Object Properties

This page offers a quick overview of what layers, colours, linetypes and lineweights are, and how to make the most of them.

Layers:

What are layers?

Using layers in AutoCAD is like using transparencies on an overhead projector. The layers are transparent and perfectly line up with each other (Click to see demo).

Layers can be turned off or frozen so they become invisible, or on and thawed so that they are visible.

Drawing views are a composite of all visible layers. Note that a layer is visible if it is on and thawed.

Why use layers?

•  Place objects on different layers to control how objects appear on your screen and how they appear in plots. Each layer can have a different color, linetype, lineweight or plot style assigned to it, and this in turn can affect the objects placed on the layers.
   
•  Multiple plans can be created from one drawing file by controlling which layers are visible when plotting.
   
•  By placing objects on different layers, they become easier to manage.
   
•  Speed up your work by displaying only the layers you need for the task at hand to make your screen less cluttered and improve your system performance.
   
•  Create consistent, correct drawings by using a standard set of layers, linetypes and colours. By sharing these layer, linetype and colour standards with others, drawings can be exchanged easily..

Working with layers:

Each layer can have:

A name :

up to 255 characters long - the name can include the following characters: A-Z, 0-9, and the $, _ , and - characters. The layer names should be consistent - please review the Sheridan Layering Standard.
 

 

A default colour:

the colour is normally one of the standard 256 colours in the AutoCAD Colour Index. It is strongly recommended that you use one of the colours from the Sheridan Colour Standard.
 

A default linetype:

this varies depending on the type of drawing created - currently there are no general guidelines for using linetypes.
 

A default lineweight:

this is new in AutoCAD 2000 and AutoCAD LT 2000, and did not exist in older versions of AutoCAD.

Traditionally in AutoCAD you would assign colours to layers and objects, and these colours would be "translated" into linetypes when plotting. The vast majority of AutoCAD users still follow this system, and have not started working with lineweights yet.

In the future, lineweights may play a more important role in setting lineweights when plotting, today they are used as the exception in a few rare cases.

A default plot style:

this only works with drawings created based on named plot styles - currently these are rarely used and there are no general guidelines for using these styles. They are beyond the scope of this lesson.
 

The current Layer

New objects created by draw commands are placed on the current layer. Think of the current layer as the "top" layer of a set of overhead transparencies - you can draw only on this layer.

The current layer cannot be frozen, and it is recommended that the current layer not be "off", as the user will be drawing "blind".

Most AutoCAD Users start by drawing on Layer 0: a standard system layer in AutoCAD.

Users can select a different layer name from the layer drop-down list to change the current layer, or use the LAYER command dialog box to set the current layer.

They can also use the first Object Properties toolbar button to Make Object’ s Layer Current.

Objects do not have to be on the current layer to be copied or modified, though.

Status of Layer Settings

You can change status of four layer settings in the Layer drop-down list on the Object Properties toolbar.

Simply left-click on the appropriate icon beside the desired layer name in the Layer drop-down list to toggle the status of each setting.

ON/OFF setting:

this makes objects drawn on the layer appear invisible, as if they were drawn in invisible ink. This status does NOT have an effect on drawing extents, the objects are still "there" in the drawing, but are invisible.
 

Frozen/Thawed setting:

When a layer is frozen, all objects on that layer are completely ignored by AutoCAD as if they were never drawn. The objects do not appear on screen.

The drawing extents is the area occupied by objects on Thawed layers so this setting can affect drawing extents.
 

Locked/Unlocked setting:

Use this setting to protect objects on layers that you do not want to modify in edit commands. Objects on locked layers cannot be selected, therefore they cannot be modified.
 

Plot/No Plot setting:

Controls whether objects will appear in plots.

Objects will appear in plots if the layer they are on is ON and THAWED and is set to PLOT.

A good use for this setting is to create a non-plotting layer for notes on the drawing that are "personal production" notes, and will not be plotted with the other objects.

Changing Object Properties:

The simplest way to change the general object properties is when no command is running :

•  select the desired objects (the command prompt area should be prompting you for a "Command").
   
•  select the desired property in the drop-down lists of the Object Property toolbar.
   
•  press the Escape key (Esc) twice to clear the selected objects & grips after they have had their properties changed.