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How do you set a model space scale?

Published in CAD Dimensions 3 mins read

Setting a model space scale depends on the software you're using. However, if we're talking about scaling dimensions within model space in CAD software like AutoCAD, this involves adjusting dimension settings rather than directly scaling the model itself. Here's how you typically do it:

Adjusting Dimension Scale in AutoCAD

The core idea is to tell AutoCAD how to translate measurements in model space to displayed dimension values. This ensures dimensions look correct when plotted on paper at a specific scale.

  1. Open the Dimension Style Manager: Go to the "Home" tab, then the "Annotation" panel, and click "Dimension Style." Alternatively, type DIMSTYLE in the command line.

  2. Select and Modify the Dimension Style: In the Dimension Style Manager, choose the dimension style you want to change (or create a new one). Click "Modify."

  3. Navigate to the "Fit" Tab: In the Modify Dimension Style dialog box, go to the "Fit" tab.

  4. Set the Scale Factor: Under "Scale for Dimension Features," you'll find options to control the scaling. You have two primary options:

    • Scale Dimension to Layout (Paper space): This is the most common and recommended approach. If checked, AutoCAD automatically scales the dimensions based on the viewport scale in your layout tabs. This means you don't need to worry about manually adjusting the scale factor; dimensions will always appear correctly at the intended plot scale.
    • Use Overall Scale of: If you uncheck "Scale Dimension to Layout (Paper space)", you must manually enter a scale factor. This factor represents the ratio between the plotted size and the model size. For example:
      • A scale factor of 1 means 1 model unit = 1 plotted unit (full size).
      • A scale factor of 2 means 1 model unit = 2 plotted units (enlarged).
      • A scale factor of 0.5 means 1 model unit = 0.5 plotted units (reduced).

  5. Apply and Close: Click "OK" to save the changes, and then click "Close" in the Dimension Style Manager.

Important Considerations:

  • Annotation Scale: If you're using annotative dimensions, the dimension scale is controlled by the annotation scale assigned to the dimension objects and the active viewport or model space. This system automatically adjusts the size and visibility of annotations based on the current scale.
  • Consistent Units: Ensure your drawing units are correctly set before applying any scaling.
  • Viewport Scales: Understand how viewport scales in paper space affect the overall dimension display. The viewport scale determines the zoom level within a viewport, and this, in turn, affects how dimensions are scaled if you are scaling to layout (paper space).

By correctly configuring the dimension style and understanding the relationship between model space, paper space, and viewport scales, you can accurately set the dimension scale to ensure dimensions display correctly in your plotted drawings.

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