Las Vegas, Nevada November 27-30, 2001

Transcription

1 Las Vegas, Nevada November 27-30, 2001 Speaker Name: Phil Leverault Course Title: Conquering Dimensions Course ID: Course Outline: Factors to Consider for Dimension Styles Discipline Mechanical Dimensioning Methodology Normal English or Metric Ordinate Tolerancing Methodology Basic Limits Variance Architectural Styles Oblique Slashes Aligned with Dimension Lines Above Dimension Lines Angular Dimension with Arrows Leaders with Dots or Arrows Civil Base Unit 1 ft Scale due to Decimal feet and decimal parts of a foot Structural Base Unit 1 in. Why Dimension Styles Dimension Styles hold the description of group of dimension variables Consistency with ease Company Standards Allows for minor adjustments through the use of children Allow for very fine adjustments with Dimoverrides 1

2 What NOT to put in a Dimension Style DO NOT put fine tuning items into a DimStyle Will end up with 100 s of DimStyles Let the fine tuning methods take care of these situations Examples Tolerance Values 1000 s of combinations Where do you place DimStyles How to Dimension Create a Dimension Style Mechanical English Mechanical English Basic Mechanical English Limits Mechanical English Variance How to Use Dimension Styles Dimensioning Methodology Set Current DimStyle Most predominant in drawing Toolbar Running OSNAP INTersection OTRACK off OSNAP on Zoom?XP Lock Viewports Dimension Layer Current Center Marks Linear Baseline or Continue Diameter Holes Cylinders Radii Dress-up Different DimStyles Dimension Toolbar Decimal Places Pick / Right Click DO NOT Change the <> REF Double Click TYP Diameter Symbol Addition Countersink/Counterbore/Depth GDT Style 2

3 Conquering Dimensions One of the best features and the one that seems to be one of the most difficult features of AutoCAD seems to be Dimensioning styles. On the surface dimensioning is very easy, a couple of picks here a couple of Objects snaps there and a nice associative dimension appears. However, does the dimension have the characteristic that you really wanted and if not how easily is it changed without losing it's associativity? An answer that many CAD personnel have used is that of exploding the dimension. Terrible answer. Exploding dimensions defeats the whole purpose of AutoCAD's associative dimensioning. Upon explosion all connectivity with the actual dimension information, is severed. In this seminar we will cover how to take care of any dimensioning challenge without exploding. The main key to this is setting up dimension styles (DimStyles) and the use of dimension override (Command: DIMOVERRIDE... Alias:DOV). You should set up as few DimStyles as possible in order to get the job done properly for your needs. For example, I like to setup two basic dimension styles for my basic use, a Mechanical English and a Tolerancing style. Dimension scale affects the size of the dimension geometry relative to the objects in the drawing. Dimension scale affects sizes, such as text height and arrowhead size, and offsets, such as the extension line origin offset. You should set these sizes and offsets to values that represent their actual plotted size. Dimension scale does not apply the overall scale factor to tolerances or measured lengths, coordinates, or angles. Setting dimension scale depends on how you lay out your drawing. There are three methods used to create dimensions in a drawing layout: Dimension in model space for plotting in model space. This is the traditional method used with single-view drawings. To create dimensions that are scaled correctly for plotting, set the DIMSCALE system variable to the inverse of the intended plot scale. For example, if the plot scale is 1/4, set the dimscale to 4. Dimension in model space for plotting in paper space. This was the preferred method for complex, multiple-view drawings prior to AutoCAD Release Use this method when the dimensions in a drawing need to be referenced by other drawings (xrefs) or when creating isometric dimensions in 3D isometric views. To prevent the dimensions in one layout viewport from being displayed in other layout viewports, create a dimensioning layer for each layout viewport that is frozen in all other layout viewports. To create dimensions that are scaled automatically for display in a paper space layout, set the DIMSCALE system variable to 0. Dimension in layouts. This is the simplest dimensioning method. Dimensions are created in paper space by selecting model space objects or by specifying object snap locations on model space objects. By default, associativity between paper space dimensions and model space objects is maintained. No additional scaling is required for dimensions created in a paper space layout: DIMLFAC and DIMSCALE do not need to be changed from their default value of Note: When you dimension model space objects in paper space using associative dimensions, AutoCAD automatically adjusts dimension values for the display scale of each viewport. This 3

