In this quick technique post – Edge Jointing With A Router – I wanted to explain how you can use a router with a simple straight bit, and a bushing for your router base, and get the same results you can get with a large edge jointer.
In addition to these tools, you’ll also need a good board to use as a straight edge. 1/2″ or 3/4″ thick works great here. I prefer using sheet material as it needs to be wide enough so once it’s all clamped, you still have room for half your router base to ride on.
I’ll be using some store-bought shelving material I had laying around, which still had a good factory edge on.
Before starting, check that the straight edge is really straight. Use something like a long steel rule.
Why do we need to edge joint?
Because when gluing up a panel, or anything that’s getting glued edge to edge and needs to remain flat, the edge of the board needs to be perfectly flat, and square to the face.
Each board within the panel, on each side, should be this way.
So we run our boards, ideally, thru an edge jointer to square it up and make it flat.
This is really to fix any flaw left in the edge after it has ran thru the table saw.
And while the table saw gets the edge really close to perfect, and in many cases it is good enough, sometimes it needs just a little jointing to finish up.
Especially if your table saw isn’t tuned really well.
Another issue we run into is if the board’s straight edge from the lumber store isn’t straight to begin with, it’s hard to fix that with a table saw.
And that too is where jointing comes into play.
So if you’re lacking a good edge jointer, but you have a router, you can produce the same results right on your work bench.
Here’s an overview diagram of this method:
Now, just follow the steps here, and refer to my pictures and the diagram above for illustration.
1 – Insert your straight cut bit into the router, and a guide-bushing in the router base plate. Take note of the spacing between the edge of the bit, and the outer edge of the bushing.
2 – Lay the board to be jointed (work piece) on your bench, with none of the bench directly underneath the actual edge getting jointed.
3 – Lay the straight edge board on top of the work piece. This board will need to be longer than the work piece.
4 – Take the distance you figured in step 1, add 1/16″ and this is how much of the work piece needs to be exposed from underneath the straight edge. For me, my bushing edge is 1/8″ from the blade on the bit, so I offset my straight edge 3/16″ from the edge of my work piece. This allows for 1/16″ removal during the jointing.
5 – Now clamp both side, both the work piece and the straight edge, down to the work bench.
6 – Make sure there are no spots of the work pieces edge that are not exposed at least 1/16″ from underneath the straight edge. You can scribble lines along the work piece edge, so when complete you can make sure all the lines are gone.
7 – Now turn on your router and run it down the board, letting the guide bushing run along the straight edge. This will leave an edge square to the board face, and as flat as the straight edge you used.