Wood is a diverse material. You have hardwood, softwood, and sheets like plywood and MDF board. And so, the cutting tool must be equally capable of performing the task.
A CNC router bit is a tool installed onto the CNC router to perform a wide range of activities, such as cutting, carving, or engraving. When it comes to wood, the CNC router machine that you use must also be fitted with an appropriate router. Here is an exhaustive guide on CNC router bits, right from their many kinds to how to choose one according to your project.
Let’s get started.
CNC Router Bit Tip Shapes
Based on the tip shape, most CNC router bits can be classified as:
- Flat-bottom bits: Also known as cylindrical router bits or surfacing bits, these are mainly used for surface milling. However, if you happen to pick one with cutting flutes on the sides, you can use this edge to carve into wood.
- V-groove bits: These cut in the V-shape. The angular separation determines the nature of the cut. For instance, 90-degrees will make wider marks while 30 or 60-degrees will leave sharp edges.
- Ball nose tips: Also known as round nose bits, they are highly versatile tools that can be used for cutting, engraving, and finishing products.
- Tapered ball nose tips: These are a variation of ball nose tips as the tapering ends with a rounded tip. These are used for projection carving, relief carving, and more.
- Corn teeth end mills: These bits have teeth on the side edges and are often used to cut hardwood. The abrasive action of these teeth helps the milling machine in cutting through the material.
- Drill bits: As the name indicates, drill bits are used for drilling holes into the workpieces.
- 3D router bits: Such router bits are used by CNC vertical mill for forming special designs and reliefs. Quite often, they are tapered router end mills having a significant taper angle at the cutting tip.
CNC Router Bit Materials
CNC Router bits are commonly composed of the following materials:
- High-Speed Steel (HSS): These enjoy high heat resistance, hardness, and wear-and-tear resistance.
- Solid Carbide: These are wear-resistant and sturdy and use varying forms of carbide that determine its toughness.
- Carbide-Tipped: Rather than making an entire router bit of carbide, the cutting edge or tip has carbide brazed onto the core steel body.
- Solid Tungsten Carbide: These use tungsten carbide particles bound to metallic cobalt, which combine strength with durability.
- Polycrystalline Diamond (PCD): PCD bits use diamond particles that are sintered with a binder of carbide substrate for an extremely hard and abrasive-resistant bit.
Choosing the CNC Router Bit for Wood: A Quick Guide
Now that you have a holistic understanding of the different bits used by CNC machines, you can make the smarter choice by factoring in the following considerations:
- Router Function: CNC router bits are broadly classified as milling or drilling tools based on their actions. The former performs the engraving action, while the latter is for pre-drilling holes for screws and fasteners.
- Material Compatibility: The hardness of the material determines the type of CNC router bit that one uses. Hardwood, for instance, will require high-speed stainless steel bits. In contrast, softwood can be worked on using regular carbide bits.
- Shaft Diameter: Ensure that the shaft diameter of the bit fits in the collet of the router. Failure to do so will render the bit useless.
- Cutting Length: Knowing the cutting length will allow the desired finishing. For example, while cutting for ¾ inch thick stock, a cutting length of 1 inch offers sufficient room for a clean cut.
- Cutting Diameter: If a bit has a quarter-inch diameter shank, it doesn’t necessarily mean that it will cut a clean quarter-inch diameter. One can have bits with a quarter-inch shank but ⅛ inch cutting diameter. Hence, pay close attention to the cutting diameter.
- Tip Radius: For router bits that are not cylindrical, you will have to consider the tip radius, which is the curvature of the bottom cutting edge to the center of the bit.
- Overall Length: Overall length is the total length of the bit. Ideally, it should reach down right into the material and go as deep as the project requires.
- Storage: Just as much as they need to be used carefully, CNC router bits also have to be stored carefully. For instance, certain materials, such as carbide, are brittle and can shatter on getting knocked on by other pieces of carbide.
CNC routers bits are available in varying shapes and sizes, each of them having a defined purpose. As a result, the bit you choose will significantly influence the durability, outcome, and finishing. Apart from delivering excellent results, they will also impact the process and the longevity of the tool and CNC machine. Simply put, this choice will have a great bearing on the entire project, so choose wisely.
About the Author: Peter Jacobs
Peter Jacobs is the Senior Director of Marketing at CNC Masters. He is actively involved in manufacturing processes and regularly contributes his insights to various blogs on CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general.