4 adjustment is combined with the current setting for DIMLFAC and is reported by the LIST command as a dimension style override. For nonassociative dimensions, you must set DIMLFAC manually. Needed Terminology Family - The dimension syle that includes the parent and all the children. Parent - The parent holds all the characteristics for the entire family. All the children will start out with the basic characteristics as setup in the parent. Child - There are 6 children for each parent. They hold the characteristics for each of the individual children; Linear, Angular, Radius, Diameter, Ordinate and Leaders and Tolerances. Starting with the Basics Every dimension that is created in AutoCAD, has a dimension style associated with it. The default DimStyle is "Standard". This is a great place to start. Whenever we change an individuals dimension's dimension style it will take on the characteristics of that style. Conversely, if the dimension style values are changed, the dimensions created with that dimension style will automatically be updated. At first, It seems it would be great to create several dimension styles that will take care of the finest details. But as we look at this we will find a huge pile of styles. A much better approach, I have found, involves having a few dimension styles to take care of the major characteristic needs and use a dimensioning override technique to "fine tune" the dimensions. 4

5 Creating a Dimension Style For this demonstration will create two families, Mechanical_English and Mechanical_English_Tolerance. We will start with "Standard" dimension style as our base reference point, and create Mechanical_English. Within Mechanical_English will will set the text height, arrow sizes, extension line settings, dimension text style, center mark size and type, base number of decimal places etc. The three children that will be modified and saved under the family of Mechanical_English, are Radius, Diameter and Angular. Dimension Styles Creating the Parent Creating Mechanical English Dimension Style Note: A Dimension Text Style must be made before completing this exercise Dimension>Style Notice Standard is the Default Dimension Style Pick New Button New Style Name: Mechanical_English Pick Continue Button Lines and Arrows Tab Dimension Lines Lineweight 0.25 Extension Lines Lineweight 0.25 Extend beyond dim lines 0.1 Offset from origin 0.07 Arrowheads Arrow size: 0.1 Centermarks for Circles Type: Lines Size: 0.07 Pick Text Tab Text Tab Text Appearance Text Style Dimension 5

6 Pick Fit Tab Text height 0.1 Fit Tab Fit Options Scale for Dimension Features Scale Dimensions for Layout Pick Arrows Radio Button Pick this Radio Button Pick Primary Units Tab Primary Units Linear Dimensions Precision.000 Text height 0.1 Zero Suppression Check Leading Angular Dimensions Zero Suppression Check Leading Pick OK Button Notice: The Dimension Styles Manager Dialog Box should appear Also, Mechanical_English should appear under Styles: Creating the Children Pick New Button Pick Use for: Pick Angular dimensions Pick Continue Button Pick Fit Tab Fit Tab Fine Tuning Check Place Text manually Pick Primary Units Tab Primary Units Angular Dimensions Precision 0.0 6

7 Pick OK Notice: Angular now appears under Mechanical_English Pick Mechanical_English under Styles Pick New Pick Use for: Pick Radius Pick Continue Now we are setting up the Radial type child underneath Mechanical_English Parent Pick Lines and Arrows Tab Lines and Arrows Tab Center Marks for Circles Type Mark Size 0.07 Pick Fit Tab Fit Tab Fine Tuning Check Place Text manually Pick OK Notice: Radial now appears under Mechanical_English Pick Mechanical_English under Styles Pick New Pick Use for: Pick Diameter Dimensions Pick Continue Now we are setting up the Diameter type child underneath Mechanical_English Parent 7

8 Pick Lines and Arrows Tab Lines and Arrows Tab Center Marks for Circles Type None Pick Fit Tab Fit Tab Fine Tuning Check Place Text manually Pick Mechanical_English under Styles Pick Set Current Button Pick Close Button 8

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