The term “CNC” can be very scary for many, especially if you come from the machining industry, or perhaps you used to run a CNC back in the early-computer era, where these large industrial-looking machines used tapes and punch cards to function. When many people think about a CNC machine, they think about writing tons of code, needing to be a mathematician or requiring a ton of training. Well I have a lot of good news for you.
Today’s desktop CNC machines do not require a ton of training, do not require the need to write code and do not require special math skills (other than how to use a calculator). Now, of course, there are still large, expensive industrial CNC machines out there that DO require special skills and training to operate, but this article (and entire website) is focused on the personal desktop CNC machine and the beginner, hobbyist, or small business person.
So let’s start by answering the question, “What is a desktop CNC?”
In simple terms, a desktop CNC (can also be known as a “CNC Router”) is a computer-controlled machine that has a router or spindle mounted on it that holds a cutting too (end mill or router bit). The machines are typically gantry-based, whereas the bed is fixed, therefore the material is fixed, and the gantry moves in three directions of movement, often referred to as the X, Y, and Z axes. To further describe these movements, the machine will move front to back (Y Axis), side to side (X Axis) and up and down (Z Axis).
The computer controls the exact position of each of these movements and tells motors on each axis how much to move and in what direction. These motors are often called “stepper motors” on desktop machines.
Unlike a tradition AC or DC motor, A stepper motor is a brushless, synchronous electric motor that converts digital pulses into mechanical shaft rotations. Each rotation of a stepper motor is divided into a set number of steps, sometimes as many as 200 steps. The stepper motor must be sent a separate pulse for each step. The stepper motor can only receive one pulse and take one step at a time and each step must be the same length. Since each pulse results in the motor rotating a precise angle, which is typically 1.8 degrees, you can precisely control the position of the stepper motor without any feedback device.
As the digital pulses from the controller increase in frequency, the stepping movement converts into a continuous rotation with the velocity of the rotation directly proportional to the frequency of the control pulses. Stepper motors are very reliable, inexpensive and produce a lot of torque at lower speeds.
The stepper motor’s controller sends these pulses based on instructions coming from the computer in the form of G Code.
G Code is a programming language that is specific to CNC-type machines and 3D printers. Do you need to learn how to write G Code? NO! The software that we use today, especially for personal desktop CNC machines is simple to use and is based on more of a WYSIWYG (what you see is what you get) style format. Once you setup your job in the software, then you simply output that file to G Code by simply telling it to save the output file for the CNC and the software does everything for you.
Now that we got all that technical stuff out of the way, we can simplify things a little better.
The personal desktop CNC can move in 3 directions, X, Y and Z. Remember these axis as it will help you a lot as you start using your machine and you start making your own designs in the future. The total amount that each axis can move is dependent on the physical size of the machine. There are small desktop machines that move as little as 8 inches in both X and Y and 2.5 inches in Z. This size machine might be good for a jeweler or someone that plans to work on very small parts. While machines in the “desktop” category can be as large as 3 x 3 feet. While still there are larger CNC routers that can measure up to 4 x 8 feet and still be considered a “personal” CNC. Many can be made from kits or as a DIY (do it yourself) project. Regardless of the physical size the movements are all the same and the physical components remain the same from one machine to the next, at least in a general sense.
The image below shows the basic components of a personal CNC system. Keep in mind that there are some variations to this design but this is shown as a typical layout.
Now that you have a basic understanding of what a desktop CNC is and its most common components, you can now enter the amazing world of taking your creative ideas and designs and making them on your own CNC. While the journey is not always point-n-click, CNC Simplified is here to help you with every step along the way.