AutoCAD & AutoCAD LT All-In-One Desk Reference For Dummies (2006)

82 A Layered Approach

On/Off

Freeze/Thaw

Lock/Unlock Plot/NoPlot

Figure 5-4:

Toggle layer modes by clicking their icons.

The four layer modes are

On/Off: Objects on the layer are visible if mode is on (the light bulb is switched on) and invisible if mode is off (light bulb is switched off).

Strangely enough, the current layer can be turned off; it’s even possible to draw on a layer that’s turned off, as long as it’s current. So if you start drawing lines that don’t appear on-screen, check the layer mode!

Freeze/Thaw: Objects are visible if layer is thawed or invisible if layer is frozen. The difference between Off and Frozen is that frozen layers are not included when AutoCAD has to recalculate its numeric database. A glowing sun indicates thawed layers, and a snowflake means a layer is frozen. You can’t set a frozen layer current.

Lock/Unlock: When a layer is locked, you can see the objects on it, you can select them, and you can even draw on it. But you can’t edit objects on a locked layer. A padlock icon indicates whether a layer is locked.

Plot/NoPlot: You can set this layer mode so that objects on the selected layer are visible but will not appear on a plot or print preview.

Modifying layer settings

You can access the Layer Properties Manager dialog box at any time by clicking the Layer Property Manager button on the Layers toolbar, or by typing

A Layered Approach 83

LA and pressing Enter. You don’t have to create all your layers when you start a new drawing; you can add (or remove) layers at any time in the drawing’s life.

Nonetheless, the most efficient way of setting up and managing layers in any drawing is to create them all at once, and make the appropriate property and mode settings while you’re creating them.

Setting layer color

The following steps explain how to modify layer properties and settings in the Layer Properties Manager:

1.If the Layer Properties Manager dialog box is not already open, click the LPM button on the Layers toolbar.

AutoCAD displays the Layer Properties Manager.

2. Select the layer whose color you want to change.

To select multiple layers, hold down the Ctrl key as you select them.

3.Click the square color tile in the Color column.

AutoCAD displays the Select Color dialog box (see Figure 5-5).

Figure 5-5:

AutoCAD’s standard colors — all 255 of them.

4.With the Index Color tab current, select one of the large color tiles near the bottom of the dialog box, and then click OK to close the dialog box.

AutoCAD closes the Select Color dialog box and returns focus to the Layer Properties Manager. The foreground color of the sample rectangles

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84 A Layered Approach

changes to the selected color, and the layer shows the new color and name under the Color column.

For more information on using color in AutoCAD, see the “Using AutoCAD’s color systems” section later in the chapter.

Setting linetype

There’s a wrinkle to setting linetypes in an AutoCAD drawing. Unlike colors, which are always available, non-continuous linetypes are defined in an external file that goes by one of these filenames:

acad.LIN: The default linetype-definition file, designed for use with Imperial units drawings and based on inches.

acadiso.LIN: The default linetype-definition file designed for use with

metric units and based on millimeters.

acadlt.LIN: The AutoCAD LT version of acad.LIN. (Prior to AutoCAD 2007, this file was named aclt.LIN.)

acadltiso.LIN: The AutoCAD LT version of acadiso.LIN. (Prior to AutoCAD 2007, this file was named acltiso.LIN.)

For an explanation of the different linetype definitions, see the “Using linetypes” section later in the chapter.

You can load linetypes as a separate step, before you create your layers by choosing Format Linetype to display the Linetype Manager dialog box. Alternatively, you can follow these steps to access Linetype Manager through the Layer Properties Manager:

1.If the Layer Properties Manager dialog box is not already open, click the LPM button on the Layers toolbar.

AutoCAD displays the Layer Properties Manager.

2.Select the layer whose linetype you want to change.

3.In the Linetype column, click the word Continuous.

AutoCAD displays the Select Linetype dialog box. By default, only the Continuous linetype is loaded.

4.Click Load to display the Load or Reload Linetypes dialog box.

Load or Reload Linetypes displays all linetypes defined in the current linetype definition file (see Figure 5-6).

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Figure 5-6:

Linetypes galore.

5.Scroll through the list and select the linetypes to load, and then click OK.

Hold the Ctrl key to select more than one linetype. Load or Reload Linetypes closes, and the focus returns to the Select Linetype dialog box.

