1.4. Together these are referred to as the control system. The control system automatically moves the machine during operation, but can also be used by the operator to manually move the spindle along the machine axes during tool setup.
CNC workflow
The workflow for CNC projects consists of three primary steps: designing, toolpathing, and machining, Image 1.5. Each of these has several sub-steps that we’ll discuss in later chapters, but the important thing to know is that they are each associated with a particular kind of soware. CAD (computer-aided drawing) for drawing; CAM (computer-aided machining), which converts the CAD drawing to toolpaths and machine code; and the Controller soware that communicates the code to the CNC machine and tells it where to move during the machining process. Don’t let that alphabet soup of leers intimidate you. Using today’s CNC machines has been simplified by advances in CNC soware that automates much of the complex processes of the past. With a lile practice, it will start to make sense, but first, let’s take a quick look at each type of soware.
Images 1.4: CNC machines connect to either a control computer or a control pendant. These allow the operator to control the movements of the CNC machine automatically and manually.
Image 1.5: A specific type of software is associated with each step of the CNC workflow.
CNC Router Essentials
CNC Basics : 1
CNC software
There are dozens of CAD programs that can be used 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 soware 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) soware 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 soware, 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 seing 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 aer 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 cuing. 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 cuing file
is then saved and loaded directly into the control soware from your computer or via flash drive to the computer or pendant that is aached to the CNC machine, Image 1.8.
Control soware 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 cuing, and then reading the cuing 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.
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:
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