Introduction to CNC Router Bits for Beginners: Types, Sizes, and How to Choose

For Beginners: An Introduction to CNC Router Bits—Types, Sizes, and How to Choose

Choosing CNC router bits affects machining precision, finish, machining time, and tool life. For beginners, it is important to understand the tools that are right for the material, shape, and machining method.

Flat end mills are widely used for contouring and pocket machining, while ball end mills are used for3D carving and machining curved surfaces. V-bits are suitable for machining letters and decorative grooves, while face milling bits are ideal for flattening the sacrificial board used with a CNC machine.

This article explains the most commontypes and uses of CNC router bits, how to choose the right size, and what to check before machining. We also introduce three types of LUNYEE bit sets designed for different applications.

1. Main Types and Uses of CNC Router Bits

CNC router bits are suited for different machining tasks depending on their blade shape. Understanding these differences will make it easier to choose the right tool for your project.

Flat End Mills

A flat end mill is a tool with a flat tip that iswidely used in CNC machining. Its main applications include contouring, slotting, pocket machining with a flat bottom, and material removal.

For example, when making a wooden nameplate, it can be used to cut out the outer perimeter or machine recesses. Smaller tools are suitable for narrow slots and small interior corners, while larger tools are ideal for efficiently removing material over a wide area.

 

Flat end mills also come in types that eject chips in different directions.

l Up-cut end mill: Ejects chips upward, helping to clear chips from deep slots and pockets. However, it may cause chipping or fraying on the top edge of the workpiece.

l Down-cut end mill: Pushes chips downward, making it easier to achieve a clean finish on the top edge of sheet materials such as plywood. However, it may be difficult to eject chips during particularly deep cuts.

l Compression end mill: Combines up-cut and down-cut blades. When the depth of cut and material thickness are appropriate, it can reduce chipping and fraying on both the top and bottom surfaces of the sheet material.

 

Choose the blade type based on the material, depth of cut, chip ejection requirements, and desired edge finish. Because small tools can bend or break under excessive force, you must also manage the cutting load.

Ball End Mills

A ball end mill is a tool with a spherical tip that issuitable for 3D carving, relief carving, machining curved surfaces, and finishing.

When carving a wooden relief, a flat end mill can remove most of the material, after which a ball end mill can finish the details of the curved surfaces. Smaller tools make it easier to reproduce intricate shapes, while larger tools canmachine a wide area in a single pass.

Ball end mills are not very efficient for machining wide, flat bottoms. The finish also depends on the stepover, which is the distance between adjacent tool paths. Generally, a smaller stepover produces a smoother surface but increases machining time.

 

V-Bits and Carving Bits

A V-bit is a tool with angled blades that is widely used for lettering, sign making, decorative lines, and V-groove machining.

The angle of the cutting edge determines the shape of the groove. At the same depth of cut, a V-bit with a smaller angle generally produces a narrower groove, while one with a larger angle produces a wider groove.

For example, you can engrave a name into a wooden sign or add decorative lines to a panel. Changing the depth of cut also changes the width of the groove, allowing you to machine lines of different thicknesses with the same tool.

Carving bits are used for small letters, fine markings, and precision work. Many have pointed or V-shaped tips. Carving bits and V-bits are not entirely separate types; their uses and shapes overlap.

When choosing a carving bit, check the cutting edge angle, tip shape, and minimum cutting width. Thin cutting edges are useful for fine machining but may be more susceptible to damage.

Chamfer Bits

A chamfer bit is a tool that creates a beveled edge on the workpiece. It is used to remove sharp corners, chamfer edges, and achieve a uniform edge finish.

For example, chamfering the edges of a cut wooden panel can give it a finished appearance.

Both chamfer bits andV-bits machine angled surfaces, but their main uses differ. Chamfer bits are primarily used for finishing edges, while V-bits are used for letters, grooves, and decorative carving.

 

Face Milling Bits

A face milling bit is a tool for removing material over a relatively wide area.It can be used to flatten the sacrificial board used with a CNC machine or to level the surface of a workpiece so that it is suitable for machining.

If the sacrificial board has uneven surfaces, using a suitable face milling bit to lightly machine the surface can create a more uniform reference surface for subsequent machining.

