted objects (Ctrl+Z). The other method of deleting objects is to use the eraser. The eraser is in the Modify pane of the Home tab (Figure 14). The icon looks like a pencil eraser. You will find that in most CAD programs, you need to remember several icons for basic operations since text labels might not appear by default. 8
Figure 14 - Erasing Once the eraser has been selected, you can select items in the drawing by left-clicking on them or by using the click-then-drag method mentioned earlier (the left-right feature works as well). Once the objects to delete are selected, hit the Enter key to delete them. Circles and Other Drawing Elements The complete list of drawing elements for 2D sketches can be seen by clicking the down arrow next to Draw in the Draw pane of the Home tab (Figure 15). These elements include circles, polygons and spines. Each item can be drawn using different techniques. Experiment with the various ways of drawing each object. Figure 15 - Drawing Elements Trimming Frequently when making drawings, you need to trim part of a line away or extend a line to meet another one. This can be easily done in AutoCAD using the Trim/Extend feature. This can be accessed using the Trim button in the Modify pane of the Home tab. See Figure 16 for the icon. 9
Figure 16 - Trim A simple use of the Trim feature is shown in Figure 17. In the first sketch, several drawing elements are shown. It is desired to trim away the bottom of the circle. To do this, the Trim feature must first be activated. The objects to use as guides for the trim must then be selected. In this case, the circle and the two vertical lines. The horizontal line has been selected as well. It is not necessary but it is often better to select more items than you need to make sure you have all the relevant geometry. Hit Enter to move to the actual trimming step. You can now click on the objects to trim away or extend. The objects selected in the previous step are used to guide the trimming or extending. Wrapping Up Figure 17 - Trimming Example With these basic operations, you can make simple sketches in AutoCAD. In future tutorials, more advanced features will be detailed. An assignment follows. 10
Assignment Draw the sketch shown in Figure 18. The dimension is included for reference and does not need to be included in your drawing. The upper-left corner uses a circle and a 5-sided polygon. The upper-right uses a circle that has been trimmed (an arc can be used as well). The lower left and right drawings are just lines snapped to various points. The exact dimensions of the drawing do not matter, just the overall look and use of features. Once done, save the file as an AutoCAD 2013 drawing. Submit the.dwg file via Blackboard. The following point breakdown will be used: Outer square (2) Upper-left (2) Upper-right (2) Lower-left (2) Lower-right (2) Figure 18 - Assignment 11