Unit 3.11 Introduction to Absolute & Polar Coordinates in AutoCAD Ardrey Kell High School Charlotte, NC Date: 11/18/13 (Revision II)

Transcription

1 Unit 3.11 Introduction to Absolute & Polar Coordinates in AutoCAD Ardrey Kell High School Charlotte, NC Date: 11/18/13 (Revision II)

2 Ardrey Kell High School Charlotte, NC Drafting 1 Computer Aided Design Skills Review - Absolute Coordinates Absolute Coordinates: Used with CAD systems (Not used much anymore) as a way to input lines and points using coordinates entered into the system with the keyboard. All points, line directions and lengths are drawn relative to the origin (0,0) (Hint: Remember Absolute Zero ) Open the following file: Absolute Coordinates 1.dwg Steps to create an L shaped block using absolute coordinate keyboard entry 1. Type L (Enter) 2. Type 0,0 (Enter) 3. Type 6,0 (Enter) 4. Type 6,3 (Enter) 5. Type 3,3 (Enter) 6. Type 3,6 (Enter) 7. Type 0,6 (Enter) 8. Type 0,0 (Enter)(Enter) These commands when typed correctly will produce a 6 x 6 square with the upper right quadrant removed to produce an L shaped object as shown below.

3 You will now add a smaller L inside the existing object using absolute coordinate input 1. Type L (Enter) 2. Type 1,1 (Enter) 3. Type 5,1 (Enter) 4. Type 5,2 (Enter) 5. Type 2,2 (Enter) 6. Type 2,5 (Enter) 7. Type 1,5 (Enter) 8. Type 1,1 (Enter) (Enter) You should now have a smaller L inside the first object you drew as shown below.

4 You will now use the Hatch command to add crosshatching to the area inside the small L you just drew. 1. Type H (Enter) The window below shows the Hatch window as it should appear on your screen. 2. Set the values in each box as shown by the callouts, then click on the (Add Pick Points button) 0.00 Add Pick Points 4.00 Figure 1 3. Left click the mouse in the location indicated in the figure below. (Inside the small L ) Left Click Here 4. After left clicking the mouse, right click the mouse and a small menu will appear. 5. Select Enter from the menu

5 6. Select OK at the bottom of the Hatch dialogue window that pops up, then your drawing should look like the picture below. Now you will use Absolute Coordinates to create a 3D drawing. In the following activity, absolute coordinates will be entered that will create a 6 x 6 wireframe isometric cube. (This will be a 3D drawing) Open the following drawing: Absolute Coordinates 2.dwg 1. Enter the following coordinates: a. L (Enter) b. 0,0,0 (Enter) c. 6,0,0 (Enter) d. 6,6,0 (Enter) e. 0,6,0 (Enter) f. 0,0,0 (Enter)(Enter) At this point you should have a 6 x 6 square drawn in the upper right quadrant of the drawing grid. With this square drawn, you are now going to add a 6 depth line (Z Axis) above each corner of the square in order to create the edges of a 6 cube.

6 2. Select the lower right corner of the viewcube to rotate the drawing so that it will appear as an isometric square as shown below: Click This Corner 3. Now enter the following coordinates and notice that a square is being drawn offset 6 above the existing square that you just drew. a. Type L (Enter) b. 0,0,6 (Enter) c. 6,0,6 (Enter) d. 6,6,6 (Enter) e. 0,6,6 (Enter) f. 0,0,6 (Enter) (Enter)

7 At this point you should have two squares drawn as shown below. One square is drawn 6 above another 6 square. Now you will add the edges of the cube by adding lines that connect the corners of the 2 squares. These lines illustrate the Z (depth) axis. 1. Enter the following coordinates: a. Type L (Enter) b. 0,0,0 (Enter) c. 0,0,6 (Enter) (Enter) 2. Enter the following coordinates: a. Type L (Enter) b. 6,0,0 (Enter) c. 6,0,6 (Enter) (Enter) 3. Enter the following coordinates: a. Type L (Enter) b. 6,6,0 (Enter) c. 6,6,6 (Enter) (Enter) 4. Enter the following coordinates: a. Type L (Enter) b. 0,6,0 (Enter) c. 0,6,6 (Enter) (Enter)

8 You should now have a 6 x 6 cube exactly like the drawing below. Each of the entries numbered 1-4 above added a corner line to the cube. When using absolute coordinates it is vitally important that you recognize where the object is located in space, and how it relates to the origin(0,0,0). Note, negative Z axis coordinates input into CAD cause the lines to project away from the viewer, whereas positive Z axis coordinates project the lines from the origin towards the operator. The following chart indicates the direction numbers will be drawn when a positive or negative number is input. Number AXIS X Y Z Positive Number From origin to Right From origin Up From the origin coming up towards you Negative Number From origin to Left From Origin Down From the going away away from you

9 Now open the following drawing file: Absolute Coordinates 3 Your assignment now is to create a 4 x 4 cube in the top left quadrant of the Absolute Coordinates 3 drawing. Before beginning work in AutoCAD, complete the charts below, then check your work by entering the coordinates from the charts into AutoCAD. Base Square Coordinates From Point To Point From Point Coordinates To Point Coordinates X Y Z X Y Z Line 1 Origin A Line 2 A B Line 3 B C Line 4 C Origin Top Square Coordinates From Point To Point From Point Coordinates To Point Coordinates X Y Z X Y Z Line 1 Origin A Line 2 A B Line 3 B C Line 4 C Origin Coordinates From Point Line 1 Origin Origin Bottom Top Line 2 A (Bottom) A (Top) Line 3 B (Bottom) B (Top) Line 4 C (Bottom) C (Top) Side Edges Showing Depth To Point From Point Coordinates To Point Coordinates X Y Z X Y Z 0 0 0

10 Upon Completion, the 4 cube drawing should look like the drawing below: STOP HERE This ends the lesson on Absolute Coordinates

11 Ardrey Kell High School Charlotte, NC Drafting 1 Computer Aided Design Skills Review - Polar Coordinates Polar Coordinates: Used with CAD systems as a way to input lines and points using coordinates entered using the keyboard. Polar Coordinates are located in relation to a previously drawn point. Line commands are entered as follows: To draw a line 8 units long at an angle of 45 degrees the following should be To draw a line 10 units long at an angle of 90 degrees the following should be In AutoCAD, angles are measured as shown on the compass rose below: Angles drawn in a clockwise direction require negative numbers to be entered. Angles drawn in a Counter clockwise direction require that positive numbers be entered Open the drawing: Polar Coordinates 1 Use the following steps to create an object using polar coordinates and keyboard entry. 1. Type L (Enter) 2. Type 0,0 (Enter) 3. (Enter) 4. (Enter) 5. (Enter) 6. (Enter) 7. (Enter) 8. (Enter) 9. (Enter) 10. Type C (Enter) ( C - Enter is used to complete the last side of a closed polygon ).

12 The item you just drew should look like the drawing below: The object created should look like this. Now, complete the chart below by adding the coordinates necessary to create an identical shape offset 1 towards the center of the given object. Upon completion of the chart, input your coordinates into your AutoCAD drawing and see if your drawing matches the drawing below. The object you are to create should look like this Type L (Enter) 1,1,0 (Enter) Drawing Coordinates Length Direction Angle