LESSON 1-7

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More Modifying Commands Now it's time to learn a few more commands. Like all of the commands learnt so far, these too will be ones that you will use regularly. Here are the commands that you will be learning in this lesson. Command Keystroke Icon Menu Result Rotate Rotate / RO Modify > Rotate Rotates objects to a certain angle Fillet Fillet / F Modify > Fillet Creates a round corner between two lines Chamfer Chamfer / CHA Modify >Chamfer Creates an angled corner between two lines Array Array / AR Modify > Array Creates a repeating pattern of the selected objects Once again you will recreate a drawing. This one is called Assignment #5. Click here to see the GIF format file. Click here for the DWG file. Follow the steps shown carefully. As these commands require a little more input, make sure that you keep an eye on the command line. You will be asked to provide information throughout the commands. Start up AutoCAD and load the acad.dwt template like you have for the other lessons. Start by drawing a horizontal 10" X 7" border with the bottom left corner at 0,0 Draw a rectangle 1" wide by 3" tall with the bottom left corner at .75,.75 You are now going to rotate this rectangle 90° clockwise. Start the ROTATE command. AutoCAD asks you to select objects. Select all parts of the rectangle and press . Now you must indicate a 'base point'. Think of this as a pivot point around which the rectangle will rotate. In this example, you want to select the bottom right corner (remember to use your Osnap). Once you've selected the base point, the command line shows rotation angle or [Reference]:This means that 'Rotation angle' is the default, so type in the angle you want to rotate the object. Think about how AutoCAD measures angles. Looking at your rectangle and the one on the assignment sheet, you'll see that you want to rotate the rectangle clockwise or: -90 degrees. Enter that number and press .  Command: RO  Current positive angle in UCS: ANGDIR=counterclockwise ANGBASE=0 Select objects:  1 found    Select objects:     Specify base point:     Specify rotation angle or [Reference]: -90            The rectangle is now been rotated -90 degrees from its original     position. Picking different base points will give you different results. Undo the last     command. Try a few different combinations of base points and angles to see     what results you get. When you are done practicing, get the rectangle back     to the position it was at the end of previous step.     Make a COPY of the rectangle 2" above the first     one (remember your relative co-ordinates).      Now you're going to modify the second rectangle so that it has rounded corners.     Start the FILLET     command. Look at the command line. It will look something like this:      Command: F      FILLET    Current settings: Mode = TRIM, Radius = 0.0000    Select first object or     [Undo/Polyline/Radius/Trim/Multiple]:      AutoCAD first shows you what the current fillet radius is (0.0000). This     will be the last value that was used. Once it's changed, it will keep the     new value in memory. The next line shows you what options you have in this     command. Remember that the Capitol     of each option selects that particular option. What you want to do is     change the fillet radius to 3/8" (or .375). To do this you have to     type R     . When you type this AutoCAD will give the chance to enter a     new fillet radius. At this point enter .375 and press .      The fillet radius is now .375 (which is what you want). The default     option is Select     first object. Select the left side of the top rectangle     (yes, the whole rectangle will highlight if you drew it as a rectangle).     AutoCAD now asks you to select second object. Select the top line and     AutoCAD will make a smooth round corner with a radius of .375. AutoCAD     automatically ends the command at this point.      