Tablesaw extension and router table
Last update: May 24, 2011

It took over a year to complete this project, but it's finally done. This page is sort of a diary of how I built this custom extension and router table for my SawStop. Next up: outfeed table!

I'm building an extension table for my SawStop tablesaw, based on a torsion box design. I know, many of you will react "that's overkill" but I've never been known for doing things halfway. It'll also incorporate a table-mounted router on the other end, allowing me to flip my Incra fence around and attach the WonderFence for routing.

The core uses ribs and stringers made of ¾" birch plywood connected using mortise-and-tenon joints made with my Festool Domino. I used two simple jigs, one to mortise the small cross-ribs and one to do the main stringers. The first really doesn't qualify as a jig, just a piece of ¾" plywood clamped to the tablesaw. I just set the rib and Domino against it and cut the mortise. Since I knew I'd be putting the tenons back-to-back in the interior stringers, leaving the tenons more exposed than normal, I cut the tenons extra-deep. The Domino's depth control made this super easy.

The second jig was a bit more complex, but not much so. Just two bits of plywood slightly overlapped to form a "tunnel" for the stringers to slide through. The Domino nestles into the notch of the upper part. The stringer is marked with offsets from the real position of the mortises so that when the mark is aligned with the back of the jig, the Domino's bit is aligned with the "real" position.

After all the internal parts were milled and mortised, I glued tenons in all the stringer mortises. In the photo, you can see the stringers set up for gluing. The near-side has two 2x4s screwed together and milled straight to act a caul for clamping.

All parts dry-fitted, noting the assembly pattern (some parts will be "trapped" and have to be inserted in the proper order). I found a few glue squeeze-outs that were preventing the ribs from seating fully, a quick touchup with a chisel fixed that!

Glue-up complete, ready to start skinning. The aluminum angle is to support the front edge of the router plate. I could have used another plywood rib, but that would have blocked access to the router somewhat. After these photos were taken, I had to reverse the angle in the other direction to ensure clearance for the router base.

Before skinning the frame, we need to make sure the frame is square. First, I screwed together two 2x4s and jointed the edge straight, then clamped it to the table to act as a caul. Then I measured the diagonals of the table and found they were 3/32" out. I put a cleat at one end of the long diagonal (by the caul) and two cleats at the other end. This locked the table into place, then I was able to slide a shim in between the cleat and table edge, pushing the frame into perfect square.

With the frame square, I marked the skin with a grid showing the position of the internal members to give me guides for nailing. This was especially important around the router box, no point in nailing into nothing! Since this side won't get any kind of pressure (hopefully) I'm using 1/4" plywood to make it a bit lighter.

Some glue, a pile of brad nails and we have a complete bottom skin. A couple minutes with a router and that part's all done.

Since this is my last chance to access all the internal areas before skinning the top, I needed to set up a way to attach a replaceable end cap for the router end. I don't want to be running into a sharp laminate edge all the time, so I'm planning to use hardwood. I'll attach it with some recessed cap bolts going into these embedded t-nuts. Since there's no room to swing a hammer, I used a c-clamp to squeeze them into place.

Skinning the top was the same process as the bottom. However, since the top may need to withstand more abuse, I used 1/2" MDF instead.

Next up is to build the router box. It's just a simple box from 3/4" birch ply assembled with dominoes and glue. The front of the cutout is blocked off by a piece of plywood, I cut it out extra large and the box is attached using cleats and screws to allow future changes if need for a different router. Now I need to decide exactly how the ductwork will connect, I'm not sure if it'll be the back or side.

The Incra Wonderfence has a 2.5" dust extraction fitting right on the end of the fence. To take advantage of that, I'm adding a port on the left side of the router box. I'm using a standard 2.5" shop vac hose, I've modified the fitting on one end to turn it into a dust port by clamping it in the lathe and using a parting tool to cut off the last inch or so from the end.

To get a slicker and more durable surface, I'm covering the table with plastic laminate. I chose this granite pattern because I figure it'll hide the inevitable scratches and dings better. Sides first, then the top. If you've never laminated anything, it's pretty simple. First, coat the laminate and the substrate with contact cement according to the manufacturers directions. Let the cement cure for the recommended time, it'll slightly tacky.

