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Design Software Concepts
2 There Are (at Least) Two Kinds of Design: 2D vs 3D
Sometimes you will have a simple drawing of something to be cut out. The design is drawn in a single flat plane. It is often drawn using the CAD functions of your software or with a CAD program (AutoCAD, for example). It can also be drawn with a “vector” drawing program (such as Adobe Illustrator). Whether a CAD design or vector drawing, it is essentially a flat, 2D plan of the project.
With this 2D plan, you will then use the CAM functions of the software to add information about the depth of cuts that are needed for the lines in the plan – frequently the depth will equal the thickness of the material. When the toolpath is generated by the CAM software, up and down movements are added to move the cutter in and out of the material for each cut. Further, the CAM functions can be used to have some areas of the plan cut or pocketed at different depths. So, while the design is a 2D plan, that plan is used to make a toolpath that has motion in all 3 directions, including the up and down actions of the vertical or “Z” axis. However, because the ups and downs tend to be straight movements in and out of the material, this type of work is sometimes considered 2.5D. Cutting plywood parts for cabinetmaking from a flat, 2D plan would be a good example of a 2D design turned into a 2.5D cutting project.
There is an additional and useful cutting technique that can be done with a 2D design file. It’s called “v-carving” because it makes use of a v-shaped cutter. This technique creates CNC motions with the v-shaped cutter that give an impressive chiseled look to lettering and other shapes. The CAM software uses the shape outlines in the 2D design to compute the 3D angled moves required to pull in and out of the material in such a way as to create a precise chiseled appearance with sharp corners. The design used for v-carving is still 2D in nature, but the actual CNC movements that create the effect involve full 3D, simultaneous XYZ motion of the cutter that can be quite complex. V-carving is a great way to add a more dramatic look to your lettering or sign work and decorative wood carvings. Because the layout process is still in 2D, it is relatively easy to create the designs and the v-carved letters can be cut fairly quickly.
In full 3D machining, your CNC cutter tip follows angled paths or 3D curves in order to mill or carve complex shapes. In 2.5D, your cutter may have been moving in 3 directions in situations like v-carving, but you were still thinking (designing) in 2D. In order to do fully sculptural 3D work, you need to think and design in 3D.
Designing in 3D is harder than 2D, but it takes full advantage of your CNC tool's capability to produce fully contoured shapes milled to your specifications. You will create the 3D shape of your concept in a 3D design system, defining the form that you want to cut. This shape is called a 3D model, and the software programs that do this kind of work are usually called 3D modeling programs (sometimes 3D CAD). Modeling is the right word here, because rather than drawing with lines, you build up your 3D object by inserting and modifying 3D shapes. Note that visualizing and conceptualizing 3D shapes on a 2D computer screen is difficult and will probably involve using new and unfamiliar computer graphics tools for manipulating objects and surfaces in 3D space. If you do not already have experience with this type of CAD software, you should appreciate upfront that it is going to take a little time to get comfortable with it.
The shapes that you can model and machine in 3D are nearly unlimited – which is great. But this capability also means that CAM work can become more complex as a result of the wide range of machining strategies (different types of toolpathing actions) that become available. Because 3D work is often done in blocks of material of various sorts, thickness and varied material characteristics require extra attention for CAM planning and are a further challenge for 3D projects.Previous Concept