CAD Design

The first step in the process of cutting something with a CNC is creating a 3-dimensional object of the item you are wanting to cut. Your first reaction to that statement may be “That doesn’t apply to me because I’m only interested in cutting out signs with are 2D.” This is true. However, the material that you are cutting from is three dimensional. A 3D object is anything that takes of space in three directions. A flat sheet of paper takes up space in 3 directions. It stretches left to right, front to back and (although small) up and down.

If you are able to find a CAD file community like the one we mentioned above, it’s possible you can get by without having to actually create your piece from scratch in the software. This can be a great time saver. Using a CAD program for the first time will require some patience. It takes time getting use to seeing and moving objects around on 3 surface planes. If you are just starting out with CAD software, getting a couple files from a community can be a great place to start as it will let you manipulate the pieces using the various tools available in the program.


Once you have created a 3D image of your item, you will need to convert it to a language that your router can understand. CNC routers operate using a language call G-Code. I like to think of G-Code like it’s latitude and longitude which you probably learned about in geography class during elementary school. It tells the router to move a certain number of steps (inches, feet, etc) in a certain direction.

To illustrate how CAD and G-Code work, imagine you are in New York City and want to go to Los Angeles. You need to look at a map to get there. The maps represents the image that you created using the CAD software.

The directions you come up with to get you from where you are (NYC) to your end point (LA) is your G-Code. If written similar to what your computer deciphers, your directions would read, “move south 800 miles. Then move west 2800 miles.”

Fortunately, software has evolved significantly over the past couple of decades and there is software that can easily convert your image into G-Code. It’s developed so much, that this can be completed in a matter of just a few seconds. Back when CNC machines were first created, operators had to manually created the G-Code themselves. Instead of using computers, this was done using punch cards where holes were literally punched into paper and then fed through the machine. The holes told the CNC machine how it needed to move.

Depending on the size and detail of your project, it is not uncommon for a project to take 50,000 to 100,000 lines of code to perform all of the required cuts. Fortunately, the computer does all this for you. It will create quick and efficient tool paths that will ensure your cuts are completed exactly as you intended.


The last step in the CNC process is the actual cutting of material. This is the step where all your work on the computer finally comes to life and you can watch a blank piece of wood transform into the object you created. This step of the process is actually the easiest for the operator. At this point, it’s up to the computer to execute the code that the operate created. The operator will need to stay close to the machine to ensure it doesn’t encounter any problems, but for the most part, nothing should be needed outside of keeping the area around the machine clean.

Types of Machines

There are three different ways a CNC machine can operate. The first type is simply a drilling machine. Just as the description says, these machines are focused solely on making precise holes using a drill bit. These machines are common in companies that produce car parts. Using a CNC machine ensures holes are drilled in the same spots on every piece that passes through the machine.

The next type of machine is a CNC lathe. These machines work much like a regular wood turning lathe. The only difference is that a computer tells a computerized arm where to move along the piece of wood. It also tells it how much pressure to apply so it begins cutting away material. These setups can be excellent for people who create table legs or baseball bats. Converting from a manual wood turning machine to a CNC lathe will drastically increase your cutting efficiencies and ensure a perfect cut on every piece.

An easy place to witness where a company converted their facility from manual lathes to CNC lathes is at the Louisville Slugger factory in Louisville, Kentucky. They went from taking hours to cut a MLB baseball bat to a matter of minutes. In addition, they are now able to save each player’s bat specs so that they can ensure every bat they cut for a particular player is exactly the same.

The last type of CNC machine is certainly the most common one that you will see. This version is called a CNC router. The CNC router is the most versatile of the three. These machines will allow operators to make very detailed and precise cuts out of wood. In fact, even at a hobbyist level, it’s not uncommon to find topographical maps of an area cut from wood. Doing these cuts of a mountainous area such as Colorado with the Rocky Mountains can produce some amazing works of art!