Layers – the misunderstood and often ignored property present with all AutoCAD entities. The layer of an entity can easily make or break your future success when creating AutoCAD geometry. Before you start drawing, a little bit of planning will make your results very useful.
Verifying the current layer when starting a drawing is something that all CAD users should do. Depending on your software, the functionality of what you create will be compromised. An example; AutoCAD Electrical (ACADE) requires specific layers of “wires” to connect smart electrical components. If the layer of a” wire” is incorrect, the core functionality of ACADE fails.
Unless specifically required to be otherwise, the current layer for an AutoCAD drawing should be “0”! By setting the current layer to "0", anything you draw will inherit the current layer of a drawing into which you copy your newly created graphics. Blocks are another area of concern with incorrect layers. When creating a block from specific entities, their native layer will follow, thus embedding it in the newly created block. This will require using a block editor option to correct or will carry new baggage with each re-use.
See the screenshot below. Many entities in the drawing are on different layers for various reasons. If I was to add something to this layout and not verify the current layer, it could turn ugly. I want to add a center-line reference to the enclosure mounting holes for the assembly.
My layer of choice for the new geometry is “0”. If I jump right in without checking the current layer, I could get an unexpected result. Making layer “0” current before working will ensure that no extra or unwanted layer baggage gets created with your item. Verifying the proper active layer will also eliminate the need to revisit and correct things in the future.
See the screenshot below. I used a specific layer “frame” to create the frame assembly in this drawing. AutoCAD retains the layer as current since it is the one I have previously specified to draw on. Note that the current layer is “frame” since that is what I worked with as the last active layer.
If I do not go into the layer listing dropdown and change it, my new geometry will be incorrect. In the screenshot below, I have expanded the layer list. By simply selecting the proper layer (in this case, “0”) before drawing, I have solved my potential future problems. Below is the same dialog box, having changed my layer settings.
Note that by setting the layer to “0”, none of the remaining layers or their properties have been affected.
Bonus Tip – too many unresolved (unused or unreferenced) layers in a drawing will create problems later. I recommend people “purge” their drawing regularly to clean up these unused layers. After inserting and deleting blocks or drawing graphics, residual things are left in the drawing file. Below is the “purge” dialog box.
Select the ”Layers” option from the list and click “Purge Selected items.” Doing so will remove any unused layers. It will not remove the layer of any existing entities in the drawing!
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