Don't let the not-so-sticky feeling fool you, if you accidentally touch the two pieces together getting them apart without tearing up the laminate is nearly impossible. It can be tough aligning the laminate while holding off the substrate, so use wooden stickers to hold the laminate up while you position them. Then start in the middle, removing the sticker and pressing down the laminate with a J-roller. Work your way out, when you get to the end you can hold the edge and curl it while rolling. Keep the last sticker in as long as you can, in case it slips out of your hand. Finally, use the J-roller to apply good pressure over the entire surface, concentrating on the edges. Just be careful around the edge, the roller can ride over the edge and bend/snap the laminate.

On a side note, I've been surprised at this new contact cement I've been using. Its Weldwood Nonflammable. Just as effective as the old stuff, but it doesn't have that awful smell and emits very little VOCs, so you can use it without a mask. The smell still gets a little strong when doing large areas like the table top, but nothing like the old yellow stuff. I also like the way it turns from white to clear when it's ready to be stuck together. Oh, and the brush cleans up with water, too!

Next up was laminating the top. Same process, but with a lot more glue and bigger stickers. After curing overnight, I trimmed the outside edges and inside the router plate opening. One problem that I found and I had feared was the table became non-flat at the router opening, where there's no interior ribs. I was able to use a chisel and break the glue bond, then drive in some very small wedges to lift the top just a hair.

I didn't want to hang the table on the fence rails, at 75 pounds I was afraid it would deflect or twist them. Instead, I used some scrap aluminum bar stock I had around to make two angle brackets and bolted them to the edge of the tablesaw top. They're a bit long so I can use small shims to bring the top up flush with the top. Since there's no way to avoid the bolt head protruding from the side, I used a forstner bit cut small recesses in the end of the table for them. Finally, after tons of work, the table is in place! As you can see, my Harbor Freight hydraulic table comes in handy once again. The extension and table are almost perfectly flush, except where the SawStop falls off a few thousands at the front and back edge.

One amusing bit was the convoluted gizmo I stuck in for some temporary dust collection while routing the recess. Surprisingly, even with a large gap and a wide-open top, it still captured almost all the dust!

In the photos, you can see how my Incra tablesaw fence flips around to act as a router fence. Although I have the Incra WonderFence attached here, you could also make your own sacrificial faces, guides, etc and attach them to the basic fence.

The router box dust collection port is something I've been debating for a while. I finally settled on putting it in the center of the back and integrating a modified version of my shop-made blast gates. The blade is extra long so that I don't have to reach under the table to move it. After taking these photos, however, I decided to go with a short section of flex duct to connect to the main duct instead of hard fittings. Space is rather tight lengthwise under the table and using flex instead of elbows makes for a more compact setup with little loss of airflow. So the green connector bit will be removed and the flex inserted directly instead.

Speaking of airflow, I may have to make some arbitrary openings or some kind of adjustable port in the router box to increase airflow. The pull from the cyclone is tremendous, to the point that I can't pull the door open if the cyclone is running. I'm afraid I'll be starving the cyclone of cooling air.

At this point, I kinda lost track of documenting the final stages of the build, partially because of the constantly changing ideas on how to implement the dust collection. So now we'll just take a look at the final result.

At one point, I really got tired of swapping the Incra fence between the table saw and the router. I thought of installing a second Incra system just for the router, but there just wasn't room. Then I got the bright idea of just installing a fence on the other end of the current bar. This was relatively inexpensive and works really well. I'll go more in-depth on how I did this in another article one day.

Dust collection on the router box works extremely well. Too well, sometimes. When routing a dado, the board can be sucked down so hard that it becomes impossible to move. I've had to resort to blocking the front access door open an inch or two to alleviate some of the suction, I'll have to find a more elegant way to do this in the future. As you can see, I used a standard shop vac hose to connect the box to the Incra fence's dust port. This hose also comes off the fence easily for a convenient way to suck up stray bits that manage to escape during routing. The boxes sides make a handy spot to hang various tools and accessories.

My Triton router lives quite nicely in the box. I removed the power interlock from the router, normally you have to turn it off to raise/lock the collet. The Triton switch is so clumsy, though, that I couldn't stand the thought of having to fight with it on every bit change. Now I can leave it turned on and control the power using the paddle switch on the front. Originally the wires exited from the bottom, but it was pretty simple to disassemble the switch box and reroute the wires out the back and into the router box.