Plot Style Table Choice Changes Lineweights
A drafter plots a plan to PDF from a layout at 1:100 on A1. The drawing uses layers with colors 1 through 7 and lineweights assigned ByLayer, mostly 0.25 mm, with structural walls on a layer set to 0.50 mm. The office standard is to plot with a named plot style table (STB) in which all styles are set to use object lineweight. For this plot, the drafter selects a color-dependent plot style table (CTB) named MONOCHROME.CTB because the client wants black lines. The resulting PDF shows all lines at the same thin weight, and the 0.50 mm walls are indistinguishable from the 0.25 mm partitions. The plot preview looked correct on screen.
1. Explain why the lineweights collapsed and why the preview did not reveal it.
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The drawing's layers carry lineweights ByLayer, but the chosen CTB table maps colors to plotted lineweights. If MONOCHROME.CTB assigns a single lineweight to all colors (or uses a fixed weight rather than object lineweight), the per-layer 0.25 mm and 0.50 mm values are overridden at plot time. The result is uniform thin lines.
The preview can mislead because the plot preview may render lineweights according to the display settings rather than the actual plot style resolution, or the preview may be shown at a zoom where the difference is not visible. The reliable check is the plot dialog's lineweight display option and a test plot of a small area at full size, or inspecting the PDF at 100 percent zoom. The drafter should also confirm whether the CTB table's lineweight column is set to Use Object Lineweight.
2. Recommend the correct plotting configuration consistent with the office standard and the client's monochrome requirement.
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The office standard is a named plot style table (STB) with styles set to use object lineweight, so the drawing should be plotted with the office STB, not a CTB. To satisfy the client's monochrome requirement, the drafter should either use a monochrome STB that preserves object lineweight, or set the plot to monochrome through the STB's color settings while keeping lineweight set to object.
Practical steps: confirm the drawing uses named plot styles (the PSTYLEMODE setting and the layer properties), select the office STB in the plot dialog, verify in the plot style table editor that lineweight is set to Use Object Lineweight for all styles, and set plot options to plot with plot styles. Then produce a test PDF of a detail area and check that the 0.50 mm walls read heavier than the 0.25 mm partitions at full size. If the drawing is actually configured for color-dependent styles, converting it is a separate decision that should be raised with the CAD manager rather than changed silently before a client issue.