Entering Survey Data using AutoCADby R.K.McSwainIntroductionThese techniques apply to basic CAD programs such as AutoCAD, IntelliCAD, etc. If you have a civil/survey program or add-on, such as Land Desktop, SurvCADD, Eagle Point, etc., then there are built-in tools for entering lines and curves.Lines and tangent curvesLet's say you have a paper plot or a legal description of a closed boundary. Let's work our way around it. Below is an example of what you might have. Start with a line segment if there is one. Let's start in the lower left (or most southwesterly) corner and work clockwise for this example.

For each line segment, a bearing and distance is given.Start the ._LINE command and pick a starting point. If you have XY or Northing and Easting coordinates, you can enter them, otherwise just pick any point in the drawing. Then at the next prompt enter@107.65 right click > properties)Dimensioning in LayoutsIf you are familiar with Layouts (or Paper Space) as shown inLesson 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.

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 TypeKeystrokeIconDescription

LinearDIMLINEAR / DIMLINDimensions for straight lines either horizontal or vertical to the UCS.

AlignedDIMALIGNED / DIMALIDimensions for straight lines that are angled to the UCS and provides the line's length.

AngularDIMANGLUAR / DIMANGDimensions between 2 points and gives the resulting angle measurement.

Arc LengthDIMARCDimensions the length of an arc or arc segment of a polyline.

RadiusDIMRADIUS / DIMRADDimensions the radius of an arc, circle or arc segment of a polyline.

DiameterDIMDIAMETER / DIMDIADimensions the diameter of an arc, circle or arc segment of a polyline.

Center MarkDIMCENTERPlaces a center mark at the center point of an arc or circle

RotatedDIMROTATED-A modifier to a dimension to make it parallel to a selected line.

AlignDIMSPACEAligns the selected dimensions to an even spacing.

ContinueDIMCONTINUE / DIMCONTContinues dimensioning from a base dimension

BaselineDIMBASELINE / DIMBASEContinues dimension from a base dimension to give an overall dim.

Types of Dimensions in AutoCADYou 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 inDIMLINEAR. 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:DIMLINEARSpecify first extension line origin or :SELECT FIRST POINTSpecify second extension line origin:SELECT SECOND POINTSpecify dimension line location or[Mtext/Text/Angle/Horizontal/Vertical/Rotated]:SELECT LOCATION OF DIM LINEDimension text = 5.00Note that there are some options at the command line:MText / TextYou don't need to use these, it doesn't really affect your dimension

AngleThis will place your text at the angle you specify

HorizontalThis will create a horizontal dim, but you select this when you place your dimension line. Rarely needed.

VerticalThis will create a vertical dim, but you select this when you place your dimension line. Rarely needed.

RotatedThis will create a 'rotated' dimension. This is explainedbelow.

You'll also notice on the first prompt, you can, Pressat 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 (seenextlesson).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:DIMALIGNEDSpecify first extension line origin or :SELECT FIRST POINTSpecify second extension line origin:SELECT SECOND POINTSpecify dimension line location or[Mtext/Text/Angle]:SELECT LOCATION OF DIM LINEDimension text = 2.00You'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: _dimangularSelect arc, circle, line, or :Select second line:Specify dimension arcThe 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.Command: DIMANGULARSelect arc, circle, line, or :Specify angle vertex:Specify first angle endpoint:Specify second angle endpoint:Specify dimension arc line location or [Mtext/Text/Angle/Quadrant]: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: _dimarcSelect arc or polyline arc segment:Specify arc length dimension location, or [Mtext/Text/Angle/Partial/Leader]: 1.2Dimension text = 3.14Once again, you are offered some options when dimensioning.Mtext/Text/Angleare the same options for text that you saw earlier.Partialwill allow you to dimension only part of the arc. This is useful for midpoints or nodes, when the arc is segmented.Leaderwill draw a leader from the dim text to the arc that it refers to.

Radius Dimension:Another common and simple command.DIMRADwill 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: _dimradiusSelect arc or circle:Dimension text = 0.40Specify dimension line location or [Mtext/Text/Angle]: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 inDDIM). I will usually dimension the circles first so that I can select the center mark and have a small gap (it looks cleaner).Command: _dimdiameterSelect arc or circle:Dimension text = 1.00Specify dimension line location or [Mtext/Text/Angle]: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 theDDIMdialog 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:dimlinDIMLINEARSpecify first extension line origin or :Specify second extension line origin:Specify dimension line location or[Mtext/Text/Angle/Horizontal/Vertical/Rotated]:R Specify angle of dimension line :Specify second point:Specify dimension line location or[Mtext/Text/Angle/Horizontal/Vertical/Rotated]:Dimension text = 2.00When 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 theDIMROTATEDcommand. 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 theDIMSPACEcommand.Command:DIMSPACESelect base dimension:Select dimensions to space:Specify opposite corner: 3 foundSelect dimensions to space:Enter value or [Auto] :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 theDIMCONTcommand 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 theDIMCONTcommand running, just select the next points to the right (A and the B in this example). After doing this, the next time you start theDIMCONTcommand, 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 DimensionsThis 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 theDIMLINcommand. I again used the dim on the left. Then I started theDIMBASEcommand 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.