Router Bits Guide: How to Choose and Use Them

Looking for the right router bit for wood? In this guide, we will introduce the main types of bits and advise you on how to choose the right one.

Do you groove, trim, profile, or simply work with wood? Router bits are an essential part of your woodworking tool arsenal. You probably already know that. However, you might not be sure whether you need brazed router bits, bits with reversible knives, spiral bits, or even diamond bits. Nevertheless, an inappropriately chosen bit can lead to poor finish, as well as rapid wear of the tool itself. That’s why it is important to pay proper attention to selecting the right router bit.

Router bits can be used in routers, spindle moulders or CNC routers. They differ in their construction, material and use. Selecting the right one is crucial for the quality of the resulting product. However, each type has a different purpose. Not every bit is suitable for use in a router. Some may be designed for router tables or spindle moulders. Therefore, always follow the manufacturer’s recommendations for each specific bit.

Router Bits Are Perfect for DIYers as Well as Professionals

Based on their construction and the way cutting edges are fitted, router bits for wood can be divided into four basic types:

Router cutters with brazed tips – steel bits with a carbide cutting edge permanently brazed to the body of the bit
Router cutters with reversible knives – bits with replaceable knives that can be rotated or changed when blunt
Spiral router bits – made from a single piece of carbide with milled spiral cutting edges
Diamond router bits – extra hard bits with teeth made of polycrystalline (synthetic) diamond

The most commonly used bits have shanks with a diameter of 6, 8, or 12 millimetres. These can be found in practically every woodworking shop. There are also bits with a wider shank, designed for demanding use in industrial environments and mass production.

To learn how to properly rout with router bits to achieve the highest quality results while maintaining the long-term durability of your tool, we highly recommend reading the article The Best Cutting Conditions for Woodworking. This article is especially useful for those who are just starting with routing and woodworking.

Basic Types of Router Bits – Differences in Construction and Application

As we have already mentioned, different types of router bits with shank vary in construction, placement and teeth hardness. These factors determine how they should be used and which types of materials they are best suited for. Belowfind a comprehensive overview of router bit types, along with their characteristic, description of their construction, and a list of suitable or unsuitable materials and tasks for which they can be used.

Brazed Router Bits by IGM and CMT

Brazed router bits for wood from renowned brands IGM and CMT are known for their solid bodies made of premium steel and carbide cutting edges that are 2 mm thick, allowing them to be resharpened more than ten times. The body of the tool is coated with Teflon: red for IGM and orange for CMT.

The Teflon coating protects the cutter from corrosion, prevents dust and adhesives from sticking to the body, and reduces friction. It also acts as a thermal shield, a crucial feature. When the tool overheats during operation, it dulls quicker and needs to be resharpened more often. You would hardly find a Teflon coating on low-cost and low-quality router bits, which is one of the reasons why tools from hobby markets have significantly shorter lifespan compared to premium bits.

Instead of a Teflon coating, low-cost router bits are often coated with a regular paint, which disappears immediately due to the heat generated during routing. In addition to surface treatment, they also differ in the quality of the materials used. Their bodies are usually made of ordinary carbon steel, and the carbide teeth are less than half the thickness, leading to poor cut and very rapid dulling.

In terms of versatility, brazed router bits are unmatched. There are countless types and shapes of bits, from grooving and rabbeting to dovetail and decorative profile bits. If you find it difficult to choose the right one, don’t miss our article 5 Main Router Bits for Everyday Tasks.

Features of Brazed Cutters by IGM and CMT:

2 mm thick carbide cutting edges
Can be resharpened more than 10 times
Protective Teflon coating
A wide variety of types for creating grooves, rabbets, joints, engraving, edge routing, template trimming, and more
Suitable for machining of solid wood, chipboard, plywood, plastics
Less suitable for MDF and Laminate – dulls more quickly

Router Cutters with Reversible Knives

Router bits with replaceable knives are perfect for professional woodworkers, who don’t want to waste time with sharpening. The knives typically have 2 to 4 cutting edges, so it is possible to rotate them up to three times when blunt. At IGM, we have been developing the router cutters with replaceable knives since 2000. From the beginning, we have focused on using premium-quality knives made of high-strength and tough stainless steel. Thanks to this, they offer long-lasting performance and unmatched cutting quality.

The use of these cutters is essentially the same as brazed bits. However, it is necessary to choose the right hardness of the knives based on the material. Softer knives are more suitable for solid wood or plywood as they are more flexible, less prone to breaking, and ideal for heterogenous materials. On the other hand, harder knives are excellent for machining laminate, MDF boards, and other homogenous material because they do not dull as easily and stay sharp for longer.

The only disadvantage of the router bits with reversible knives is the knife attachment system. Due to the size of screws and wedges, they are not available in very small diameters. These cutters are only available starting from a diameter of 8 mm. However, this is compensated by their durability, quality, and a wide range of applications that is unmatched on today’s market.