Restart the FILLET command and do     this to the remaining corners so that you have an object similar to the     example.     Copy     the first rectangle to a point 4-1/2" above. Now you will use the     chamfer command to give this rectangle sharp corners.      Start the CHAMFER     command. Look at the command line. It should look like this:      Command: CHA  CHAMFER    (TRIM mode) Current chamfer Dist1 = 0.0000, Dist2 = 0.0000    Select first line or [Polyline/Distance/Angle/Trim/Method]: D     Specify first chamfer distance <0.5000>: .375         Specify second chamfer distance <0.3750>:     Select first line or [Undo/Polyline/Distance/Angle/Trim/mEthod/Multiple]:  This is very similar to the fillet command. You have several options available. Want you want is an even 45 degree angle 3/8" in from the corner. Like the fillet command, you first have to tell AutoCAD what distance you want. To do this, type D to select the Distance option. The command line now looks like this: Specify first chamfer distance <0.5000>: .375 as your first distance.) The command line now asks for the second distance. AutoCAD will automatically change the default of the second distance to match the distance you entered for the first. Specify second chamfer distance <0.3750>: (Press to accept this) You will then be asked to Select first line. The chamfer command works just like the fillet command. Select the line on the left of the top rectangle. (Don't worry if the entire rectangle highlights.) When prompted to Select second line: select the top line. You will now have a perfect sharp corner at a 45 degree angle 3/8" in from the corner. Do this to the rest of the corners. Now look at the assignment sheet and notice the group of six rectangles on the bottom right. You could draw each one individually, but AutoCAD has a command that will allow you to draw one, and it will make the others. Create a rectangle that is 1/2" square with the bottom left corner at 6,1.5 (absolute points). Start the ARRAY command. Look at the dialog box shown below: When confronting a new dialog box, I recommend that you look for what is needed from theTOP DOWN to the bottom. This is a great example. Choose the radio button for "Rectangular Array". This will array the object in a row/column arrangement. Next select the object you want to array, by picking on the button in the top right corner. (Press enter when done) Enter the number of rows (going across the page) and column (running up and down the page). Enter the Row offset. This is this from the bottom left of the original rectangle, to the bottom left of where the first copy will go. Enter the Column offset Pick the Preview button to see the array before committing. If the array is correct (check the sample drawing), press the "Accept" button. If you need to change anything, press the "Modify" button, make your changes in the dialog box and preview again. Now you are going to use the ARRAY (polar) command to create the shape in the top right corner of the assignment. Start by making a CIRCLE with a center point of 7.5,5.5 and a diameter of 1.5 Next make a LINE from the center of the circle going 1" to the right (remember your relative input and Osnaps). Start the ARRAY command. When asked to select objects, pick the line you just drew. Examine the dialog box above. Remember to start from the TOP. In this case, you have to select your objects and select a Center Point for the array. (Select the center of the circle.) Save and print your drawing. So far in seven lessons, you have learned many of the common commands in AutoCAD. It may not seem like a lot, but the idea is to become fluent in them. It should be second nature to run these commands. With practice, you won't the command line to help you along. Think of the first time you drove a car with a manual transmission. After time, it got smoother, didn't it. I can't stress enough how important practice is during these early lessons. Extra Practice: Copy this drawing - extra_009.gif Extra Practice: Copy this drawing - extra_010.gif

