Rennie’s Guide to Router Bits

Posted by John Rennie on

Upon first glance, the sheer number of router bit profiles can seem overwhelming, which is why Rennie has come to the rescue with our router bit guide! When considering that a router sits among the most versatile and useful woodworking tools, it’s important to learn all you can about router bits.

With the help of different router bit types, you’ll be able to complete almost any woodworking project. To that end, we’re here to break down the most common router bits and how they’re typically applied.

Choosing the Right Router Bit

The video explains the most widely used router bits, including how to identify them and when to use them. Our router bits may be used in conjunction with all manner of popular branded tools.

What are the different types of router bits?

types of router bits

There are a number of router bit categories to consider when assessing and selecting tool bits. There are 3 commonly used used types of router bits, TCT – tungsten carbide tipped router bits, solid carbide router bits and PCD – polycrystalline diamond. TCT router bits are most commonly used in hand held routers whereas solid carbide router bits are most commonly used in CNC router machines. Detailed below are some of the most common types, as well as the most popular router bit uses.

Flush Trim Router Bits

Flush trim router bits are fairly self-explanatory, as they’re used to cut one material flush’s edge with the edge of the other. Similarly, these bits can be used for the shaping of pattern templates. When it comes to the guiding of these pieces, a pilot bearing with the same diameter as the cutter is typically used. The said bearing may sit at both the bottom and top of the bit, or it could be one or the other. 

Straight Router Bits

Straight Router Bits

Perhaps the most widely used router bits are those with a straight profile. This is because these bits make an incision directly into the material, creating a groove. Typically, this is to form a cavity for an inlay or mortise. Depending on the size requirement, these bits are available in numerous lengths and diameters.

Joinery Router Bits

When you’re in need of a woodworking joint, a joinery router bit is what you’re looking for. Rabbeting router bits are among the most popular types of these, which are steered by a spinning pilot bearing at the tip. The role of these bits is to create a shoulder on the edge of a piece of wood, ready to be joined with another piece. Another popular type is rail-and-stile router bits that create corner joints on doors.

Edge Forming Router Bits

For decorative pieces, it’s all about edge-forming bits. From chamfer to roundover and router bits, each of these creates a unique shape to embellish pieces. Similarly, ogee bits are s-shaped, and there are also variations of router bits that carve half- or quarter-circles. The vast majority of these pieces are guided via a pilot bearing, and they’re most often applied during the decoration stages of woodworking. In this case, edges have often already been trimmed, and these existing edges can act as guides.

Speciality Bits

As the name suggests, speciality router bits are designed to fulfil a specific purpose. From shaping signs to edging doors, there is all manner of router bits to complete these tasks. Speciality bits will range in size, with some being designed for use in router tables and others being crafted for handheld routers. It’s important to use these bits for their intended purpose with the correct tool to ensure safe practice.

Cutting Edges

The vast majority of router bit cutting edges are crafted from carbide or high-speed steel (HSS). CNC router bits are harder than steel, meaning their edge can be held for longer. Despite this, they’re also more brittle. As a result, carbide tips are the preferred choice for handheld routers whereas solid carbide router bits are generally recommended for CNC router machines as they can be ran at much higher feed rates.


The solid, cylindrical section of the router bit is otherwise known as the shank, which slots into the router’s collet. ON TCT tipped router bits the shanks can be found in various sizes; however, the most common are ¼”, ½” and 8mm. Fortunately, a number of handheld routers have interchangeable collets, allowing you to use each size as and when you need to. That said, not every router will have this feature, so it’s important to check the tool before purchasing router bits. On solid carbide router bits, the shank diameter is usually the same as the cutting diameter, so for example a 8mm cutter will have a 8mm shank, a 10mm cutter will have 10mm shank. On smaller sizes on solid carbide router cutters, usually sizes with a cutting diameter of 3mm or under, such as 1mm or 2mm, these are usually supplied on a 1/8” (3.175mm) or ¼” (6.35mm) shank

Indicators of Quality

The overall balance, quality of the carbide, and hardness of the bit are all aspects that can’t be identified just by looking at the bit. Despite this, top-quality carbide cutters are thick enough to facilitate numerous regrindings and have been sharpened to a fine edge. Similarly, the brazing that joins the carbide tips looks even, and the design will reduce the likelihood of workpiece kickback. The body mass of these anti-kickback bits is higher than other bits, and their bodies are significantly larger, too. This helps prevent the bit from cutting too deeply and catching the material. Additionally, it facilitates the dissipation of heat, resulting in sharper bits for longer.

Aside from visible aspects, the price can also determine the quality of a piece. You won’t find suspiciously cheap router bits in the Rennie Range, so you can rest assured that our products are crafted from quality materials.


Are all router bits universal?

Router bits are universal in the sense that they will work with any number of routing tools. What you need to watch out for, though, is the shank diameter. As previously mentioned, the most common diameters are ¼” and ½”, and many routers will accommodate both of these sizes.

What are carbide router bits used for?

Carbide router bits are best used for softwoods, hardwoods, plywood, and some plastics.

Which router bit size is for me?

To learn more specifically about router bit sizes, you can visit our blog explaining router bit sizes. This will help you determine exactly what it is you’re looking for, and you can always pop us an email at if you’re still unsure.

Shop Router Bits at Rennie Tool Company

We hope that this blog has been helpful in differentiating between the different types of router bits. Now, you can browse our range and make your purchases a little more confidently.

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