6.Select the linetype you want to assign to the selected layer in the Layer Properties Manager, and then click OK.

The Select Linetype dialog box closes, and the selected linetype is assigned to the layer (see Figure 5-7).

Figure 5-7:

Many clicks later, a linetype is assigned.

86 A Layered Approach

Setting lineweight

Lineweights are like colors — they’re always present and available, unlike linetypes which have to be loaded into the drawing before they can be assigned.

Lineweight is a display property that shows a representation of the relative thickness of different drawing objects. Lineweight works differently in model space and paper space:

In model space, lineweight is based on a number of pixels, so that no matter how close you zoom in — or how far you zoom out — linework always appears to have the same visual thickness.

In paper space, lineweight is part of the representation of the paper drawing. If you put linework on a paper drawing under a magnifying glass, the lines would appear thicker, and that’s exactly how it works in paper space — as you zoom in, the lines appear thicker.

The following steps explain how to assign a lineweight to a layer:

1.If the Layer Properties Manager dialog box is not already open, click the LPM button on the Layers toolbar.

AutoCAD displays the Layer Properties Manager.

2.Select the layer whose lineweight you want to change.

3.In the Linetype column, click the word Default.

AutoCAD displays the Lineweight dialog box (see Figure 5-8).

Figure 5-8:

Scroll to set a default lineweight for your layer.

A Layered Approach 87

4.Scroll down the list to find the desired lineweight.

Because plotter pens were traditionally sized in millimeters, AutoCAD’s lineweights are also displayed in millimeters whether metric or English units are configured.

5.Select the lineweight, and then click OK.

The Lineweight dialog box closes and focus returns to the Layer Property Manager.

Assigning lineweights to layers is only half the story. You also need to press the LWT button on the status bar to display the lineweights. When the button is selected, lineweight display is enabled; when the button is not selected, all geometry appears in the default line width, which is one pixel.

The lineweight property can be applied to hard copy as well as to the visual representation of drawing objects. We tell you more about that in Book VII.

Setting layer modes

As already noted, the layer modes are toggles that let you control layer visibility, the amount of drawing data that’s included in AutoCAD’s math calculations, whether a visible layer’s objects can be edited, and whether a visible layer’s objects will be plotted.

The following procedure runs through the four layer modes in the Layer Properties Manager dialog box:

1.If the Layer Properties Manager dialog box is not already open, click the LPM button on the Layers toolbar.

AutoCAD displays the Layer Properties Manager.

2.Select a layer whose mode you want to modify.

3.To toggle a layer’s visibility on or off, click the lightbulb icon in the On column.

4.To freeze a layer’s data from recalculation and turn off its visibility, click the Sun icon in the Freeze column. To thaw a layer, click the snowflake icon.

5.To lock or unlock a layer to prevent or allow its objects to be edited, click the padlock icon in the Lock column.

6.To prevent or allow objects on a layer to be printed, click the Printer icon in the Plot column.

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The Layer Control drop-down list

You have to use the Layer Properties Manager dialog box to modify layer properties, including color, linetype, lineweight, and plot style. You can also turn layer modes off and on in the Layer Properties Manager, but if the latter is all you need to do, there’s a more efficient way than opening and closing a dialog box.

The Layers toolbar contains a drop-down list of all the layers in a drawing (see Figure 5-9).

Figure 5-9:

Switch layer modes in the Layer Control drop-down list.

You can click the down arrow (or inside the list box) to expand the list, and then perform any of the following actions:

Set a layer current by clicking the layer name.

Turn layer visibility off or on by clicking the light bulb.

Freeze or thaw a layer by clicking the sun or snowflake.

You can’t freeze the current layer.

Lock or unlock a layer by clicking the padlock.

After you change the mode, click anywhere outside the Layer Control list to close the list and return focus to the drawing.

The third icon shows a sun or snowflake superimposed on a rectangle. This mode lets you freeze or thaw layers in a layout’s viewport. We discuss this option in greater detail in Book VII.

Because the Layer Control drop-down shows a color tile for each layer, you might think you could click it to change a layer’s color, but you’d be wrong. Color is a property, and properties can only be changed in the Layer Properties Manager.

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Object Properties

In AutoCAD, all objects have properties. Every object in a drawing is created on a layer. Layers can have a number of properties assigned to them, and anything drawn on a specific layer takes on the color, linetype, lineweight and other “by layer” properties of that layer.

