Simple entities such as a lines, arcs, polygons can have thickness applied to them. Using lineweights, you can print drawings using heavy and thin lines to create emphasis. We would go so far as to say that every landscape drawing should be printed with lines of varying thickness. Just as heavy and thin lead pencils or pens are used in manual drafting, lineweights can be used to graphically represent different objects and types of information in CAD drawings. This gives life and vitality to drawings and makes them much easier to interpret.
To illustrate, the figure below shows a thicker line being applied to the walls and thinner line thicknesses to other entities in an architectural drawing.
Taking a very simple landscape example, the figure below shows a modular seating arrangement, a table with umbrella over the top and a specimen tree symbol in a container. Apart from the shrub symbol, there is little clarity in the drawing. Certainly, it is difficult to determine that it is an umbrella over the table.
Assigning line thicknesses (via the Properties box) to different entities in the drawing improves presentation. You may be able to see in the figure below that the drawing is no easier to interpret. For example, the polyline representing the back of one of the modular sofas has been assigned a line thickness of 0.25 mm.
Tip: It is really important to realize that you should not use lineweights to represent the exact width of an object. For example, if you want to draw an object with a real-world width of 150 millimeters, you should not use a lineweight; instead, use a polyline with a width of 150 millimeters to represent the object accurately.
Lineweights in model space vs. layout (Paper Space)
Tip: Lineweight display in model space does not change with the zoom factor. For example, a lineweight value that is represented by a width of four pixels is always displayed using four pixels regardless of how far you zoom into your drawing.
Tip: You can set the display scale of lineweights if you want the lineweights on objects to appear thicker or thinner at model space. Changing the display scale does not affect the lineweight plotting value. However, a drawing's redraw time increases with lineweights that are represented by more than one pixel.
Applying lineweights to an entity
It is possible to control line weights by setting the property of an entity implicitly through the Properties box or by setting line weight properties of the layer the entity resides on. Most drawings use a combination of the two methods so when the Layer manager is viewed, some layer show a line weight thickness while others show line weighs associated with a given layer. Our preference is to use layer settings to control lineweight wherever possible.
Applying line weights to different size plots
Some adjustment needs to be made when applying lineweights as the plot size (paper) is increased. In general, lineweights in drawings on A1 and A2 sheets needs to be in the range of 3.5 to 7 mm for maximum effect while on A3 size sheets, thicknesses can be reduces to the range 2.5 - 5.0
Turning on/off lineweight display.