CNC Router Essentials. Randy Johnson

to create CNC project designs. So, if you currently use a CAD program that you like, you can probably use it as a starting point. The basic requirement is that it needs to output a CAM compatible file such as a .dxf, .dwg, .skp, .eps, .ai, or similar vector-based file. A soware package that is compatible with many types of CNC machines is called VCarve Pro by Vectric. It’s popular because it combines both CAD (designing) and CAM (toolpathing) soware in one package. It was also developed specifically as a CNC application. It’s also

      one of the easiest to learn. We use VCarve Pro v8.5 for the illustrations in this book. If you use a different version, your CAD/CAM tools may vary from what shown. You can download a free demo copy at Vectric.com. If you use a different CAD or CAM soware, the steps will be similar.

      VCarve Pro has three main windows, Image 1.6. The CAD side is used to create lines, shapes, and text. It also contains tools for aligning and refining the elements in your design. The center workspace is used to create, edit, and view your designs and toolpaths in both 2-D and 3-D. The CAM

      Image 1.6: CAD software is used to create shapes, add text, and edit project designs. CAM tools convert the design into toolpaths. VCarve Pro software (shown here) conveniently includes both CAD and CAM in one software package.

      Design/Layout work area

      CAD toolsCAM tools

      

      CNC Router Essentials

      1 : CNC Basics

      side is used to create the toolpaths for your project. Creating toolpaths involves seing parameters, including the kind of bit, the type of cut, the depth of cut, the number of passes, and the feeds and speeds for the bit.

      One of the best parts of VCarve Pro is that aer the toolpath is created, you can preview the virtual results, Image 1.7. It’s a great way to proof your work, catch errors, and verify that your project looks correct before cuing. If everything looks good, you can save your toolpath through a process called post-processing (also part of VCarve Pro), which converts your toolpaths to machine code. Post processors are machine specific, so be sure you choose the correct one for your CNC. This cuing file

      is then saved and loaded directly into the control soware from your computer or via flash drive to the computer or pendant that is aached to the CNC machine, Image 1.8.

      Control soware usually comes with the CNC machine because it needs to be configured to match the machine’s mechanical and electrical setup, Image 1.9. Some machines use a pendant to control the machine, while others are hooked directly to a computer. Both contain similar functions for controlling the machine, because their primary function is to aid the operator in preparing the machine for cuing, and then reading the cuing file and directing the CNC’s movements.

      Image 1.7: One of the most helpful features of VCarve Pro is its ability generate a toolpath preview. The 3-D representation of your project will help you refine your design and find toolpath errors.

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      CNC Router Essentials

       CNC Basics : 1

      Images 1.8: Toolpaths are converted to machine code using a post processor. This step creates a cutting file that is usually saved to a flash drive and then transferred to the control software at the machine.

      Image 1.9: CNC machine control software is often brand specific, but they all contain many of the same options for controlling and monitoring the machine. Control pendants also have many of these control options built into them.

      Control setup

      Axis position controls

      Axis zeroing

      File run time

      Machine speeds

      Progress preview

      Code monitoring and editing

      CHAPTER 

      Design

      Essentials

      CNC project designsfall into two general types: -D line drawings and -D models. They can be createdin a variety of ways and even combined. In this chapter, we’ll look at:

      • Basic design types

      • The basics of creating and using -D line drawing

      • The basics of creating and using -D models

      • Sources of project inspiration

      6CNC Router Essentials

      2 : Design Essentials

      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 soware. 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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      CNC Router Essentials

       Design Essentials : 2

      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