This article addresses a common predicament for AutoCAD users: lineweights not appearing as expected in plots, particularly when generating PDFs. We’ll delve into troubleshooting steps, focusing on plot style configurations, PDF driver limitations, and lineweight control methods.
When encountering issues with lineweights in plotted drawings, especially within PaperSpace layouts with specific page sizes like 11″ by 17″, the first step is to understand your current plotting environment. The user in question is experiencing faded or non-existent lineweights despite having the “Plot Object Lineweights” checkbox ticked. This suggests a potential conflict or misunderstanding in how lineweights are being interpreted by the plotting process.
Understanding Plot Style Tables
The configuration of plot style tables is crucial for controlling the appearance of lineweights, colors, and other graphical properties in your plots. AutoCAD offers two main types of plot style tables: STB (Style-based) and CTB (Color-based).
- STB files: These tables allow you to assign lineweight, screening, color, and linetype to specific plot styles, which are then applied to objects in your drawing. This offers a more granular level of control.
- CTB files: These tables map object colors directly to plotting properties. For example, all red objects might be set to a specific lineweight and black color in the plot.
To check which type you are using, access the Plot dialog box (by typing PLOT or right-clicking a layout tab and selecting Plot). In the top-right corner of the dialog, under “Plot style table (pen assignments),” you will see either “None,” a filename ending in .stb, or a filename ending in .ctb. If this dropdown is grayed out, it may indicate that you are not currently using a plot style table, or that it’s set to control lineweights directly from object properties.
Lineweight Control Methods
How you control lineweights directly impacts their plotting behavior. There are two primary methods:
- Layer Lineweight Assignments: You assign a specific lineweight to each layer in your drawing. All objects on that layer will inherit the assigned lineweight.
- Direct Lineweight Assignments: You can override the layer lineweight by assigning a specific lineweight directly to individual objects (lines, polylines, etc.).
Understanding which method you are using is essential for troubleshooting. If the “Plot Object Lineweights” checkbox is checked, lineweights should theoretically be plotted as specified, regardless of whether a plot style table is in use or if the checkbox is grayed out. However, the actual display of these lineweights can be influenced by other factors.
PDF Plot Driver Limitations
Even with correct AutoCAD settings, the capabilities of your PDF plot driver can impose limitations. Some PDF drivers have a maximum resolution (e.g., 400 dpi) that can affect the rendering of very fine lineweights. A lineweight that appears thin on screen might be rounded up by the PDF driver to the nearest representable thickness, potentially making it appear thicker or even invisible if it falls below the driver’s minimum threshold. This can translate to line widths that are finer than the driver can accurately resolve, estimated to be around 0.0200″ in some cases.
Displaying Lineweights in the Drawing
It’s important to distinguish between the “Display Lineweights” feature within AutoCAD and how lineweights are actually plotted. The “Display Lineweights” option provides a visual representation on your screen to help differentiate objects with varying lineweights. However, this display is often an approximation, rounding lineweights to the nearest pixel on the screen. The percentage of differentiation can also be adjusted in your AutoCAD options, meaning what you see on screen is not always a true representation of what will be plotted to PDF or paper.
Further Troubleshooting
If the issue persists, consider the following:
- Test with a Simplified Drawing: Create a new, simple drawing with basic lines and assigned lineweights. Attempt to plot this to PDF to see if the issue is specific to your complex drawing or a general problem.
- Try a Different PDF Driver: If available, experiment with different PDF plotting drivers (e.g., DWG to PDF.pc3, Adobe PDF, or system printer drivers) to see if the problem is driver-specific.
- Attach the Drawing File: If possible, share a copy of your drawing file (preferably saved in an older format like AutoCAD 2007 to ensure compatibility) with proprietary information removed. This allows others to examine your settings directly.
By systematically addressing these points, you can effectively troubleshoot and resolve lineweight discrepancies in your AutoCAD plots.