LESSON 4-12

LESSON 4-1		AUTOCAD TEMPLATE FILES
LESSON 4-2		USING OSNAPS IN AUTOCAD
LESSON 4-3		LINETYPES AND LINETYPE SCALE
LESSON 4-4		AUTOCAD FILE FORMATS
LESSON 4-5		GRIP EDITING
LESSON 4-6		AUTOCAD'S INQUIRY TOOLS
LESSON 4-7		XREF'S (EXTERNAL REFERENCES)
LESSON 4-8		SYSTEM VARIABLES
LESSON 4-9		TABLES
LESSON 4-10		INTRODUCTION TO SHEET SETS
LESSON 4-11		MODIFYING AND CREATING DIMENSIONS
LESSON 4-11a		TYPES OF DIMENSIONS
LESSON 4-12		INTRODUCTION TO CUSTOMIZING AUTOCAD

Topics covered in this Lesson:

Keyboard Shortcuts | Customizing the Interface

Concept: One of the great things about AutoCAD is that it can be easily customized to suit the individual user. By now, you have seen how you can change the osnaps for example, but you can change a lot more than that. This lesson will introduce you to some of the customization options you have. Keyboard Shortcuts (you will need to have the express tools installed) So far you have been using AutoCAD's default shortcuts. This section will show you how you can create your own to help your productivity. All shortcuts are stored in the acad.pgp file. This file is loaded into AutoCAD every time you start the program. It is now easy to edit thanks to an express tool names ALIASEDIT. Type in this command and you'll see a dialog box pop up. Press the Add button. In this example, I have created a shortcut for MATCHPROP which is usually MA (I find that two keys on opposite sides of the keyboard slow me down). Since N is not used for anything, I find that one letter is more than twice as fast as two. Type in what you see and press OK. Now press Apply so that the changes take effect. You'll see this dialog box warning you that you are about to overwrite your acad.pgp file. Press yes, ONLY if you are sure you did the correct changes. Press Yes and you will see a message pop up that you have saved your changes and that your current AutoCAD session has been updated. That means that you can now use the shortcut you just added. CUSTOMIZING THE INTERFACE Quick Access Toolbar The quick access toolbar is the row of icons at the top of the screen. You'll find Save, Print and other common commands there. One that you won't find is Save as. This is a pet peeve of mine, so I added it. It's easy and you can do it to. Use this method for adding any commands to this toolbar. Navigate the Ribbon to Management > Customization > User Interface. You'll see this dialog box come up. In the top left section, look for the Quick Access Toolbar 1 folder. Then look for the Save as command in the list in the bottom left. Drag the command up to it's desired position on the toolbar. Press Apply. Your toolbar should now look like this. If you have read all the tutorials, you'll know that I don't recommend using icons. Still there are sometimes you may want to. Perhaps the command isn't used much, but you want easy access to it. Perhaps you can't create a shortcut for the command. There could be a few reasons, but here is how to create a new toolbar with the icons you want. With the CUI dialog box open, right click on Toolbars and select New Toolbar. Once you have your toolbar added to the list, drag a command up to it. I've decided that I want to have a toolbar with an Update Dimensions on it to save me some typing. Once you have some commands on your toolbar, press Apply to see your new toolbar. Now you will add icons to your new toolbar. Right-click a toolbar and select Customize again. You'll see all the commands listed. You can now drag and drop an icon from that list to your custom toolbar. For this exercise, look at the list for commands you don't recognize and add them to your toolbar so you can try them out. Right-Click Customization You can also control how your mouse works. By default AutoCAD displays a menu when you right click outside of a command. To do this, type OP for options and go to the user preferences tab. Select the "Right-Click Customization" button. You'll see this dialog box. For example, you should find that using right-click as and 'enter' will speed things up. Unless you frequently use the menus, you should switch to this. These are just a few ways that AutoCAD can be customized. You can create custom hatch patterns and linetypes - even fonts. Other options include programming to automate tedious tasks in VisualLisp, VBA or C++(ARX). As you get more familiar with AutoCAD, look into these options. Ralph Grabowski provides some great tutorials on customization. He also publishes one of the best CAD e-newletters.

LESSON 4-11a

LESSON 4-1		AUTOCAD TEMPLATE FILES
LESSON 4-2		USING OSNAPS IN AUTOCAD
LESSON 4-3		LINETYPES AND LINETYPE SCALE
LESSON 4-4		AUTOCAD FILE FORMATS
LESSON 4-5		GRIP EDITING
LESSON 4-6		AUTOCAD'S INQUIRY TOOLS
LESSON 4-7		XREF'S (EXTERNAL REFERENCES)
LESSON 4-8		SYSTEM VARIABLES
LESSON 4-9		TABLES
LESSON 4-10		INTRODUCTION TO SHEET SETS
LESSON 4-11		MODIFYING AND CREATING DIMENSIONS
LESSON 4-11a		TYPES OF DIMENSIONS
LESSON 4-12		INTRODUCTION TO CUSTOMIZING AUTOCAD

Topics covered in this Lesson:

Dimension Types

Concept: This tutorial will explain the different types of dimensions that commonly used in AutoCAD and help you understand their differences. A good AutoCAD drawing will convey the needed information clearly and accurately. Dimensioning is used to let the drawing reader know what size each length or curve is, without having to open the drawing. If your dimensions are inaccurate, you will not be working in CAD for very long, no matter how accurate your drawing is. Learn when each dimension is needed and how to use it. If you need to modify the appearance of your dimension, please refer to the previous tutorial - 4-11. Dim Type Keystroke Icon Description Linear DIMLINEAR / DIMLIN Dimensions for straight lines either horizontal or vertical to the UCS. Aligned DIMALIGNED / DIMALI Dimensions for straight lines that are angled to the UCS and provides the line's length. Angular DIMANGLUAR / DIMANG Dimensions between 2 points and gives the resulting angle measurement. Arc Length DIMARC Dimensions the length of an arc or arc segment of a polyline. Radius DIMRADIUS / DIMRAD Dimensions the radius of an arc, circle or arc segment of a polyline. Diameter DIMDIAMETER / DIMDIA Dimensions the diameter of an arc, circle or arc segment of a polyline. Center Mark DIMCENTER Places a center mark at the center point of an arc or circle Rotated DIMROTATED - A modifier to a dimension to make it parallel to a selected line. Align DIMSPACE Aligns the selected dimensions to an even spacing. Continue DIMCONTINUE / DIMCONT Continues dimensioning from a base dimension Baseline DIMBASELINE / DIMBASE Continues dimension from a base dimension to give an overall dim. Types of Dimensions in AutoCAD You have most likely already used some of the common dimension types like 'linear' or 'radius'. This section will describe how each one works in mre detail. Linear Dimensions: Linear dimensions are used to create a dimension that measures a line that is either horizontal or perpendicular to the UCS. This is the most commonly used dimension and is very easy to use. Below is a typical linear dimension: It's good practice (thought not always allowed by time) to have your dimensions at a consistent distance from the object. Make sure that it is not to close to overlap the object and not too far to confuse which object you dimensioned. To create a linear dimension, either use the icon or key in DIMLINEAR. Just pick the two endpoints of a line (or any two points) and then place the dimension line where you want it. Very quick, very simple. Command: DIMLINEAR Specify first extension line origin or <select object>:SELECT FIRST POINT Specify second extension line origin:SELECT SECOND POINT Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: SELECT LOCATION OF DIM LINE Dimension text = 5.00 Note that there are some options at the command line: MText / Text You don't need to use these, it doesn't really affect your dimension Angle This will place your text at the angle you specify Horizontal This will create a horizontal dim, but you select this when you place your dimension line. Rarely needed. Vertical This will create a vertical dim, but you select this when you place your dimension line. Rarely needed. Rotated This will create a 'rotated' dimension. This is explained below. You'll also notice on the first prompt, you can <select object>, Press <enter> at this point, and then you can just select the line instead of the two endpoints. This is a lot quicker and more accurate as you don't have to worry about picking the wrong Osnap. Since this is a common command, it is worth creating an alias for it (see next lesson). Aligned Dimensions: The Aligned dimes ion works just like the linear dimension. The big difference is that it works with lines or distances that are not square to the UCS. You can also use this on any 2 points that are also compatible with the linear dimension. It will create a dimension parallel to the angled line. Command: DIMALIGNED Specify first extension line origin or <select object>:SELECT FIRST POINT Specify second extension line origin:SELECT SECOND POINT Specify dimension line location or [Mtext/Text/Angle]: SELECT LOCATION OF DIM LINE Dimension text = 2.00 You'll see that command line prompts are almost the same. Of course, there are no option for horizontal or vertical placement. Also Rotate is missing to avoid