Selecting an appropriate router bit for your Computerized Numerical Control (CNC) project is crucial as it determines the kind of carving you can accomplish, the resolution of your finished design, and how fast you can move through the material. Essentially, choosing the right router bit determines the success of your CNC router projects.
Finding suitable router bits, though essential, can be challenging as today’s market is flooded with so many different kinds. We’ve devised a comprehensive selection guide to help you choose the best router bit for your CNC projects.
Router bits are classified under two major categories based on their primary function. These are:
- Drill Bits: These router bits drive straight down into the material. They do not have side edges, which means they cannot move laterally while boring into the material. Because of this function, they are best used for jobs that require material to be removed straight down, such as in pre-drilling holes for screws.
- Milling Bits: These are also known as carving or engraving router bits. They are designed for movement across the surface of a material and are used for clearing away chips as they move in order to create 3D designs.
Router bits can come in a variety of materials, which directly impact their quality. Choosing the right type of material can determine the kind of materials that you can work with and affect the overall cost of your CNC projects.
The most common materials include:
- Low-Carbon Steel: The cheapest option among all router bits due to their poor tempers. Although they are tough, they are relatively softer and weaker than other materials and are used to drill softwood and some plastics.
- High-Speed Steel (HSS): HSS router bits have high heat and wear resistance and are famed for their hardness. They are much better than low-carbon steel bits and are recommended for cutting foams. Although they are more expensive than their low-carbon counterparts, they are built to last.
- Solid Carbide (SC): SC bits are among the most popular for CNC router projects because they are sturdy and wear-resistant. They are made by mixing carbide with other metals such as tungsten or titanium. In some instances, especially since carbide is expensive, steel CNC router bits can come with a solid carbide tip to mix the longevity of carbide with the affordability of a steel core.
Router bits can also be classified based on the shape of their tips, with each having specific functions. The basic types include:
- Straight End: Also called flat bottom bits, the shape of these cutting tools are cylindrical while their cutting end is flat. They can be used for engraving using the side edges. The flat end, meanwhile, makes it easy to cut horizontal surfaces.
- Ball Nose: The cutting edge on ball nose bits have an arc shape and can form a hemisphere when used. They can cut smoothly and are especially suitable for semi-finish and engraving curved surfaces.
- V Bit: These are typically used when the project calls for V-shaped cuts in the material. The angle of the V-bit can vary, depending on the angle required in the design. Thanks to their sharp edges and small tips, they can be used for fine engraving work.
Spiral bits are among the most common router bits used in CNC router projects. They are great for general usage and have a variety of applications, depending on their cut direction.
- Up Cut: Up cutting involves pulling chips upward as cuts are made. This is preferable if you want to clear chips the further you cut through the material to prevent overheating.
- Down Cut: In down cutting, bits are pressed back into the material as cuts are made. This shearing action is excellent when you want to preserve the top surface of the material. It leaves a clean cut at the top of the material but may fray the bottom edge, making it unsuitable for drilling holes.
- Compression: Compression bits have a combination of up and down bits, offering benefits of both and eliminating chipping. This makes it ideal for cutting materials like plywood since the top is pushed down while the bottom is pulled up, making for a clean edge on both sides.
Number of Flutes
Flutes are sharp slots found on router bits responsible for cutting and providing a path for ejected chips. Fewer flutes give more space to clear chips and get through the material more quickly, which is ideal for softer materials like wood (2 flutes). However, more flutes are recommended for more rigid materials like steel and acrylic (6 to 8 flutes). They are also better for CNC projects that require small corners and fine details.
Other Important Considerations
There are other important considerations to make when selecting suitable CNC router bits for your CNC router projects. Major considerations include:
- Project Suitability – more detailed work calls for router bits with fine tips such as V-bits.
- Material Compatibility – certain materials call for different applications. For instance, plastic requires bits that won’t melt it during cutting.
- Cut Length – always go for the shortest cutting length to avoid deflection, vibration, and an inferior finish during cutting.
- Cut Diameter – use the largest tool diameter possible for longer tool life and a quality finish.
- Bit Sharpness – the sharper a bit is, the more easily it can cut the material. There are instances where it’s better and more affordable to buy a new bit than to sharpen it. It’s advisable not to attempt to sharpen bits by yourself.
Finally, speed and finish should be balanced. Choose a bit that helps you accomplish your targets. A bit that can get through the material quickly tends to produce large chips, which increases the likelihood of your router breaking. Meanwhile, bits that produce a smoother finish will go through material more slowly and can dull your bits. It’s all about striking a good balance.
Choose CAMaster for Your CNC Router Projects
CAMaster is committed to supplying you with knowledgeable advice to help you use your CNC router more successfully in a wide range of applications. As a leading supplier of top-quality CNC machines, we provide technical support and service to help you succeed in your industry. Get in touch with us today to learn more about our industry-leading products.