Before use, check that the bit's diameter, shank, and operating conditions are compatible with the machine. Because larger tools require higher spindle power and machine rigidity, not all desktopCNC routers can efficiently use every type of face milling bit.

 

Drills and Small End Mills

A drill is primarily a tool for making holes by cutting in the axial direction. A small end mill is used for narrow slots, fine contours, and intricate shapes.

For example, you can use a suitable drill for mounting holes in a wooden panel and a small end mill to create narrow slots around complex shapes.

The difference between the two is clear when machining printed circuit boards (PCBs). A drill makes holes in the board, while an insulation milling bit removes copper between conductive patterns. For insulation milling, you can use a suitable V-bit or small tool depending on the pattern spacing, copper thickness, board flatness, and required insulation width.

CNC Router Bit Quick Reference Chart

Tool Type	Main Uses	Typical Machining Examples
Flat End Mill	Contours, slots, and pockets with flat bottoms	Wooden parts and recesses
Ball End Mill	Curved surfaces and3D contours	Relief carving and 3D shapes
V-Bit	Letters andV-grooves	Signs and decorative carving
Chamfer Bit	Beveled edges and chamfers	Panel and corner finishing
Face Milling Bit	Flattening the sacrificial board
Drill	Axial hole drilling	Mounting holes and specified hole machining
Small End Mill	Narrow slots and fine contours	Intricate machining and compatible board milling

These categories overlap. For example, even though an end mill may be suitable for multiple materials, the blade shape and machining conditions must be matched to the machining task.

 

2. Choosing the RightCNC Router Bit for Your Project

First, clarify the machining task, material, and desired finish.

Choose Based on the Machining Task

Use the following table as a guide for choosing tools.

Project / Machining Task	Recommended Tool
Contouring and slotting	Flat end mill
Pocket machining with a flat bottom	Flat end mill
3D relief and curved surface machining	Ball end mill
Lettering andV-groove machining	V-bit
Edge chamfering	Chamfer bit
Flattening the sacrificial board	Face milling bit compatible with the machine
Mounting hole drilling	Suitable drill
Insulation milling of boards	SuitableV-bit or small tool

These are guidelines, not rules that apply to every situation. The final choice also depends on the material, machine capabilities, tool dimensions, and machining conditions.

Choose Based on the Material

Tools suitable for wood may not be suitable for plastic, aluminum, or PCB materials. Tool material, blade shape, chip evacuation, and machining conditions affect the finish.

Wood: Flat end mills are suitable for contours and pockets, while ball end mills are suitable for relief carving. Depending on chip evacuation and edge finish, you can choose upcut, downcut, or compression types.

Plastic: Choose tools suitable for the resin you are machining. If excessive heat softens the material, chips may stick to the blade edge, resulting in a poor finish. Proper spindle speed, feed rate, and chip evacuation are important.

Aluminum: Use tools and machining methods suitable for machining non-ferrous metals. Tool engagement, chip evacuation, depth of cut, and machine rigidity must be carefully managed. Not all woodworking bits or desktopCNC configurations are suitable for aluminum machining. Follow the tool manufacturer's recommended conditions and check whether the machine can handle the intended machining.

PCB materials: Use PCB tools suitable for non-conductive machining and drilling. Small-diameter tools are suitable for fine shapes, but when machining thin copper foil, the flatness of the PCB and the thickness of the copper foil are particularly important. Cuts that are too deep can damage the PCB, while cuts that are too shallow may leave copper between the patterns, causing them to remain connected.

Consider detail reproduction, finish, and material removal

Tool diameter affects the smallest shape that can be machined and the amount of material that can be removed ina single pass.

Small-diameter tools can reach narrow grooves and small internal corners, but they are generally more prone to breaking and may require more passes. Larger-diameter tools are efficient for wider cuts, but they cannot machine details smaller than the dimensions reproducible by the tool shape.

For complex projects, it may be more effective to use different tools for rough and finishing machining than to usea single tool for everything. One method is to remove most of the material with a flat end mill and finish the curved surfaces of the relief with a ball end mill.

The number of teeth also affects machining characteristics.Two-tooth bits are commonly used in CNC routers, but the number of teeth alone does not determine performance. The best choice depends on the material, tool shape, space for chips, spindle speed, and feed rate. More teeth do not necessarily result in a better finish or faster machining.

