Basics about CAD layers

CAD drawings range from the simplest with a few hundred geometric objects to the most complex ones with millions of geometric objects.

To better control the display and plot of geometric objects, CAD have introduced the concept of layer. This way, CAD users can put different geometric objects on different layers and control the color, linetype, lineweight and other properties by customizing the layer properties. The properties of some CAD objects are set bylayer by default and putting those objects on the specific layers will save you time and there is no need to customize them respectively.

The following are some important concepts and functions about layers to help us make the most of layers in CAD.

* introduction to layer setup

If we are just doing practice, then we could skip the setup of layer and just draw all the stuff on the default layer 0. But if we are creating some real drawings, it’s necessary to customize the layer setups.

There is no such a standard of how you should control the displaying or plotting of your drawing, it varies from person to person and industry to industry.

Normally speaking, drawings of mechanical parts are relatively simpler and architectural drawings tend to be more complex with all the walls, windows, doors, dimensions, text, etc.

If you are using professional software which has pre-defined layers, you don’t have to do the layer setup yourself because when you’re drawing, the software will automatically put the objects onto specific layers.

We don’t have to do the layer setup from the very beginning of the drawing, but we suggest doing so.

* How to set up the current layer

“Current” is a most commonly used word in CAD software, we also have current color, current linetype, current text style, etc. When we create a new object, the current properties such as current color, current text style, current linetype will apply to the newly-created object. So all newly created geometric objects and newly inserted blocks will be on the current layers.

If we didn’t select any object, then the layer displayed in the toolbar or command panel is the current layer, as shown in the following picture,

If we have selected an object, the layer displayed in the tool bar is the layer of the selected object, not necessarily the current layer, as shown in the following picture,

The current layer displayed in the Layer Panel will change accordingly when you select different objects. The current layer will remain unless you select a new one.

There are two main ways to set up layers.

1.Select layer name in the drop-down list of Layer toolbar. We can use this way when there are not so many layers and when layer definition is relatively precise.

2. If the object to be created is on the layer that already has a certain object, then select this object and click on icon, or you can click the icon first and then select the object, as shown in the following picture,

The second way is very useful when there are many layers and we are not sure of the layer names. If we know layer names very well and are good at keyboard operation, you can try using variables “clayer” to set up the current layer.

* layer on/off and layer lock/freeze

We can improve our working efficiency by setting the visibility of layers. By locking layers, we can also avoid our drawings being modified accidentally.

Turning off layers and freezing layers may seem to have the same result, which both control the visibility of layers. However, turning off layers is to temporarily disable the display of layer objects and when we press CTRL+A, we can still select the objects whose layer is off. We can also set the off layer to current layer and draw on it. With layer freeze, no display data will be generated and the freeze layer can’t be set to current.

Additionally, freeze has something to do with viewport. When we don’t enter viewport, the Layer Properties Manager only has Freeze, which means all viewports have been frozen, but when enter layout viewport, the “New viewport freeze” will add to the Layer Properties Manager, as shown in the following picture,

We can freeze different layer on different viewport to meet the demands of plotting, as shown in the following picture,