confusion and errors. You can also select Angle for your text to match the angle of line (just select 2 points on the line you are dimensioning). Angular Dimensions: Not every dimension gives the reader a length. Sometimes other measurements are need. Angular dimensions will display the angle between two objects. The measurement of the angle is defined by your dimstyle, but degrees is standard. The command works similar to the linear dimensions (see a pattern?). Command: _dimangular Select arc, circle, line, or <specify vertex>: <select first line> Select second line: <select second line> Specify dimension arc The example above shows 3 common uses of this tool. To get the angle on the arc, just select anywhere on it. Getting the outside measurement (225° in this example) is done by following the prompt <select vertex>. Command: DIMANGULAR Select arc, circle, line, or <specify vertex>: Specify angle vertex: <select point A> Specify first angle endpoint: <select point B> Specify second angle endpoint: <select point C> Specify dimension arc line location or [Mtext/Text/Angle/Quadrant]:<place dim> Dimension text = 225 Arc Length: This is a fairly new command in AutoCAD and will not be available on some older versions. This command works quite simply, just start the command and select an arc or arc segment of a polyline. In the example below, I have shown the Angular (180°) dimension with the Arc length so that you can see the difference. Notice the symbol in front of the 3.14. Command: _dimarc Select arc or polyline arc segment: <select the arc> Specify arc length dimension location, or [Mtext/Text/Angle/Partial/Leader]: 1.2 Dimension text = 3.14 Once again, you are offered some options when dimensioning. Mtext/Text/Angle are the same options for text that you saw earlier. Partial will allow you to dimension only part of the arc. This is useful for midpoints or nodes, when the arc is segmented.Leader will draw a leader from the dim text to the arc that it refers to. Radius Dimension: Another common and simple command. DIMRAD will dimension any arc or circle and give you the radius and place a center mark at the center of the selected object. A center mark is a cross the indicates the center point of an arc or circle. Command: _dimradius Select arc or circle: <select object> Dimension text = 0.40 Specify dimension line location or [Mtext/Text/Angle]: <place the dim> Once again, you have some options for the text at the command prompt. Diameter Dimension: The diameter and radius dimensions work the same, but give a different measurement. As a rule, I will use the diameter dim on things like a hole to be drilled or for the dimensions of an overall part and radius for filleted corners, etc. As you see, the diameter and radius dimensions add a center mark (this can be turned off, or changed to a larger line in DDIM). I will usually dimension the circles first so that I can select the center mark and have a small gap (it looks cleaner). Command: _dimdiameter Select arc or circle: <select the object> Dimension text = 1.00 Specify dimension line location or [Mtext/Text/Angle]: <place the dim> In the example image above, you can see that even a very simple drawing can have enough dimensions to clutter things up. Make sure that you have enough dimensions and don't duplicate or miss any. Make sure that they can be read from one or two angles when printed (usually from the bottom right corner). Center Mark:By now you should be getting the hang of how this works. The center mark command adds a center mark to a circle or arc. How it is displayed is set in the DDIM dialog box under the "Symbols and Arrows" tab. If you select "None" you will not be able to place a center mark using this command. The icon for center marks is in the sub menu on the dimension panel. Sometimes you might use both in the drawing. Below. on the left, I used the center mark that was made with the diameter dimension, then I dimensioned from it. On the right, I used a Line center mark and extended one of the lines to the other side to indicate the the holes are aligned. Then I double-clicked on the diameter text and added a suffix to indicate that both holes are the same size. But when you do this, any of the center marks made by the diameter or radius dimensions will change to the new style that you selected. It's best to start with one style and