Edge Joint on a Router Table

If you own a router table, you have what it takes to create perfect edges for glue up. And thanks to carbide cutters, a router table can joint the edges of abrasive man-made materials like MDF and particleboard, something that can’t be done on most jointers (those with steel knives) without ruining the cutters.

Woodworkers quickly learn that a table saw does not leave an edge that’s ready for gluing. Saw marks and slight irregularities from hand feeding the stock add up to unsightly glue lines. That’s when a woodworker’s desire turns to jointers. But what if a jointer has yet to make its way off the wish list and into the shop? Take heart, there is hope for the jointer-less. It’s your router table to the rescue.

Photo 1. A simple shop-made fence is all you need to edge joint on a router table. Glue a strip of plastic laminate on the out feed side of the fence to act as an offset. The thickness of the laminate determines the amount of material removed in each pass.

Photo 2. Some commercial fences include shim stock to create an offset on the out feed fence. Shims allow you to adjust the depth of cut taken on each pass.

All you need to edge joint on your router table is a fence with an offset in it, and a carbide straight bit. (Photos 1 and 2)

There are a number of suitable carbide straight cutters for jointing on the router table. In general, use the shortest, stockiest bit possible. Tall skinny bits are more prone to chatter. Large diameter bits work best because their greater mass and higher rim speed help them produce a smoother cut. Be sure to use a 1/2″ shank for stock over 3/8″ thick. Long straight cutters can be used to joint stock over 2″ thick. A sharp bit and a slow feed rate will reduce the risk of chatter with these bits. My favorite bit for jointing is a 1/2″ diameter spiral cutter. It gives the best results in stock under 1-1/4″ thick. These bits aren’t cheap, but they produce an amazingly smooth edge with little or no tear-out, even on squirrely-grained woods. For a little less money, you can pick up a 1-1/2″ diameter straight cutter that also does a nice job. Even a regular straight bit will work.

Photo 3. With the router unplugged, use a square and a 1/2

To set up your router table for jointing, first make sure the bit and your router table are perpendicular to each other. (Photo 3)

Photo 4. Set the fence so the out feed half is even with the cutting edge of the bit. First, eyeball the fence and clamp one end. The hold a straight edge against the out feed side and swing the fence until the straight edge contacts the cutter. (see inset) The cutter should just kiss the straight edge.

Photo 4 Inset. Swing the fence until the straight edge contacts the cutter.

Once the bit and table are square, it’s time to set the fence. (Photo 4) Get the fence as close as you can to being correctly positioned, but don’t sweat it too much. A test cut will very quickly tell you if you need to tweak the settings. The fence is correctly set when the board stays in perfect contact with both the infeed and outfeed side of the fence throughout the cut.

Photo 5. Make a test cut. Snipe at the end of the cut indicates that you're removing too much material. Adjust the fence to remove less material and take another cut. If the stock bumps into the out feed fence, then the cut is too shallow.

Next, make a test cut, and adjust the fence as needed. (Photo 5)

Photo 6. Mark the joint with a triangle that points away from you. This will help you keep track of the face side of each board and which edge to joint.

To prep your stock for edge jointing, start by marking the joint. (Photo 6)

Photo 7. A slow and steady feed rate works best. Keel the stock tight against the fence throughout the cut. For the best fitting joint, feed on board face down and the next board face up.

Once your stock is marked, you can joint the mating edges. (Photo 7) A trick I learned early in my woodworking days, is to joint one board face down and the next face up. (Or if you’re using a jointer, keep the face of one board against the fence and the next away from it.) This helps compensate for a cut that’s less than perfectly square and will produce edges that are a perfect mirror image to each other.

Photo 8. The result is a perfect joint that's easy to assemble and invisible to the eye.

Good edges lead to a good glue up.
(Photo Eight) Boards properly jointed and glued create a seam that’s stronger than the surrounding material, and virtually invisible.

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