Hi there, and welcome to another episode of Maker 101. In each episode of this series we spot light a specific tool, process, or machine into one nice, quick, bite sized episode, for you. Today we are talking about CNC Routers.
What is a CNC router?
A CNC router is a machine in the class of precise, computer-controlled equipment. The tool head is a spindle which holds a radially symmetric cutting implement called an endmill, also called a bit. By spinning this endmill very quickly, and controlling the path the endmill takes, you can cut away from, and therefore shape blocks of wood, plastic, foams, or metal.
A hand router is a common woodworking tool. It has this spindle and endmill, but you control its motion by hand to cut wood. By placing it in a CNC gantry that can control X, Y, and Z directions, you can accomplish much smoother and more complex shapes, with near perfection.
What are the parts of a CNC router?
Very simplistically, the parts of a CNC router are the gantry, which has motors and a timing belt setup to control the X and Y position of the tool head.
The tool head which has another motor to control the Z direction, or the height of the spindle.
And the spindle, which is the part that holds the bits and the spinning joint.
The gantry is usually on top of a fixed plate or frame where you put your material.
To secure your material on the fixed plate, you have clamps or vacuums, depending on the particular machine.
To clean the dust generated from cutting, there is usually a network of vacuums to suck it u, or a cover of some sort over the whole machine to keep the dust contained.
What are the types of CNC routers?
The main variation in CNC routers is material and number of dimensions of control. There are CNC routers that are made to cut metal, but most are made for woods, plastics and foams.
Most CNC routers control 3 dimensions: X, Y and Z, allowing you to get cool surfaces and shapes, but you cannot make overhangs and convexities in your CNC parts. However, there are CNCs that have a 4th axis that actually rotates your material along one axis to get another orientation. This can allow you to get overhangs along that axis of rotation. Some very complex CNCs have 5th and even 6th axes, allowing you to create virtually any shape.
The only limitation of 6-axes CNCs is that it cannot create closed hollow shapes, like an empty ball.
What are CNC routers good for?
CNC routers are a really good choice when you need something precisely cut and you may need multiple copies. If you cannot get it accurate enough by hand, you should consider using a CNC router. They give many projects a very finished look because they have machined finishes and are generally very clean. If you have a weird shape that can fit within the bounds of the machine, you should look into using a CNC router.
What are CNC routers bad for?
CNC routers may sometimes be too much for your task at hand. If you are simply trying to drill a hole, no need to set up a CNC for this task, just use a drill! However, if you have an irregular pattern of holes that needs to be precise, a CNC router would probably be a good choice. CNC routers require a lot of setup, power, and prep work to make cuts, so if you are thinking of using a CNC, you should justify if you really need to use one for your job.
Depending on the particular machine you are using they can also be very loud when running, and it can be hours of constant noise. Because another thing to consider is that cutting with a CNC router is time. Although “higher tech” than using traditional power tools for woodworking for example, using a CNC Router can often can take quite a bit more time than using an alternative method. For example, when Brooke hollowed out the undersides of the tabletops on our nightstand build just creating the hollow pockets was about a 2 hour carve per nightstand. To save time on the square outline of the tabletops we just had the router go part of the way through to give us a precise stencil that was easily cut on the bandsaw much more quickly than the extra time it would have added to the carve on the CNC router.
The point is that with CNC routers it’s important to consider if the level or precision is worth any potential tradeoffs depending on the situation. Oftentimes it absolutely is. However, there are times where is just isnt. The vast majority of the times we work with our CNC routers it is in conjunction with the rest of the tools in our woodshop. It is a tool that adds value to an existing shop, and not a magic machine.
How do I design for a CNC Router?
CNC routers require a special file type called a GCODE file. You can make these files by 3D modeling your final part, setting up how big your initial stock material is, and then telling the 3D modeling software the cuts you want to make to get to your final part.
Generating Gcode can vary from easy to difficult depending on how much control your software gives you and how complex your final design is. If you are making a box, it will likely be easier than if you were trying to make a chess piece, for example. If you are using a Computer-Aided Design (CAD) software to make your parts, you should make sure the software also has Computer Aided Manufacturing, or CAM software, in order to generate these GCode files. Another thing of note is that GCODE files are special to each CNC machine make and brand, so you need to make sure you have the right software to generate files for your machine.
What are the kinds of tools that can go in a CNC router spindle?
Some things you would specify as parameters when making gcode files is the speed of spindle, the gantry’s traversal speed, the density of the material you are cutting, and the types of endmills you are using. In addition to getting endmills with different diameters, you can also get them in different shapes that make cool cuts. For instance, a flat endmill is good for making flat surfaces, whereas you may use a round endmill to make smooth continuous contours. You can use a V-Carve bit to make calligraphy text. We are working on another Maker 101 video that will be coming uop soon diving a bit more into this topic.
The last thing we are going to touch upon in this video is Safety, because its important to have an understanding of with any tool. You always want to use safety glasses and a mask for dust, if your machine is open. If your machine has a hood, you should still strongly consider safety glasses. You may also want to get ear muffs to protect against the noise if your machine is very large. You should always be monitoring the cut as its going and be near the emergency stop button if something goes wrong. You should never put your hand near the gantry or the bit when the cut is in progress. You should make sure the bit is tightly inserted and your material is tightly clamped to the work surface so it doesn’t move.