leave it. Rotated Dimensions: A rotated dimension is not a dimension that was rotated using the rotate command. Instead it allows you to create a linear dimension to two points that are not in a straight line. Look at the image below and see the difference between an aligned dimension and a rotated one. First, look the dimension on the far right. See how it gives a true overall size of 10 units? On the right, the aligned dimension is not the overall size due to the 94° angle in the bottom left corner. Also in the top right, notice the rotated dimension with 2.00 units. I need to rotate it as the 2 points that I selected were not on the same axis. A little confusing at first, but try it a few times. Command: dimlin DIMLINEAR Specify first extension line origin or <select object>: <first endpoint> Specify second extension line origin: <first endpoint> Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: R <enter> Specify angle of dimension line <0>: <select first point on axis> Specify second point: <select second point on axis> Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: <place dim> Dimension text = 2.00 When it comes to selecting points on the axis, pick the common parallel line (in this example, I click 2 points on the 10 unit dimension. You can also created a rotated dim by using the DIMROTATED command. In this case, you select the angle first. Align Dimensions: Sometimes you might have a bunch of dimensions in one area and want to space them evenly. The easy way to do this is to place them quickly, then use the Align Dimension command, DIMSPACE. Look at the image below with the random spacing. Then mouse over it to see how this commands gives them even spacing. Draw a similar shape and try this. Place your dims, but allow for enough room to fit them all (just don't worry about the spacing). Then start the DIMSPACE command. Command: DIMSPACE Select base dimension: <I selected the 2.00 dim in this example> Select dimensions to space: Specify opposite corner: 3 found <select the others> Select dimensions to space: <enter> Enter value or [Auto] <Auto>: <enter> Fast and easy. You have the option at the end to enter a distance between each dim, but Auto should work in most cases. Continue Dimensions: Another shortcut is to use continued dimensions. With this command, you can select a 'base' dimension and then have AutoCAD help by continuing the command so that you can just click and endpoint and continue to the next, click an endpoint, etc. Have a look at the drawing below: When you have a series of dimensions all in one plane like this, just create the first one with DIMLIN and then use the DIMCONTcommand to create the rest of them. In this example, I created the dim on the left first. Tip: When using this command or the Baseline dimensions, select your points for the base dim in the direction that the others will follow. In the example above, since I selected the base dim on the left, I had to first pick the left point and then the right point. This sets the direction for the others to follow. With the the DIMCONT command running, just select the next points to the right (A and the B in this example). After doing this, the next time you start the DIMCONT command, it will return to this point and continue on. Try this out in your own drawing with a simple shape like the one above. Baseline Dimensions This command is very similar in function to the continue command, but instead provides an overall dimension based upon the first point you select in your first (base) linear dimension. Once again, I first needed to create a base dimension with the DIMLIN command. I again used the dim on the left. Then I started theDIMBASE command and selected points A and B. Once again, try it out and see how this works. See what happens when you create your base dim from right to left. Summary: You have a lot of tools at your disposal when it comes to dimensions. The trick is to know when to use each one. It's also extremely important that you are accurate. Clicking on another dimension instead of a line's endpoint can be a huge mistake - especially in mechanical drafting where tolerances are small. Review your dimensions before sending a drawing off to someone else, or printing it- then check it again. Check for overlaps or other confusing areas. The commands themselves are easy to use, but accuracy is critical.

