The basics of creating and using -D line drawing
• The basics of creating and using -D models
• Sources of project inspiration
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Using 2-D designs
A wide variety of CNC work can be accomplished using just 2-D lines, Image 2.1. Any CAD program can be used to create a 2-D line design, but designs must be saved as or converted to a vector line format to be compatible with the CAM toolpathing soware. A vector line is made up of points that represent the geometry of the line, Image 2.2. One big benefit of a vector line design is that you can scale it up or down without losing details or resolution. Most CAD programs can create vector line designs, Image 2.3. Common vector file formats include .dxf, .esp, .dwg, .ai, and some .pdf files. These various file formats
Image 2.1: A 2-D line design creates a part that looks like it has been cut out on a bandsaw.
Image 2.2: The basis of all 2-D CNC design work is the creation of vector lines. Vector lines are made up of control points, and can be scaled larger or smaller without losing any detail. CAM programs use vector lines to create the toolpath cutting files. VCarve Pro (shown here) contains CAD drawing tools that create vector lines by default.
Control point
Vector lines
CAD drawing tools
2-D vector line drawing2-D part
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Image 2.3: Most CAD programs are capable of creating the vector lines, which can easily be imported into a CAM program for toolpath creation. So, if you are currently using a CAD program that creates or exports vector line drawing (e.g., .dxf,.eps, .dwg) you can probably keep using it as your primary CAD design tool.
External vector drawing
Import
Vector lines
Part preview
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vector designs, bitmaps cannot be read by CAM soware and need to be traced to create useable vector lines. Some CAD soware packages (including VCarve Pro) provide a built-in bitmap to vector line tracing tool. You can even start with a hand sketch. Simply photograph it and import it for tracing. It’s a powerful way to create original hand-drawn CNC project designs.
are also easily read by most CAD programs. Predesigned vector art is also readily available online—some for purchase and some for free. It’s an excellent way to find high-quality designs for CNC projects.
Bitmap images such as colored clipart and high contrast photos provide another starting point for 2-D designs, Image 2.4. Some of the common bitmap file types are .bmp, .jpg, .gif, .tif, and .png. Unlike
Image 2.4: Images saved as bitmap file types provide another starting point for CNC designs. However, they must be traced to create the vector lines in order to create the toolpaths. Some CAD programs make this easy with an auto-tracing feature.
Import
Trace
Vector lines
Part preview
Bitmap image
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a single-sided model, such a carved door panel or sign. The second type is a two-sided shape, such as coin or fish. The third type is a full in-the-round shape, such as a coffee mug, human figure, or automobile. Each type becomes progressively more challenging to carve on the CNC. Single- and two-sided CNC 3-D carving are the most straightforward, and these are covered in the practice project chapters. Full in-the-round models, such as a car, can sometimes be carved using a multi-sided carving setup on a 3-axis CNC, but other 3-D models require a 5-axis CNC machine and advanced CAM soware.
Using 3-D models
CNCs excel in their ability to cut complex shapes, and this includes 3-D models, Image 2.5. There are some limits, but the first thing to understand is that 3-D models fit into one of three groups. The first is
Image 2.6: One bonus of using VCarve Pro is that it comes with a large collection of 3-D clipart models that can be dragged into the design area and quickly scaled to fit your project.
CNC compatible 3-D clipart models are also available from many sources on the Internet.
3-D clipart
Part preview
Image 2.5: A 3-D model creates a part that appears sculpted or carved.
3-D part
3-D drawing
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common and can be imported directly into CAD/CAM programs, such as VCarve Pro, to create the 3-D carving toolpaths. Be aware though, that .stl files, like bitmap images, lose resolution when they are scaled up in
If you find that you enjoy using single-sided 3-D models in your designs, you will find a rich supply of them available from various online sources. A 3-D clipart library in VCarve Pro also contains a large collection of single-sided 3-D models, Image 2.6.
