When I made the double side fence for the router table and the table saw (you can see it here) I had not too much experience with the router table. After some time I realized that the vertical insert I put on the fence in the side of the router table is too thin, and it gives slightly when I want to route the head of the wood strips. The problem is that the routing I make is crooked (it doesn’t happen when routing lengthwise). That’s why I decided to install a split fence with an adjustable opening behind the router bit.
And while it sounds like a complicated thing to do, I found it to be a fairly simple upgrade to my home router table.
To make this adjustable split fence, which upgrades my router table fence, I used a strip of plywood about 20 millimeters thick that I had in the workshop. To attach this new split fence to the side one piece fence that I already have on the router table, I use bolts with washers and wing nuts that allow me to tighten or loosen the parts of the split fence to easily adjust it to the desired position.
In order to use these nuts I needed a T-slot, so first I routed a slot wider than the diameter of the washers. And that slot must be slightly deeper than the height of the bolt head plus the washers.
With the new split fence against the one piece fence of the router table, I decide the height at which I want to put the bolts. And I mark the width of the slot with the help of one of the washers. I adjust the router table fence to route a first slot adjusted to one of the marks, and finish the total thickness of the slot by making a second pass on the router table. Now I can glue a 10 mm thick piece of plywood on it.
I cut a piece of the same width on the homemade table saw (the one I made with a hand-held circular saw) and glue it on the face with the slot. I try to apply a thin layer of glue so that it does not enter the slot. I also avoid fitting the long sides of both pieces of plywood, as I prefer to leave the long sides offset a couple of millimeters and trim them later with the table saw. This way, both pieces of plywood are perfectly flush in both edges.
Once the glue is dry, I mark the diameter of the clamping bolts on the 10mm piece of plywood, I adjust the cutting height of the table saw, and finish making the T-slot in two passes on the saw.
I mark the area where I want to cut the split fence in two and divide it by making a V-cut on the miter saw.
Now I only have to drill the holes in the old fence for the clamping bolts of the new split fence, and I install the two parts of the split fence by putting the hex head of the bolts and the washer into the T-slot. Although I had originally planned to use two washers with each bolt inside the T-slot, I finally used only one so that the parts of the split fence slide sideways without any problems. And despite the fact that nothing but friction blocks the hex head of the bolts from turning when tightening the wing nuts, the wing nuts tighten smoothly.
Now I can adjust the opening depending on the router bit I need to use. And if I “mess up” the split fence with the router bits, I can always re-cut the ends of the split fence in V, since I left the parts of the split fence several centimeters longer than the original fence to each side of the router table. Surely now I can make perfect routings in the head of the wood strips, for example to make tenons, but first I want to make a woodworking jig to keep the wooden strips and boards perfect at 90º with the router table fence while routing.