LESSON 4-11

LESSON 4-1		AUTOCAD TEMPLATE FILES
LESSON 4-2		USING OSNAPS IN AUTOCAD
LESSON 4-3		LINETYPES AND LINETYPE SCALE
LESSON 4-4		AUTOCAD FILE FORMATS
LESSON 4-5		GRIP EDITING
LESSON 4-6		AUTOCAD'S INQUIRY TOOLS
LESSON 4-7		XREF'S (EXTERNAL REFERENCES)
LESSON 4-8		SYSTEM VARIABLES
LESSON 4-9		TABLES
LESSON 4-10		INTRODUCTION TO SHEET SETS
LESSON 4-11		MODIFYING AND CREATING DIMENSIONS
LESSON 4-11a		TYPES OF DIMENSIONS
LESSON 4-12		INTRODUCTION TO CUSTOMIZING AUTOCAD

Topics covered in this Lesson:

Dimension Styles

Concept: A drawing needs to contain certain information. Most drawings will show you what the object is (as clearly as possible) but won't tell you everything unless you dimension it. Would you agree to buy a house just by looking at the floor plan if it wasn't dimensioned? Would manufacturers know how to build your product if you didn't dimension it? You can see how important it is that a drawing used to convey information must have clear, accurate dimensions. In previous lessons, you have done some dimensioning (first was Lesson 1-8). To continue with this lesson, you should at least have a good concept of basic dimensioning. There are many ways to dimension a drawing, each drafting discipline has it own set of "rules". For example, a drawing of a gear would use a different style of dimensioning than that of a subdivision. My background is in mechanical drafting, so I use that discipline as an example of how to work with setting your dimensions to work with your drawing. Below is an example of how a drawing can be dimensioned: As you can see, on a simple drawing like this one, only 8 dimensions are needed to convey all the information about the size and shape of the object. With a little more information you can have everything you need to build it. This is the default style you get with the AutoCAD template. Below shows the same drawing, but with added tolerances and note about what the object is made out of. The changes in the dimensions above were done easily using the DDIM command. This command opens a dialog box for changing the parameters of your dimensions. In this example, the text style was also changed. The great thing about AutoCAD is that it is very versatile. In the case of dimensions, you can modify any component that is part of it. Below are the names of various parts of a dimension: Also, you can modify the dimension text dramatically, here are some examples: : The Dimension Style Manager  So now that you have seen what can do - how do you do it? All options are available in the DDIM (Dimension Style Manager) dialog box. On the left is current style for working with (highlighted in blue). In this lesson, you will create a new Dimension Style and use it in a drawing. From there, you should try different styles and get familiar with the options. Most companies these days will have a standard style (or set of styles) to use on drawings, but this is a very important tool to know if you want to turn out professional looking drawings. Start but invoking the DDIM command and press the NEW button to open the small dialog for entering the name of the style you are creating. In this example I used the name "DIMSTYLE 1". Make sure that "Start with" has "Standard" as its setting. Press the Continue Button when everything is set. This will open the dialog box for settings, so just press OK to close it for now. Back at the "Dimension Style Manager" dialog box, you will see that the new style you created is listed at the top (left side). To modify it, select the name, then press the modify button. The dialog box opens and click on the second tab (Symbols and Arrows). As a general rule, I recommend not change much on this tab - especially when you're learning. Set as defaults, the dimensions are sized proportionately, if you change the setting on one parameter, your dimension can look 'off-balance'. For example, you could end up with huge arrows and small text. For the purposes of this lesson, the only thing that will change on this tab is the arrowheads. Select something other than the standard. You'll also see that you can set the colors, but just like regular objects, it's best to leave them set to "Bylayer" - and make sure you have a separate layer for all dimensions. Go to the third tab (Text). Start up the Text Styles dialog box by pressing the button with the ... next to the text name. Create a new textstyle using RomanS and a width of 0.8 and call it "DIMTEXT". (For more info, see Lesson 1-8.) Close the Text Styles dialog box. Select DIMTEXT as your text for dimensions as shown. The great thing about this dialog box is that it shows you a preview of what your changes will do the final dimension in the top right window. In the bottom right, select ISO as the Text Alignment option. Try some other changes to see their effects in the preview, then end with the settings as shown below: So far you haven't changed much, but you've seen the options available in just 2 tabs. Click on the next tab to continue. As a rule, I leave this tab alone. AutoCAD does a good job of placing and fitting dimension where I want them. If I don't agree, I usually just use grips to edit the placement. Click on the next tab (Primary Units) to continue. In the Primary Units, you find some of the more common parameters that need to be changed. Precision is very important. First off, you usually don't need to show 4 decimal places. If you do show 4 decimals places and send your drawing off to the machinist, you are asking him to manufacture the part to within 1/10000 of a unit - which can be a very expensive mistake. 