While 3D printing has been getting a phenomenal amount of “buzz” in recent years, serious makers are still relying more heavily on CNC machining to complete their projects. While 3D printing is incredibly fun and versatile, it is subject to a range of limitations that make CNC machining the preferred choice for those attempting more “serious” work:
3D printers work with very few materials, unlike CNC machines
Typically any one 3D printer only works with between one and three materials; most consumer-priced models only work with ABS or PLA plastic, for example. If you want to work with wood or metal, very common materials in many projects (particularly when you need to create something practical, such as a replacement metal part for a car or machine), you’re generally out of luck.
CNC mills, on the hand, typically can handle plastic, metal, wood, wax, and just about anything else one can imagine. This allows the user to make prototypes in the same material that will be used for the final product (wonderful for things like strength and durability testing), or move right from design into final production.
3D printing is much slower than CNC machining
3D printing slowly creates objects by layering the chosen material, building it up in very thin sheets. This, naturally, takes a very long time, and there’s no way to speed up a 3D printer—it goes as fast as its manufacturer designed it to go, and that’s it.
As milling machines work by reduction rather than creation (cutting away material to create a shape) they can produce objects much faster than a 3D printer can. Starting from nothing is always going to be a slower process than starting from an existing block of material.
3D printing offers a limited range of quality settings
Due to the layered way in which 3D printers create objects, there’s not a lot of choice when it comes to quality settings—if you want to bang off a rough part fast to test a design, you’re out of luck. Each new design test will be a high-quality product painstakingly built up in layers. Naturally, this can get a bit tedious when one is experimenting.
CNC Mills, on the other hand, allow the user to freely trade quality for speed, allowing one to quickly dash off many rough parts for testing purposes, something which can greatly speed up a project’s overall development. CNC mills even allow the user to select different levels of quality for different areas of a part, so one can select certain areas that one wishes to test in a perfect state, and let the rest remain rough.
There are, of course, some applications where 3D printers still excel, such as the creation of certain shapes which CNC mills cannot so easily create. Likewise, they are the more “user friendly” of the two machines, making them a great gateway into the world of being a “maker”. Ideally, if one can afford it, one should invest in both machines so as to get the best of both worlds.
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