Most CNC software packages have the ability to recognize layers within a drawing and do different things with them depending on which layer an entity is on. (i.e. perhaps you put your annotations on a particular layer – the CNC ignores that layer, else it will try to cut your notes into your part!)
It can go even farther than that…a layer may signify the hole depth or even the tool to use during the cutting process – drill diameter, counter sink, counter bore, etc.
The problem is within the same part, you cannot have different edges/features on different layers. The work around I have always seen is to add sketch entities to the drawing view, and place those sketch entities on the needed layer.
This work around works well…but there is quite a bit of drawing work -or what if you want to automate the process with DriveWorks?
Aly Farber, of Farber Specialty Vehicles, ran into this exact same issue. She is using DriveWorks to produce the custom cabinets that go into their vehicles. Her goal was to send .dxf files of the cabinet cutouts directly to the CNC, and have the CNC cut out the cabinet parts without any user intervention.
First she starts with the cabinet face without any holes:
Then she makes a model of the holes:
Next she places these “holes” in an assembly with the cabinet face…since she can have several different hole sizes and depths, they are all placed in the assembly and she uses DriveWorks to place the correct holes in the correct location.
Now each “hole” can go on its own layer for dxf export.
This trick will work for DriveWorksXpress, Solo and Pro…except Xpres cannot automatically export the dxf file.