How to Choose the Right Stock for Your CNC Projects

In this Instructable, we are looking at how to choose the stock, or materials, for your CNC projects. Makera is a manufacturer of high precision and easy to use desktop CNC machines, as well as a company built by makers, for makers, in the era of makers. This Instructable is intended to guide users of all levels through getting started with CNC machines, specifically by looking at options for stock suitable for CNC production techniques.

While we are discussing stock compatible for the Carvera Desktop CNC and Carvera Air, similar concepts are applicable to a wide range of CNC mills or routers, suitable to different resources that you might have available. While we sell materials in our store, the Carvera and Carvera Air can work with a wide range of materials sourced from anywhere you choose.

In addition to writing and sharing how to select the right stock in this Instructable, we've also created a YouTube video as part of our Getting Started with CNC Machines series for additional information and support.

For additional information, support, and resources, visit Makera.com or check out our YouTube Channel and Wiki Page.

For this, you need a CNC machine and materials of course! As mentioned earlier, these concepts are applicable to a wide range of CNC machines, including mills or routers, as well as with a wide range of bits and projects. Through this Instructable, we're going to look at when and why you might choose one material over another, as well as outline what materials are suitable for a CNC Mill or Router when compared to another type of machine, such as a 3D printer or Laser.

But if you need a CNC or stock, we recommend you check out the resources in our store.

As you consider what type of stock you want to work with, you also need to consider the differences between CNC machines. CNC stands for computer numerical control, and there are many different types of CNC machines out there. While we don't refer to 3D printers or laser cutters and engravers as CNC's they work similar to mills or routers in the way they operate, and the types of design files needed to use them.

3D printers work through an additive process, and often print with a plastic-based material such as PLA filament or liquid resin depending on the type of printer you're working with. Laser cutters and engravers work by using a light source to burn material for cutting and engraving options, and are compatible with a variety of materials depending on the type of laser you're using. But all lasers are often limited by material thickness, typically not being able to exceed a cutting depth of about 1/2 inch depending on the material and power of the laser. Most lasers also cannot cut through metal, and there are many other materials that cannot be engraved due to harmful fumes that will be emitted during the burning process.

Alternatively, CNC Mills and Routers are subtractive manufacturing machines, meaning material is removed during the machining process through a cutting or drilling action in order to make your part. Through this manufacturing technique, a wider range of materials can often be used, from plastics to woods, or composites like carbon fiber, or even metals! And with these machines, you're not limited by material thickness, but instead the cutting tools you have available to machine your stock. Check out this Instructable to learn more about choosing the right bit.

Some CNC's aren't as versatile as others. But the Carvera and Carvera Air desktop CNC Mills are designed to be the most versatile and easy to use desktop CNCs available, compatible with a wide range of materials and operations. And in addition to the milling spindle, the Carvera and Carvera Air also have laser engraving modules which offers two different manufacturing processes in the same machine. This means you can engrave wood, cut fabric, carve metal, etch glass, or even make a printed circuit board!

So now that we know about the different types of CNC's and the material limitation you might run into depending on the machine you're using, let's dive deeper into how to choose materials for your projects!

For any project, its always best to work through an iterative approach where you test and prototype your projects in materials that are easier to work with. Even though this means you might run a project more than once, this approach often saves both time and money in the long run.

Let's say we're creating a complex project that is going to be machined out of aluminum. Before running this project using aluminum, we can test it out using a softer and cheaper material to make sure it machines correctly, or to catch any mistakes we may have made. This might save your bits or your machine, depending on the size of the mistake made.

Materials that are great for prototyping are styrofoam or epoxy tooling board as these materials can be cut quickly, but also don't wear down bits thanks to how softy they are. Machinable wax is also great, and by using the Carvera's built in vacuum, chips can be collected and recasting for recycling and reuse too!

Working with metals, such as brass, copper, or aluminum, are one of the biggest advantages in using a CNC Mill over a different type of CNC machine. When you choose to work with metal, you need to ensure your CNC has both the power and precision to do so, as well as consider cooling as the chips created while machining metal can be quite hot, wearing on your bits and creating a potential fire hazard.

Some CNC machines use a flood cooling method for metal, where liquid is poured onto the cutting surface to wash chips away. This works well for larger projects, or when working with hard metals such as steel or titanium.

The Carvera and Carvera Air are equipped with an Air Assist module, which uses a stream of air provided from a compressor to blow chips away. This is a very clean and easy to maintain system, and one that works great with softer metals such as aluminum, copper, or brass.

