Organizing drawings with AutoCAD - 5 Section

CHAPTER 22: LAYERS (Layers)

When I was a kid I was fascinated to see the sideboards of the large stationery stores of the Historic Center of Mexico City. In them you can find drawing equipment and the plastic arts that, just by seeing them, make them want to use them. There are rules and squads of all kinds, boats with brushes of various sizes and thicknesses, oil painting collections and pastel colored jars; gleaming cases with sponge or foam rubber interior protection, which contain precision bars and other fine instruments. All decorated with colored papers, billboards and even human figures of wood.
Of all those mesmerizing products, there were two that caught my attention, although today their days are probably numbered because of the PC and programs like Autocad, if not they have already disappeared completely. One of them was a metallic artifact with a hole where a Chinese ink pen was adapted and a leg that served as a guide on some letter templates. They called it “crab”, I imagine because of its shape, and it served, precisely, to make all the text of the plans with Chinese ink.
The second was a kind of press that adapted to the top of the drawing tables. When the lid was removed, it had small circular posts in which acetates with drawings were inserted. These posts served to perfectly align these acetates, so that the combined drawing of several avoided the need to make new plans. If he wanted to see the drawing without a certain element, for example without dimensions, he would remove the acetate that contained them and draw a blueprint of the rest, giving rise to a plane.
The method had unquestionable advantages, of course. If several drafters were involved in the drawing of plans, then each could focus on a certain element. In the design of a building, for example, all the drawings could have as a common component the boundaries of the land, then in an acetate could be placed only the foundation plans, in others the walls per floor, in others plus the electrical and hydraulic installation . If you wanted to see the walls together with the doors and the electrical installation, then the corresponding acetates were aligned, which saved a lot of work.
With this principle in mind, in Autocad we can use layers. We must define a name for each one and decide on which layer each object will remain. In this way, and as we will see in the following sections, we can activate or deactivate the layers, making their elements appear or disappear from the drawing, as if we were adding or removing acetates. In addition, with the layers it is possible to control in an organized way the determination of the properties of the objects. For example, for the "hidden lines" layer we can define a blue color and the line style to be dotted, as we saw in chapter 7. Thus, all the objects that are located in that layer will have that color and that color. style. With what the creation of new plans already depends only on the plotters (plotter) and the printers and not on removing or adding elements before printing.
It must be said that the definition of how many layers to use and what names they will have can be decided by you, of course, depending on your specific work. But in the different industries there are already standards for the use of layers. These standards vary according to the specific industry and may also have particularities in each company. So it would be long and unsuccessful to abound about it. Do not forget, then, that working with Autocad in corporate environments involves knowing the criteria used to name layers and even others related to line styles, dimension styles, colors, and so on.
Another useful observation is that the use of the layers must be planned before starting the elaboration of objects. While it is possible to create layers at any time in AutoCAD, the truth is that this could force the user to relocate already processed objects layer, which could result in more work than necessary.
This could lead the reader to wonder why we did not see the layering issue prior to the making of the objects. What happens is that I present the subject of the layers in this section, and not before, by attending to a criterion of didactic exposition, which does not always coincide with the real order in which, in practice, the programs are used.
So we insist that the creation and use of the layers is part of the previous planning of their work, but it did not make sense to expose it before even creating an object with Autocad, because it would have turned out to be a concept too abstract.

22.1 Creating layers

To create layers, name them and define their color properties, line style, thickness, and stroke style, we use the Layer Properties Manager, which appears with the first button in the Layers section of the Home tab. It is a dialog box that consists of two panels. The one on the left shows a tree view of the groups of recorded layers and filters, which we will study later in this chapter. On the right is the list view, which shows the layers according to the group or filter specified on the left. In that panel we see its name and its various properties.

As you can see, by definition there is a layer called 0. This layer has singular properties that we will study in the next chapter dedicated to the blocks. If we do not create a layer, all objects belong to the 0 layer and acquire the properties that this layer has, unless we define individual properties of color and line thickness.
To create a new layer, we use the corresponding button in the toolbar of the Administrator. The names of the layers can contain up to 255 characters, but as it usually happens in these cases, short names, but sufficiently descriptive, are better. In addition, we already mentioned that if you use AutoCAD in a company, it is most likely that you have to follow the rules in this regard.
Once a layer is created, we can indicate its color, thickness and line style properties by double-clicking on the property to be changed. What will give us the dialog boxes that we have already seen in chapter 7.

The Plot Style property is a topic in the 30 chapter, but let's say that it is possible to define that the objects in each layer are printed with different thicknesses and line colors than the layer has, according to a layout style, so that the printing a plane is more flexible.
Another possibility that the Administrator gives us is that we can select which layers are going to be printed and which layers are not. With a click on the corresponding icon in the Trace column, we will prevent this layer from being printed. Thus, we can add to our drawing, in a layer for that purpose, objects that serve as reference or information relevant to work, but which should not be left in the final planes.
If we have already created all the necessary layers, we can make one of them the active layer, so that all the objects drawn from that moment on belong to that layer. To do this, we click on a layer and then use the corresponding button on the toolbar. A double click on the layer has the same effect. In any of these cases, the "Status" column reflects the condition of the layer. If we are in the drawing area, we can change the layer by selecting it from the list of layers in the ribbon section.