Strong, precise joinery is the hallmark of quality woodworking. It's the hidden architecture that gives furniture its strength and longevity. While traditional hand-tool methods have their place, a modern router equipped with the correct Router Cutters can produce exceptionally strong and accurate joints with speed and repeatability. From simple grooves for shelving to classic tongue and groove panelling, the router is a joinery powerhouse.
As a brand founded by tradespeople, Key Blades & Fixings knows that the right tool is critical for a successful outcome. Our professional-grade Router Cutters are engineered for the precision that joinery demands. This guide will provide a detailed tutorial on how to cut several essential woodworking joints using your router, explaining cutter selection and providing step-by-step instructions.
The Foundation of Router Joinery: Grooves and Dadoes
Grooves and dadoes are the simplest yet most fundamental joints you can make with a router. They form the basis for everything from bookcases to cabinet construction.
- A dado is a square-bottomed channel cut across the grain of a workpiece.
- A groove is the same type of channel cut parallel to the grain.
How to Cut Perfect Dadoes for Shelving
A dado joint provides robust, three-sided support for shelves, making it far superior to simple screws or nails.
Cutter Selection:
The ideal tool is a high-quality Straight Router Cutter. For the tightest fit, the diameter of your cutter should precisely match the thickness of your shelf material. For example, to fit a 18mm thick shelf, use an 18mm straight bit. If you don't have the exact size, you can use a smaller bit and make two parallel passes.
Step-by-Step Instructions:
- Mark Your Layout: Carefully measure and mark the centreline for each shelf on your upright panels. Use a combination square to ensure your lines are perfectly perpendicular to the edge of the panel.
- Set Up a Guide: The key to a straight dado is a reliable guide. Clamp a straightedge or a track saw guide to your workpiece. The distance from your marked line to the edge of the guide must equal the distance from the edge of your router's baseplate to the edge of the cutting bit.
- Set the Cutting Depth: For strong support without compromising the panel's integrity, set the router's plunge depth to approximately one-third of the panel's thickness. For an 18mm panel, a 6mm deep dado is ideal.
- Make the Cut: Place your router firmly against the straightedge guide. To avoid tear-out and burning, make the cut in two or three shallow passes rather than one deep one. Move the router at a steady pace to get a clean channel.
- Test the Fit: After cutting, slide a piece of your shelf material into the dado. It should be a snug fit, tight enough to hold but not so tight that you need a mallet to force it in.
Creating Strong Edges: The Rabbet Joint
A rabbet (or rebate) is an L-shaped recess cut along the edge of a board. It is incredibly versatile and commonly used for recessing cabinet backs, creating shiplap, and forming simple but strong corner joints for boxes.
How to Cut a Rabbet Joint
There are two primary methods for cutting a rabbet with a router.
Cutter Selection:
- Method 1: Rabbeting Cutter. This is a specialised bit with a bearing guide. They often come in sets with interchangeable bearings of different diameters, allowing you to easily change the width of the rabbet. This is the fastest and easiest method.
- Method 2: Straight Router Cutter. You can also use a standard Straight Router Cutter in conjunction with your router's edge guide or a router table fence.
Step-by-Step Instructions (Using a Rabbeting Cutter):
- Select the Bearing: Choose the bearing that corresponds to the width of the rabbet you need. The smaller the bearing, the wider the cut will be.
- Set the Depth: Adjust the router's depth to control how deep the rabbet is cut into the board's face.
- Rout the Edge: With the workpiece securely clamped, run the router along the edge. Keep the bearing in constant contact with the edge of the board to ensure a consistent cut width. As with dadoes, make deeper rabbets in multiple passes.
Panelling and Flooring: The Tongue and Groove Joint
The tongue and groove joint is a classic method for joining boards edge-to-edge to create wide, flat, and strong panels. It's used for everything from solid wood flooring and wall cladding to tabletops and door panels. The interlocking profile prevents the boards from shifting and helps keep the surface flat.
How to Cut Tongue and Groove Joints
This joint is most efficiently and accurately cut on a router table.
Cutter Selection:
You will need a matched set of Tongue and Groove Router Cutters. One cutter is designed to cut the slot (the groove), and the other is designed to cut the corresponding projection (the tongue). These are often sold as a set.
Step-by-Step Instructions:
- Cut the Groove First: Install the grooving bit into your router table. Adjust the bit height so the groove will be perfectly centred on the thickness of your board. You can test this by making a cut on a piece of scrap, flipping it over, and making another pass. If the two cuts align perfectly, your height is correct. Run one edge of all your boards through to cut the groove.
- Set Up for the Tongue: Switch to the tongue-cutting bit. To set the height, take one of the boards you just grooved and use it as a reference. Adjust the tongue bit's height until the profile aligns perfectly with the groove.
- Cut the Tongue: Run the opposite edge of each board over the tongue-cutting bit. The tongue should now fit snugly into the groove of the adjacent board, creating a seamless joint.
Other Essential Router Joints
Beyond these core joints, your router can create many other forms of joinery.
The Mortise and Tenon (Router-Assisted)
While complex, a router can make cutting the mortise (the socket) for a mortise and tenon joint incredibly fast and accurate.
- Cutter: A Straight Router Cutter or an up-spiral bit to help with chip extraction.
- Method: Use a plunge router and a jig (either commercial or shop-made) to guide the cuts. Carefully mark out the mortise and rout the waste material in several deep passes. The tenon can then be cut on a table saw or with a router and jig.
The Finger Joint
Finger joints provide a huge amount of gluing surface area, creating an incredibly strong corner joint.
- Cutter: A specialised Finger Joint Router Cutter.
- Method: This joint requires extreme precision and is best made using a router table and a well-made jig to ensure the "fingers" are spaced perfectly.
By mastering these joinery techniques, you can elevate the quality and durability of your woodworking projects. The key to success lies in careful layout, the use of guides and jigs for accuracy, and investing in high-quality, sharp Router Cutters. With a little practice, your router will become your most trusted partner for creating joinery you can be proud of.