Introduction: Welcome to CNC
In this class, you’ll learn everything you need to know to design and create your own CNC cut projects, whether or not you’ve got access to a CNC router. We’ll learn some useful 3D modeling techniques, how to create joinery, and talk about equipment and materials.
CNC stands for Computer Numerical Control. Simply put, it is a machine with a tool-holding head whose movements are controlled by a computer. Laser cutters, water jets, and CNC routers are all CNC machines. 3D printers are technically CNC machines as well, but they have additive tool heads (adding layers of melted plastic) as opposed to subtractive ones like routers (subtracting from stock by cutting or carving into it).
CNC machines are controlled using a very simple programming language called G-Code. With a 3-axis CNC machine, the computer tells the head to "move in the X axis 2.1 inches"... "move in the Y axis 1.3 inches"... etc.
This computer control allows you to quickly and accurately cut out a wide variety of stock (wood, plastic, metal, etc.) in just about any shape you can imagine. CNC machines can carve complex 3D shapes, cut 2.5D contours out of panels, and even cut out fabric or leather with a drag-knife setup.
CNC allows you to create a design in your CAD software, create a CAM setup (Computer Aided Manufacturing), and produce a physical copy of your design very quickly. One of the added benefits is that you can change your design and update your CAM setup to improve on it. You can also produce multiple exact copies of the same object.
Step 1: What You'll Learn
I think the CNC router is the most powerful DIY tool in the world. Although 3D printers and laser cutters are great for making all kinds of things, they're very limited when it comes to size and structure. With a CNC router and enough plywood, you can literally make a house. I made this 9' tall semi-permanent shelter for two campers using $250 worth of MDF, some flexible metal flaps, wood screws, and a CNC router...
PROJECT 1: Relief Sculpture
You'll learn the ins-and-outs of CNC through 3 projects. First, you'll use Fusion 360 with an add-in, and ArtCAM to create a relief sculpture from a photograph. I'll demonstrate this project on the Othermill, a desktop CNC machine, for this project.
PROJECT 2: Dining Table + Chairs
With the basic concepts covered, we'll move on to flat-pack design by making a full-sized dining table. We'll design it in Fusion 360, a free-for-life CAD modeling suite complete with a sophisticated CAM environment. We'll make this project on the Shopbot CNC Router, a machine shop tool that can be found in maker spaces worldwide.
Finally, we'll get some practice with more complex geometry by designing a flat-packed dining chair to go with the table. Since we're using CNC, we can make as many copies as we want in no time!
Step 2: CNC Design & Fabrication Process
1. Design + Model
The first step is to create and model your design in CAD (Computer Aided Design). We'll do this in Fusion 360, which we'll introduce you to and provide download links for in the next lesson.
When you're designing an object that you intend to cut out with a CNC machine, it's very important to first know the following:
- What's the size of your CNC machine's table? The size of the table will limit the size of the stock you can cut.
- What's the size and thickness of your material? You will always need to know this, but it's particularly important when you're designing parts with joints that fit together.
- What's the length and diameter of your end mill? An end mill is a cutting tool kind of like a drill bit or router bit that's specifically designed for clean, precise cutting of specific materials.
When you start your design knowing these three things, you'll be able to make smart choices about how to design the object.
We'll also get into parameters in the Fusion 360 design. Parameters are just variables you can apply to any part of a model. In our case, we'll use them to establish the thickness of the stock for the table and chair projects.
2. CAM Setup
CAM (Computer Aided Manufacturing) involves taking one or more 3D objects and creating a G-Code tool path that will cut out or mill the parts as desired. Another reason we're using Fusion 360 is that CAM is built into the software, so all you have to do is switch from one workspace to another to work on the CAM setup.
You'll also be able to change a design, then update the CAM setup to work with the changes you've made. This makes it easy to experiment and improve your designs as you cut out parts.
3. CNC Machine Setup + Operation
With your tool paths finished, you'll learn how to safely operate both a desktop and full-size CNC machine for the best results in 2.5D cutting and 3D carving.
Step 3: Tools, Materials, and Software
CNC Mill / Router: Not Required
Although it's great to have a CNC on hand to practice what you learn in the class, you don't have to own one to participate. The class is designed so that you can learn the design, CAD, and CAM parts of the process in order to prepare you for the day when you have access to a CNC.
There lots of CNC machines on the market and no shortage of DIY builds on Instructables. Like most popular products, they get better and cheaper by the day. Carbide 3D and Inventables both make easy-to-assemble kits for less than $2,000.00 that I would highly recommend investigating. Makerspaces and hackerspaces are popping up all over the world and public libraries are jumping on board as well, so pay attention to what's happening in your neighborhood.
The material taught in this class is applicable to any CNC mill or router you may have access to.
This is an awesome CAD / CAM program that leaves nothing to be desired when it comes to designing parts for CNC fabrication. It's got a simple, intuitive modeling environment, a sculpting environment for organic shapes, and a CAM environment that lets you easily translate your designs into g-code toolpaths that a CNC machine can understand. Despite the fact that it's a professional-grade 3D modeling program with a great user interface, it's free for life with an enthusiast license. If you make less than $100K per year using it, you'll never have to pay for it.
Wood / Plywood
Although you can CNC cut almost any material, I'll be demonstrating the process with solid wood for the carving project and plywood for the table and chair. These materials are available anywhere and are a great place to start.
Step 4: Join Us and Become a Hardcore Maker
I hope you'll join us and learn all about CNC. I really believe that these are the best digital fabrication tools available for makers. Whether you want to make small scale sculptural objects, plaques or signs, furniture, or bigger structures, you won't regret learning about CNC.