3 Decimal places is usually enough - or less for rougher jobs. Also, I have added a couple of other changes; adding trailing zeros and a suffix denoting the units. Note how angular dimensions have a separate section - make sure you don't neglect them. Make the changes you see above and check the preview after each change. In this tab, you can also set the overall scale of your dimensions. This can also be done using the DIMSCALE command. Using the DIMSCALE setting If you have dimensions on your drawing that are either too large, or too small, use the DIMSCALE setting to make scale them. If your DIMSCALE is currently set to "1", you can make the dimensions larger by entering larger numbers. For example, enter 12 will make your dims 12 times large than they were at "1". This does not enlarge the value of the dimension, just the size of the dimension. To make your dimensions smaller, you can also enter fractions or decimal numbers like ".5". These numbers are all based from the standard sizes set in your DDIM dialog box. For example, if you enter "12" to make them larger, entering 1/2 later will not make them scale to "6". After changing the DIMSCALE, all new dimensions will use this scale. Using DIMSCALE is important to make sure that people can easily read your drawings. Set your DIMSCALE before adding all of your dimensions. After changing the scale, you will not see a change. You will need to update the dimensions. Follow these steps: Command: DIMSCALE Enter new value for DIMSCALE <1.0000>: 12 Command: DIM Dim: UPDATE Select objects: ALL 2 found Select objects: <ENTER> Press <ESC> twice to exit the Dim prompt. The next tab (alternate units) is used if you want to display two different units in your dimension. For example, you can draw your drawing in imperial inches, then dimension with inches as your primary units and add the alternate units behind. Skip this tab for now and go on to the last tab (Tolerances). In this example, you will set the tolerances to be +/- .05 units and display them at 80% of the primary units. Sound easy? It is. Look at the image below to see how this is done. Once again - preview shows you how it will turn out. Click OK to close the dialog box. At the original Dimension Style Manger, press the name of your new style, then click the "Make Current" button. Close the dialog box to go back to your workspace. Draw the wedge shape at the top of the less and dimension it using your new Dimension Style. It should look something like this: Now you have the basic understanding of how dimensions work, you can experiment and work with other styles. Here are some common rules about dimensioning: Keep them on a separate layer. Dimension towards the end of your project or you could be moving them as you add more objects. Use your Osnaps and confirm what you are snapping to. Assign them a unique colour in the drawing, and use that colour in all of your drawings to make it easier to identify dimensions (especially when zoomed in close) After you create your first dimension, AutoCAD creates a new layer called "DEFPOINTS". This is used only for the small points you see at the end of an extension line. This layer will not print - so be sure not to draw on it. Keep even spacing between you dimensions and between your dimension and your object lines. Use DDE while placing dims. Try not over lap lines (either object or dimension). Use enough dimensions to make sure that all measurements are there - one dimension left out can hold up a project. Try to keep dimensions outside of the objects you are dimensioning. For clarity, don't over-dimension. If you need to override one dimension (perhaps a unique suffix), you can change it in the properties (select > right click > properties) Dimensioning in Layouts If you are familiar with Layouts (or Paper Space) as shown in Lesson 2-4, you can continue with this lesson which will explain dimensioning in Layouts. Using the same wedge shape from above, delete your dimensions and then scale the wedge up by 24X. Go into your Layout and use a zoom factor factor of 1/12xp for your viewport. Start dimensioning your lines. AutoCAD now does a great job of dimensioning in Layouts. It will recognize the scale of the viewport and find the correct size of the object you are dimensioning. I recommend doing all of your dimensioning in you Layouts. There are a few reasons for this: It leaves your model space free of dimensions For 3D objects, this system is MUCH easier. You only need one size of dimensions for full view and details. You can add your title block, notes and dimensions in one area. I hope that this lesson has given you the ability to create professional, accurate dimensions. Like everything else in AutoCAD, practice make perfect. For more practice, create a simple floor plan and create a dimension style using Architectural units and 'ticks' instead of arrows. Use a precision of 1/2". Here's a very simple Architectural drawing using this style.