 

3. How to Read CNC Router Bit Size Notations

Before mounting, check the shank diameter, blade diameter, blade length, and overall length. These dimensions help determine whether the tool can be mounted on the machine and whether it can handle the intended machining.

Shank Diameter

The shank is the axis part of the tool that is secured with a collet. The shank diameter must fit the corresponding collet and spindle system.

Common sizes include1/8 inch (3.175 mm) and 1/4 inch (6.35 mm). They cannot be directly replaced without the appropriate collet or an approved tool-holding configuration.

For example,a 1/4-inch shank cannot be directly secured in a 1/8-inch collet. Always check the collet size and compatibility before mounting.

Blade Diameter

Blade diameter determines the nominal cutting width of the tool. It affects the smallest groove width and internal shape that can be machined, as well as material removal efficiency.

Small-diameter end mills are suitable for small letters and fine contours, while larger-diameter tools are generally suitable for efficiently machining wide pockets and contours. Actual results also depend on the toolpath shape, tool deflection, and machine accuracy.

Blade Length and Overall Length

Blade length is the length of the cutting part, while overall length is the length from one end of the tool to the other.

The blade length must accommodate the required machining depth. However, longer is not necessarily better. If the tool is extended too far, the risk of deflection, vibration, and breakage increases.

Before choosing a long tool, check the available range of motion of the machine, the required machining depth, and the recommended tool engagement.

Number of Teeth

Tools have cutting edges and grooves for chip evacuation. Their number and shape affect the space for chips, machining characteristics, and finish.

Two-tooth bits are used in many CNC router applications. Single-tooth bits may provide more space for chips and are effective for some plastics and non-ferrous metals. Multi-tooth tools may be suitable for other materials or conditions, but they provide less space for chips.

There is no single optimal number of teeth for all applications. Choose based on the material, tool diameter, spindle speed, feed rate, and chip evacuation conditions.

 

 

4. LUNYEE CNC Router Bit Sets Selectable by Application

The tools required vary depending on the CNC project. LUNYEE offers bit sets for general routing, fine machining, and decorative woodworking.

1. LUNYEE 1/4-Inch Shank CNC Router Bit Basic Kit

Set contents:30° V-bit, two spiral end mills, flattening bit, chamfering bit, and ER11 collet for 1/4-inch shanks.

Recommended applications and users: A basic set of tools for letters, grooves, flattening, and edge finishing, ideal for beginners and hobby users.

This practical set combines multiple tools used in everyday CNC router machining and is ideal for starting various woodworking projects.

2. LUNYEE 40-Piece End Mill Set with ER11 and ER16 Collets

Set contents: Flat end mills and ball end mills with different blade diameters. Includes coated tools and ER11 and ER16 collets.

Recommended applications and users: For grooves, pockets, detailing, and 3D carving, ideal for those who need end mills with a wide range of blade diameters.

Using multiple blade diameters allows for flexibility from rough machining to fine detailing. Before use, check the compatibility of the machine spindle and collet.

3. LUNYEE 10-Piece 1/4-Inch Shank CNC Router Bit Set

Recommended applications and users: Letter carving, sign making, V-groove machining, trimming, and decorative detailing for DIY enthusiasts and woodworking hobby users.

This solid carbide tool set is designed for various woodworking and routing applications. Check the shape and specifications of each tool to ensure the set includes the tools required for your intended machining.

Which Set to Choose

l Basic Kit: Consider this if you want a set of tools for general CNC router machining, including carving, flattening, and chamfering.

l End Mill40-Piece Set: Suitable when multiple blade diameters and both flat and ball types are needed for fine machining.

l Router Bit10-Piece Set: Consider this if you want to use it for decorative woodworking or general routing.

Before choosing, check the tool type, shank diameter, collet compatibility, and compatible materials for each tool. If many tools do not suit your application, a larger set is not necessarily the best choice.

 

Summary

Choosing CNC router bits begins with understanding the machining, material, and required level of detail. Flat end mills are suitable for contours and pockets, ball end mills for curved surfaces, and V-bits for letters and grooves, while flattening and drilling each use dedicated tools.

Before working, check the tool shape, shank diameter, blade length, and compatibility with the machine. By choosing the appropriate tool and machining conditions, even beginners can more easily achieve a consistent finish and acquire CNC machining skills while reducing unnecessary tool wear.