LESSON 1-8

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LAYERS AND DIMENSIONING Now that you've learned a lot of the drawing and modifying commands, it's time to go to the next level. This lesson will introduce you to text, dimensioning and the concept of layers. What you will do is take one of your previous assignments, save it to a new name and then add text and dimensions to it. These are the commands you'll be learning. Command Keystroke Icon Menu Result Layer Layer / LA Format > Layer Starts the Layer and Linetype property dialog box Text Text No Icon Draw > Single Line Text Creates a single line of text Dimension Dim Many Dimension > (pick one) Dimensions previously drawn objects Scale Scale / SC Modify > Scale Proportionately resizes (or scales) objects Begin by opening up Assignment #5 from your CAD folder. Using the SAVE AS option, immediately save it under the name Assign6.dwg The first thing you want to do is create three layers. Layers are used to organize drawings. Imagine a large project for a high-rise tower. The designers would create layers for the electrical, plumbing, landscape and more. It is necessary to control the drawing and turn some layers off and view only the ones you want. This is one reason why layers are needed. But if you were to use AutoCAD professionally, every drawing you dealt with would have layers. You will be creating a layer for the dimensions, one for the lines (objects that were drawn) and another for the text. Start the LAYER command (LA). This will bring up the Layer Properties Manager (shown below). We'll cover the things that are used most often in this lesson. Looking at the Dialog Box, you will see a lot of information. Notice the button beside Make Current on it. Below it is the name of the current layer you are drawing on. The main window gives you information about each particular layer. At this point, you want to be concerned with the 'Name', 'On' (light bulb) and 'Color' (colored square) columns as well as the 'New' button. Now you have the dialog box on your screen, click the 'New' button. This will create a new layer and give you an opportunity to name it. Name this layer TEXT. Click on the small box towards the right and select yellow for the color. Create another layer and call this one DIM(for dimensions), and make its color red. Finally, create a third layer and call it OBJECT and make its color green. You have just created three new layers in your drawing. Highlight the TEXT layer and then press the 'Make Current' button. This makes the TEXT layer current and anything you draw will be placed on that layer. Your Dialog box should look like the one above. If it does, press OK to close the dialog box. More about Layers In the Layer Properties Manager, you will notice that each layer can have a number of specific properties. · Status: Displays the current state of the layer. In this example, the green check means that Objects is the current layer. · Name: The name of the layer. Give layers understandable names. · On: If a layer is 'On' it means that it is visible (but objects can still be erased when the 'Select > All option is used). · Freeze: A layer is not visible and cannot be deleted. · Lock: Layer is visible, but cannot be modified. · Color: A specific color for everything on that layer. · Linetype: A specific linetype (hidden, center, etc) for the layer. · Lineweight: The visible width of the objects on that layer. · Plot: A defined color for the plotter to use on that layer. · Plot (yes, two colomns use the same name: Switch on or off if that layer is plotted. · Description: A user-defined description for the layer. ADDING TEXT TEXT is your current drawing layer now, so what you will be doing is creating some text now. Type in TEXT on the command line. Look at the command line. Command: text Justify/Style/: The first thing AutoCAD wants is a starting point for the text. Type: 0,0 to place it at the bottom left corner of your drawing. Notice that there are other options you could make, but ignore them for now. Height <0.2000>: Next, AutoCAD wants to know how tall you want your letters to be. For this assignment, you want them to be 1/4" tall. Type in .25 at the Height prompt. Rotation angle <0>: One more thing before you start typing in text, tell AutoCAD if you want to have your text rotated. Not this time, so press to accept the default of 0 degrees. Text: (YOUR NAME - ASSIGNMENT #6) Finally you can type in what you want to put on the drawing. At the prompt, type your NAMEand ASSIGNMENT #6 then press . You will see that AutoCAD has placed your name in the bottom left corner at 1/4" high and in yellow on the 'Text' layer. You don't really want your name jammed into the corner like that so move it up and over 1/8" (Remember your MOVE command and relative points : @.125,.125) Now it's time to start dimensioning your drawing. Bring up the Layer dialog box and make DIMyour current layer. This is one time when I recommend to use the icons. Dimensioning is A LOT easier this way. If you don't see your dimensioning toolbar on the screen, right click on one of your toolbar icons and check the Dimension checkbox. You'll see the toolbar appear. Close the Toolbars dialog box. There are several different types of dimensions, here are the ones you'll be using in this lesson (Each of the dimensioning icons gives you a quick clue as to which type of dimension it will create.) The image below shows you the standard dimensioning icons. This list below shows you which dimension types you will use in this lesson (Place your mouse on the toolbar icons to see what they represent. Here are the ones you'll be using in this lesson. Linear dimensions are used for dimensioning either horizontal or vertical distances. Aligned dimensions will measure the actual length of an angled line. Radius dimensions will give you the radius of either arcs or circles. Diameter dimensions are used on circles. Angular dimensions will measure the angle between two lines that you pick. Baseline dimensions are a special type that will automatically stack dimensions along one plane as you pick points. The type of dimension you pick will depend entirely upon what information you want to convey to the person reading the drawing. Look at the sample drawing and pick out the different types of dimensions and where they are used. We'll start with the most common (and easiest): Linear Dimensions. You'll use this type to add dimensions to the rectangle in the bottom left of your drawing. Pick on the icon and then look at the command line. Command: _dimlinear Specify first extension line origin or :     It asks for either the origin of the first dimension line (a starting     point) or you can press  to select a particular line. Turn     your OSNAPS on to endpoint only. Pick the top left corner of     the rectangle. AutoCAD then asks for the second extension line origin. Pick     the top right corner. You'll then see the dimension appear and AutoCAD asks     for the Dimension line location. Pick somewhere just above the line     where you think it fits well.     