Features of IGM cutters with replaceable knives:

The knives can be rotated or replaced with new ones when they become dull
Available starting from a diameter of 8 mm
Since the knives are not sharpened, the routing diameter does not change
They have versatile application, similar to brazed cutters
Depending on the hardness of the knives, all types of materials can be routed

Spiral Router Bits

Spiral router bits are characterized by the fact that they do not have a steel body but are entirely made of carbide with two, three, or four spirals milled into them. This makes them more expensive but also more fragile than brazed bits. On the other hand, their construction allows for much better balance and precision.

The direction of the spiral flute divides spiral router bits into upcut, downcut, and up & downcut types.

Upcut flute design (same direction of tool rotation) guides chips upward towards the collet, providing clean finish at the bottom edge of the material. Upcut spiral bits are ideal for deeper grooves.
Downcut flute design (opposite direction of tool rotation) pushes chips and sawdust downwards, providing clean ginish at the top edge of the material.
up & downcut spiral bits combine both flute directions: upcut at the bottom and downcut at the top. This provides clean cut at both the top and bottom edge of the material, which is useful for trimming and formatting workpieces.

For more information about the differences between up and downcut design of spiral cutters, watch the video below.

In addition to up-, down-, and up & downcut spiral cutters, there are also roughing bits with serrated cutting edges that allow for deeper material removal and chip breaking for easier cleanup. After using the roughing bit, the surface of the workpiece remains serrated, making them unsuitable for products where aesthetics is important. In such cases, it is necessary to use a finishing bit to smooth the surface.

Features of spiral cutters:

Made from a single piece of carbide with 2 to 4 milled spiral flutes – the more spirals, the higher the cutting performance and the faster the cut
Divided into upcut, downcut, and up & downcut types. Each type has a different purpose and method of use
Highly precise with a long lifespan
Handy for formatting, grooving, edging, and 3D routing
Suitable for solid wood, chipboard, laminate, plastics, and non-ferrous metals

Diamond Router bits

Diamond (DIA) router bits are among the most powerful tools you can insert in your router’s collet. DIA cutters are almost exclusively used in industrial machining on CNC machines—not only due to their extremely high cost. However, artificial diamond tip is up to 50 times more resistant to dulling compared to carbide, making them an excellent choice for industrial furniture production, CNC machining, and any application where long tool life is crucial without the need for frequent and time-consuming replacements. They are particularly useful in mass production, where time is a key factor in the manufacturing process.

The teeth of this type of router bit are made of artificial polycrystalline diamond, with a thickness ranging from 1.6 to 2 mm for economical bits and 3 to 4 mm for professional bits. Economical bits are more affordable, but due to the thinness of their teeth, sharpening is not an option. Professional bits, on the other hand, can be sharpened in the usual way, but their price ranges in thousands of Euros.

Features of diamond router bits:

Steel body with a carbide tooth fitted with a thin polycrystalline diamond tip
Economical version with a 1,6–2 mm tip and a professional version with a 3 – 4 mm tip
Both variants are suitable for industrial production and CNC centres
Ideal for trimming and grooving
Perfect for machining large-surface materials – laminate, MDF, chipboard, compact and veneered boards

To choose a router bit best suited for your specific project, take a look at the table below.

Type of Bit	Suitable Materials	Unsuitable Materials	Applications
Brazed Router Bit	Solid wood, plywood, plastics	MDF, laminate (dulls quickly)	Grooves, pockets, joinery, rabbets, engravings, rounding
Router Bit with Replaceable Knives (hard knives)	Laminate, MDF boards	Solid wood	Universal use depending on the type of bit
Router Bit with Replaceable Knives (soft knives)	Solid wood	Laminate, MDF boards	Universal use depending on the type of bit
Spiral Router Bit	Solid wood, plywood, non-ferrous metals, plastics	Laminate	Grooving, formatting, CNC machining
Diamond Router Bit	Large-surface materials – laminate, MDF, chipboards, compact and veneered boards, Corian, composites	Solid wood	Grooving, formatting

Accessories for Router Bits

Finally, we must not forget about router bit accessories, which can be extremely useful in your workshop. Available accessories include collet reducers, bearings with limiting rings, clamping chucks, and even a practical router bit stand.

The longevity of your router bits begins with proper care. A cleaning emulsion for woodworking tools significantly extends the lifespan of router bits by reducing friction and excessive heat buildup. This prevents the bit from dulling quickly and reduces the need for frequent sharpening. Cleaning off dirt and residue with a cleaning emulsion takes only a few moments, but it greatly extends the life of your tool. And that’s a pretty good reason to have one in your workshop.

Do you already know which router bit type is the right one for you? Have a look at our offer and choose the best cutter for your woodworking project.