There’s nothing like creating something with your bare hands. That said, we’ve all been wrist deep in wood or metal shavings cursing whatever tool we’re using because our creation isn’t coming to life like we thought it would. Enter the multi-tasking technology of CNC machines.
CNC machines have long been a commercial staple, but they’re quickly gaining a footing in the hobby market. So, how do they work? This article focuses on hobby CNC machines as it’s likely that if you work as a commercial CNC machinist you have relevant training.
What Materials Are You Using?
The first step to using a CNC machine is deciding what you want to use it for. Is it for soft materials, such as wood and plastic, or is metalworking your forte? This dictates what type of machine you need. A CNC router is your tool of choice if you’re working with wood while a CNC milling machine is what you need for creating parts with metal.
Get To Grips With Software
All CNC machines use computer software to control their tools—hence the acronym: computer numerical control. The software is essentially a three-step process. The part is drawn in a CAD program (computer-aided design) before a CAM program (computer-aided manufacturing) converts the drawing into a code called g-code. The machine reads the g-code and makes the part. Some machinists write g-code straight into the machine, but most rely on the CAM program.
CAD programs are available to buy from most software shops, but you can also access free versions online. This free software is hit and miss, but it’s a good idea to try a free program to practice with before you invest in a more advanced package.
Once you’ve got the hang of your CAD software, try drawing a part you want to create. Use gridlines when drawing so you can be specific about your measurements.
When you’re happy with your drawing, export the file and import it into a CAM program. This is where things become more complex as you have to tell the software what types of tools to use, as well as how deep or fast it should cut. Once you’ve defined your tools it’s time to create the g-code for your machine to read—this is automatically created once you’ve finished inputting your information.
Commercial CNC machines usually transfer the g-code directly to the machine, but hobby machines are run by external PCs. These should have a machine control program and you upload the g-code to this program to get the machine moving. If you want to type g-code straight into the machine, find the g-code reference for your machine. You then type the commands straight into the program, bypassing the CAD and CAM process.
Tip: Typing g-code straight into a program is good for simple designs, but for more detailed creations it’s better to use CAD drawings and convert them using CAM. There are a number of websites that give you the basics for g-coding by hand and a simple Google search will help you find them.
Creating A Part
When you upload your code into the machine the fun really starts! Ensure your material is held in place, either by the machine or with a vice, then stand back and start the program. It’s fascinating to watch the machine cut out your design and what you end up with will be so much more precise than if you’d created it by hand—and you’ll save yourself hours of frustration, too.