AutoCAD then shows you the length that it found to be the length of the     line you just dimensioned. The following lines show what you should have     seen on your command line:        Specify second extension line origin:  Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]:  Dimension text = 3.000 Now dimension the line on the left side using the same method. Now you want to dimension the radius of the fillet on the object above the first box. Pick the icon for radius dimension. AutoCAD asks you to select an arc or circle. Pick the arc on the top left corner. Again AutoCAD then wants you to pick the dimension line location. Pick anywhere outside the arc where the dimension fits well. Looking at the top left object on the sample sheet, notice that there are a few ways to dimension the corners. Start on the bottom left. Pick the Linear Dimension icon. Instead of picking the two endpoints, press and AutoCAD will ask you to select the object you want to dimension. Pick on the angled line in the bottom left corner. As you move your cursor around, you'll see that you could place it either to the left or below the line. Choose one or the other and place your dimension. Repeat these steps to add the other dimension. At the top left, you want to add an Aligned dimension. Pick the icon for this. As with the linear dimensions, you can either pick the endpoints or press to choose and object. When you're asked to place the dimension, you'll see that you can only move parallel to the line that you picked. Place the dimension line somewhere outside the object. Now you're going to dimension the angle on the bottom right corner of the top box. Pick the Angular dimension icon. Pick the bottom line and then the angled line in the bottom right corner. Place the dimension so that it looks like the one in the sample. Now its time to dimension the circle. Pick the icon for the Diameter dimension. AutoCAD then wants you to select the arc or circle. Pick anywhere on the circle. Then you have to place the dimension line somewhere. Pick a good spot for it. Dimension the 1" line in the circle as shown using a linear dimension. Dimension the top left box of the array as shown using Linear dimensions. Dimension the space (0.75) between the two rows by picking the endpoints of the lines. Dimension the space (0.75) between the columns as shown. Now for the tricky part. You want to add baseline dimensions to the column distance dimension you just created. Pick the icon for the baseline dimensions. Look at the command line: You may be asked to select the base dimension. If so, pick on the 0.75 dimension for the column. Then you're asked to Specify a second extension line origin. Pick whereP1 shows you on the sample drawing. AutoCAD then will get you to keep repeating this process until you press to end the command. Pick near P2 to continue, then press. This is what your command line should have looked like: Command: _dimbaseline Select base dimension: Specify a second extension line origin or (Undo/):    Dimension text = 1.50    Specify a second extension line origin or (Undo/):  Dimension text = 2.00 Specify a second extension line origin or (Undo/):      Your drawing should now look similar to the sample drawing. Check to see     if you missed any dimensions.      Now you have dimensioned the drawing, save it and print     it.     Next you want to copy everything over 12" to the right. Start the COPY     command, and when asked to select objects, type ALL .     Then copy it all 12" to the right.     What you want to do next is scale the copy of everything to double its     existing size. Start the SCALE command. When asked to select     objects, draw a window around the new set of objects and press     . When asked for a base point, pick the bottom left corner of     the border. Enter 2 for the scale factor. Your command line should     look like this:     Command: sc    SCALE    Select objects: Other corner: 38 found    Select objects:    Base point:/Reference: 2      Perform a Zoom Extents (type Z  E ) at the     command line. Now that everything is twice as large, Zoom in on your dimensions     and you'll see that they have automatically adjusted to the new sizes! This     is called associative dimensioning.     There are many different parameters you can change to get just the right     look for your dimensions and text (use the DDIM command). This is     will not be covered in this course.     For practice, you can try dimensioning some of your other assignments.     Even if your drawing is 100% accurate, it is still only as good as the     dimensions. Some common mistakes when dimensioning are:     ·             Not using your Osnaps.     If you don't get the exact endpoint of a line, then your dimension is     wrong.     ·             Snapping to the wrong     point. In detailed drawings, this can be easy to do if you aren't paying attention.     ·             Incomplete dimensions.     If you miss one or two dimensions, you can delay the project while these     numbers are located, new drawings made, delivered, etc..     ·             Confusing dimensions.     Make sure that your dimensions don't overlap, or aren't too close, or otherwise     unclear.      For dimensioning practice, dimension the extra lessons from the previous     lessons. Also put objects and dimensions on separate layers.           Extra_001.gif Extra_002.gif Extra_003.gif Extra_004.gif Extra_005.gif Extra_006.gif Extra_007.gif Extra_008.gif Extra_009.gif Extra_010.gif