Creating joinery with a router

Learning how to fasten wood together is critical to almost any wood working project you take on. Today I will go over some of the more common types of wood joints and how to create them using a basic wood working router and some bits.

There are many different types of joinery that a wood worker can use to join two or more pieces of wood together.  Depending on the situation and the amount of stress a joint will be subjected to a wood worker needs to create a joint that will be able to with stand the stress.

Selecting a joint that is going to maximize strength is important. This is determined by the amount of glue surface of the joint and the direction of any stresses the joint will experience.

Housed Dado
Used when making book shelves or other frames a housed dado is the most common joint. It is simply a flat bottomed groove in a piece of stock.

Using a wood router and a straight cutting bit a housed dado can be easily cut. The easiest way is to clamp a straight edge to your stock to guide the router. With your wood router unplugged measure the diameter of the base plate and take note of the bit diameter. Use the radius of the base plate minus the radius of the bit to determine how far from your layout marks you will need to clamp the straight edge.

Once your straight edge is clamped in the proper position simply guide your router through the cut. Take several passes, increasing the depth of the cut with each pass. This way you are able to control the router easier and reduce the work load on the router. Continue to cut and reposition your straight edge until you have cut all the dados.

Stopped Dado
Ideal for shelves or bookcases that don't have a face frame a stopped dado hides the joint to make a project look better. Stopped dados are created the same way you would make a housed dado. Great for shelves and bookcases without face frames a stopped dado allows a woodworker to hide the joint along the front edge. This still provides the strength of the dado joint but stops just short of the front edge.

To make a stopped dado simply mark the joint about an inch from the front edge and stop the router as you get to that mark.

Rabbet Joint
A rabbet joint is simple a groove or dado that is cut along the edge of a piece of stock. The simplest way to form a rabbet joint is to use a rabetting bit in your router. This is a straight cutting bit whose depth of cut is controlled by a guide bearing. Depending on the size of the rabbet you can change the size of the guide bearing.

Rabbets are used mostly along the back edge of a piece of stock to make a recess for a plywood back. They are also ideal for making a recess in a frame for a mirror or piece of glass.

Tongue & Groove Joint
Basically a tongue on one piece of stock that fits into a groove on a mating piece of stock. There is plenty of glue surface area making a tongue and groove a very strong joint.

Creating a tongue and groove joint is a bit more work then a housed dado but is still rather simple with a router table. First start by cutting the groove. A general rule of thumb is to cut the groove first and cut the tongue to fit. The groove should be 50% of the thickness of your stock.

Start at the router table and fit your router with a straight cutting bit. Adjust the rip fence until it is as close to center as you can get it. Set the height of the router bit so it is about 1/16" deeper then you need. Now simply feed the stock through the bit taking extra care to keep the wood tight to the fence and down on the table.

To get the groove exactly centered run the wood through the router again but this time flip the stock so the opposite face is against the fence.

Now measure the width of the groove and set the height of the bit to half that value. Feed the mating piece of wood through the router, making a pass on both sides to get a tongue that is perfectly centered.

The four types of joints described above will be used most often in day to day wood working. They will likely make up the majority of simple joints that you make. With all the joints above gluing and clamping the stock together will create a joint stronger the surrounding wood and make for very stable projects.