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CCAD's AutoCAD Tutorials

Lineweights

AutoCAD 2000 provides several new methods of varying lineweights in drawings. Before exploring these new tools, however, let's take a look at how lineweights were previously set.

Pen Assignments

Pen Assignments (or mappings) have been the standard method of establishing varying lineweights within drawings. Originally, color numbers (1-255) were assigned or mapped to specific pen numbers used by a traditional pen plotter. The end user simply placed different pens in the pen carousel to vary the lineweight (or color) of the objects being plotted.

Pen Assignments dialog box, old method

Pen Assignments were still utilized as laserjet and inkjet technology became the standard, although the mappings have changed. With this new technology, the Pen No. setting referred to the color of the ink used and the Pen Width was actually the width of the line being drawn. It was still necessary to use different colors in the drawing to product varying lineweights on a print.

Pen Assignments dialog box, new method


Color Dependent Plot Style Tables

The concept of using the color of an object to determine the plotting charateristics exists in AutoCAD 2000 and is accomplished by using Color Dependent Plot Style Tables. Plot Style Tables have replaced Pen Settings as a method of mapping colors to the plotter. Among the supplied Plot Style Tables that ship with AutoCAD 2000 are MONOCHROME.CTB and ACAD.CTB.

ACAD.CTB maps the color numbers to the same pen number and is best used when creating a color print where the printed color matches the on-screen color. To use color to determine plotting characteristics, make a copy of ACAD.CTB and alter the Pen Widths for specific colors.

MONOCHROME.CTB maps each color number to pen number 7, which is black. This plot sytle table works nicely when using the new Lineweight option in AutoCAD 2000.

Assigning Lineweight By Layer

A new property, Lineweight, has been added to layers in AutoCAD 2000. Like Color and Linetype, Lineweight can be assigned to a layer and the line weight of an object determined by its layer association.

In the layer dialog box below, several layers have been assigned different lineweights. Notice that layers with the same color have been set to different lineweights. This is not possible when assigning line characteristics solely through plotting. If not specifically set, the lineweight used for the layer is the default drawing line weight.

Layer Properties Manager dialog box


Assigning Lineweight to an Object

Although objects can generally have their lineweight determined by their layer setting, it may be necessary to override the layer's lineweight setting and assign a lineweight directly to an object.

This can be accomplished in several ways. One is to select the object(s) to be changed and selecting lineweight override from the property toolbar.

In the illustration below, the lineweight is still assigned to the FURNITIRE layer, but the lineweight of the column as been assigned directly to the objects, overriding the lineweight setting of the FURNITURE layer.

overriding lineweights example

Summary

While AutoCAD 2000 still supports the use of color to determine plotting characteristics, there are several new, more flexible methods available. To control lineweight by layer or by ojbect, use the MONOCHROME.CTB plot style table to plot in black and use the Lineweight property within a drawing to vary the lineweights. Not only does this method allow ojbects with the same color setting to use different plotting characteristics, it ties the lineweights of the objects to the drawing, rather than the plotter. This is very helpful when a drawing is plotted by a variety of plotting devices.