In addition to the properties that an object inherits from its layer, an object can have the following properties:

Color

Linetype

Lineweight

Plot Style

Object properties can be assigned directly (or explicitly) to objects, or they can be assigned to layers. For example, on a floor plan you might have a bunch of blue doors. The color blue may have been assigned to each individual door, in which case the color will be listed as Blue. Or the color blue may have been assigned to the layer on which the doors were drawn, in which case the color is listed as BYLAYER.

Is one method better than the other? We certainly think so. For example, you may draw a floor plan in which you make all the doors blue. Then you decide they should be green instead. If you changed the doors explicitly, you would have to go through the drawing and select each and every door, and then open the Properties palette and change their color to green. Alternatively, you could just open the Layer Properties Manager and change the color of the Door layer from blue to green. Obviously, one of these processes is easier than the other.

When objects do not have explicit colors or other properties set, they take on the properties of the layers.

We strongly advise you not to change the properties of objects in a drawing, but instead to leave their color, linetype, lineweight, and other properties set to BYLAYER. Applying explicit changes to objects can make them difficult to edit because you can’t tell on which layer the objects are located.

Using AutoCAD’s color systems

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In AutoCAD drafting, color has two main functions, neither of which is producing color drawings:

90 Object Properties

Color helps you differentiate objects on-screen. When you assign colors to layers, you can tell immediately if something is on the wrong layer if it doesn’t show up in the color you expect.

Using the traditional color-dependent plotting system, the colors of objects determine the thickness of the printed linework.

Recent releases of AutoCAD support three color systems:

ACI Color Index: The original and genuine 255 colors that have always been part of AutoCAD (see Figure 5-5).

True Color: A range of over 16 million colors you can set by dragging sliders or entering RGB (Red Green Blue) or HSL (Hue Saturation Luminance) values.

Color Books: Select colors using Pantone or RAL colors.

You may use True Color or Color Books colors if you were trying to match specific material colors. For most drafting purposes, the 255 standard colors on the ACI Color Index tab are adequate.

Don’t get attached to the idea of using True Color or Color Books colors if you’re using AutoCAD LT. AutoCAD’s lower-cost sibling supports only the 255 ACI Color Index colors.

Using linetypes

The four linetype files (acad.LIN and acadiso.LIN, and their acadlt equivalents) include 45 different linetype definitions, broken down as follows:

Twenty-four AutoCAD standard linetypes: 8 basic patterns (border, center, dashdot, dashed, divide, dot, hidden, and phantom) each in three spacing variants; for example, BORDER has normal spacing of its dash and dot elements; BORDER2’s elements are half the size of BORDER’s; BORDERX2’s elements are twice the size of BORDER.

Fourteen ISO 128 linetypes conforming to ISO/DIS 12011 specification: These are rarely used; we recommend you stick with the 24 standard linetypes, for Imperial or metric drafting.

Seven complex linetypes: These include symbols or text as well as dash-dot line patterns. Linetypes include fence lines, railroad tracks, and batt insulation.

In addition to these 45 linetypes, the acadiso.LIN and acadltiso.LIN files include an additional 14 JIS linetypes. While all the above linetypes will work

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for either Imperial or metric drafting, the JIS linetypes are for metric work only. And we still recommend the 24 standard linetypes for most drafting in metric or Imperial.

Setting Up Standards

In this chapter, we discuss the many settings that you can use to enhance your AutoCAD drawings. You may have observed that AutoCAD provides a great deal of settings, and if you’re like us, the last thing you want to do is go through those steps every time you want to create a new drawing.

The good news is, you don’t have to!

In Chapter 2, we discuss the various file types available in AutoCAD, and we explain how to create a drawing using a template (DWT) file. We point out that templates are fine as far as they went, but that you probably want to add settings (and maybe even objects) in order to make them really useful.

Everything that we discuss in this chapter — from layers, to linetypes, to text and dimension styles — can be created and saved in a template drawing so that they’re available to you in every drawing you start from that template. After going through this chapter, you know that you can add quite a few settings to a template to save yourself a great bit of effort for future drawings. In the chapters ahead, we look at annotation, inserting blocks, and other features that will enhance the usability of your template drawings as well.

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