Epoxy granite is a material that has been gaining a lot of attention in the DIY CNC community for its ease of use and damping characteristics. However, there are some drawbacks to using epoxy granite that you should be aware of before you decide to switch to it for your next CNC build.
What is epoxy granite?
Epoxy granite, also known as polymer concrete, is a material made from a mixture of epoxy and granite aggregate. It is often used as a construction material or for making countertops, floors and other surfaces. Epoxy granite is strong and durable, and it can be shaped and molded into nearly any form. It is also resistant to heat, chemicals and impact — and it has beneficial damping characteristics.
How is it made?
Epoxy granite is a material that is made by combining epoxy resin with granite powder / aggregate. It is a strong and durable material that is often used in the manufacturing of countertops and other surfaces.
What are the benefits of epoxy granite?
Epoxy granite is an increasingly popular material for DIY CNC machines. It is strong and durable, yet relatively lightweight (vs steel) and easy to work with. In addition, epoxy granite is non-conductive and has excellent vibration damping properties, making it ideal for use in CNC applications.
While it is known for its damping properties… it is actually not that good versus alternatives.
So while epoxy granite is approximately 3–5× better in damping vs an empty steel tube, there are other alternatives which exceed that by ~50×.
Source: Durfill — Fraunhofer-IWU.
I’ll write a post about what damping actually is, which materials have which properties, and so on.
Epoxy granite is also harder to work with than it looks
Finally, epoxy granite can be difficult to work with if you don’t have experience. It requires special tools and techniques to ensure good end results.
What are the alternatives to epoxy granite?
Epoxy granite is a popular material for DIY CNC machines, but it’s not the only option. Other materials like UHPC (ultra-high-performance concrete) or other polymer concretes — like Durfill — can also be used to build a CNC machine. Each material has its own advantages and disadvantages, so it’s important to choose the right one for your project.
Which epoxy to buy?
As epoxy granite is a mix between epoxy and generally sand or other additives, you don’t need a specific epoxy to enable that. It must be noted that with these DIY solutions it is best to experiment with mixtures on a small scale before you make parts out of it or fill cavities on your CNC router or CNC mill.
There are various recipes floating around on YouTube and for example CNCzone. The best bet is to get your inspiration there.
FAQ
Planning a build? Come discuss materials in the Discord — I’d rather help you pick the right fill up front than fix a finished machine later.
