Selecting the material for your CNC machine

CNC machines can be built out of a variety of materials. If you’re going to build a CNC machine, it’s up to you to choose the best material to do it with. One of the main things that will determine the best type of material to build your CNC machine with is what you’re going to be cutting with your CNC machine.


Wood, foam, and plastic are generally very easy to cut. Compared to metal, wood is very soft. This means that your machine does not have to be nearly as rigid or heavy as a machine designed to cut metal. In fact, you could easily build a CNC machine from wood, which was what I did for my first CNC machine. Building your machine out of wood is perfect if you don’t require great accuracy, and you are not cutting hard materials. Unfortunately, wood does have a tendency to warp over time. Because of that, wooden CNC machines are less reliable and last a shorter amount of time. If you do decide to build your machine out of wood, you’d be well advised to reinforce it with some aluminum bars. Hollow square aluminum bars from Home Depot or Lowe’s do wonders to reduce warping over time.

Building with plastics

The next step up from wood is plastic. Some plastics are more rigid than wood, and do not warp over time. If you have the tools necessary to work with wood, you have the tools too work with plastic. Plastics are an amazing material, and can come in a variety of forms. For example, I’ve seen a number of simple machines built out of clear acrylic sheets. HDPE, or high density polyethylene, is also a popular choice. This material is firm, easy to work with, and shouldn’t warp much with time. The only real downside of working with plastics is the cost. Plastics are several times more expensive than wood per square inch, so it is only practical to build small machines such as engravers using plastics. To calculate the costs of the type of plastic you’re interested in, you can go to TAP Plastics. They also have a number of retail stores which you can visit in person if you live nearby. The only thing you should be aware of is that sometimes when you buy a sheet of plastic it’ll be curved, not perfectly flat. Even tough plastics do bend when force is applied. Therefore, CNC machines built out of plastic are not suitable for building machines which will work with metal.

Building with metal

If you want a precision machine, you’ll need to build out of metal. Metal isn’t cheap, but it is often cheaper than plastics. Aluminum is easy to work with, and is still very rigid. Another huge advantage of metal is that it will never warp due to humidity like wood will. Unfortunately, working with metal is not like working with wood. In general, if you want to make a precision CNC machine out of metal, you will need to have access to a mill so you can precisely machine your parts. You can also design your parts and contract a local machine shop to make the parts for you.

Updated: July 3, 2018 — 4:36 pm
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