For metals, you need to ensure you're using bits that are designed for working with metals. One great bit to use for metal is a Spiral O' bit which can be used for a lot of different types of cutting operations, or Ball Nose bits which can machine 3D engravings. Metals also typically need a higher spindle speed, such as 12,000 RPM, and a slower cutting feed. See our speeds and feeds guide or this Instructable to learn more about setting Speeds & Feeds successfully.

Working with Wood is another common material for both Mills and Routers. When you choose to work with wood, you need to ensure you have a vacuum system connected to collect any dust, and we recommend you use an enclosed CNC as well, especially when working in schools or public makerspaces.

Both the Carvera and Carvera Air are fully enclosed, and the Carvera even includes an internal vacuum and dust collection system, making a suitable machine for working with in a smaller working environment. Alternatively, you could connect an external vacuum to either the Carvera or the Carvera Air for dust collection.

For Woods, you can work with a wide range of bits, from V-bits to Spiral O' bits. Woods are typically machined at a slightly slower spindle speed, such as 10,000 RPM, and can be cut more quickly depending on the bit and machine you're working with. See our speeds and feeds guide or this Instructable to learn more about setting Speeds & Feeds successfully.

Working with Plastic material is a commonality between Mills and Routers, as well as other machines like 3D printers and lasers. The benefit of using a CNC Mill over another type of machine is that you can work with any plastic. And the enclosure and vacuum system with the Carvera makes this a more clean and safe process too.

Acrylic, Polycarbonate, and Delrin are typically safe for lasers, but they are often limited to how thick you can cut. CNC Mills like the Carvera can machine through material in excess of 3 inches thick, and at a much higher speed than what a laser could do. Machining plastic bi-color stock is easy to do on a CNC, and can be done without masking the surface as there isn't any scorching like you might find on a laser, as shown in this tutorial. And when working with plastics that emit harmful fumes, such as ABS or PVC, Mills like the Carvera are the safest option as no smoke is created during the subtractive manufacturing process, and all chips are collected automatically in the vacuum while being retained by the enclosure.

For Plastics, you can again work with a wide range of bits, from V-bits to Spiral O' bits. Plastics are typically machined at a slower spindle speed, such as 10,000 RPM, and can be cut more quickly depending on the bit and machine you're working with. See our speeds and feeds guide or this Instructable to learn more about setting Speeds & Feeds successfully.

Composite materials, such as carbon fiber or fiberglass are typically challenging materials to work with due to their abrasive nature. But cutting these materials is no challenge at all when using a CNC mill like the Carvera or Carvera Air!

For composites, you need to choose a bit that exhibits a high wear resistance, such as a Corn bit. Corn bits can be used for both cutting and drilling operations, and work exceptionally well for machining composites or PCBs. Composites also typically machine at a higher spindle speed and slower cutting speed depending on the bit and machine you're working with. See our speeds and feeds guide or this Instructable to learn more about setting Speeds & Feeds successfully.

Printed Circuit Boards, or PCBs, can be made through an number of processes, but using a CNC mill is our favorite! A PCB blank is typically a fiberglass board coated with copper which can be machined to create a PCB for an electronic circuit.

But by using the PCB fabrication pack, you can make complex PCBs that are multi-sided, or even coated with a solder mask to insulate the copper for a more professional result. You can also use the Carvera's built-in laser engraver to engrave a silk screen layer on the surface of your PCB too! For more information, see this tutorial.

When working with PCBs, V-bits and Corn Bits are typically best, as well as drill bits for making holes. The Solder Mask Removal Tool is a specialty tool included in the PCB fabrication pack that allows you to etch pads on the a solder masked PCB. See our speeds and feeds guide or this Instructable to learn more about setting Speeds & Feeds successfully.

When working with fabrics like felt and leather, or even thinner fiber materials like paper, a typically CNC mill or router is not the best option. But because of the Carvera's built in laser engraving module and the optional module for the Carvera Air, these materials can be machined on your CNC too!

When working with a laser module, you need to ensure proper ventilation and eye protection is in use, which differs from typical CNC machining parameters. See this tutorial for more information about working with a laser module on a CNC.

While we didn't look at every possible stock option available in this guide, what we covered should be enough to get you started, and hopefully finding success for your CNC projects as you work to choose the best material for the job!

More things consider which are equally as important as the materials you choose are the speed and feed settings when preparing your projects, as well as selecting the right bits for your projects. You can check out more guides and videos we've created to support learning these concepts, along with more how to's and guides on the Makera Instructables Page, YouTube Channel, and Wiki Page.

Thanks for reading, and happy making!

Written by @MrErdreich and @Makera_Inc