Build a simple table saw sled to make perfectly square cross cuts in both small and wide boards. You only need a 4x4 sheet of 1/2-in. plywood and a few hours time.
By the DIY experts of The Family Handyman Magazine:March 2011
If you own a table saw, you know it works great for ripping long pieces. But did you know that you can crosscut wide pieces with the same ease and accuracy? All it takes is a table saw sled. A table saw sled rides in the miter gauge slots and has a fence that's mounted exactly 90 degrees to the blade, enabling accurate square cuts. We'll show you how to build a sled using a 42-in. square sheet of 1/2-in. plywood.
We used top-quality nine-ply birch, but any flat plywood with smooth faces will work. The tricky parts of the construction are cutting runners that slide smoothly in the tracks, and getting the fence perfectly square to the blade. We'll show you how to accomplish both as you construct the sled.
Start by cutting strips of plywood for the stiffener, front fence and blade cover (Figure A). Cut them 1/4 in. wider and 1/2 in. longer than the finished size to allow for trimming. Then spread wood glue on the mating faces and clamp them together. Clamp them onto a perfectly flat surface like the top of your table saw. Try to keep the layers lined up as you clamp them. After about 20 minutes, scrape off the partially hardened glue. Then run the pieces through the table saw, removing about 1/4 in. Using Figure A as a guide, mark the shapes onto the pieces and saw them out with a jigsaw. Smooth the curves with a belt sander.
Technical art by Mario Ferro
For part names and dimensions, see the Cutting List in “Additional Information” below.
Figure A, the Cutting List and a complete Materials List are available in pdf format in “Additional Information” below.
Figure B is available in pdf format in “Additional Information” below.
You must remove the blade guard on your table saw to use the sled. To prevent accidents:
Slide a hardwood board in the miter gauge slot on your table saw to check the fit. If it's too tight, sand and plane it until it slides easily with no slop. Work on this while you're waiting for the glue to set up on the fence blank (about a half hour).
Rest the runners on pennies to elevate the top edge above the surface of the saw. Apply a thin bead of wood glue down the center of the top of the runners.
Glue the base to the runner, using the table saw fence to position it. Make sure the edge farthest from the fence overhangs the table saw at least 2 in. Set weights on the base until the glue dries.
Sand the edges of the runners where they rub on the sides of the miter gauge slots. Dark spots indicate areas that need sanding.
The next step is to cut the runners from strips of hardwood. If you have standard 3/4-in.-wide miter gauge slots, sand or plane a 1x3 hardwood board until it slides easily in the slots (Photo 1). (For narrower slots, you'll have to plane or cut the 1x3 to reduce its thickness.) Then rip strips from the 1x3 that are about 1/16 in. thinner than the depth of the slot. Photos 2 and 3 show how to attach the strips to the sled base. Let the glue set for about 20 minutes. Then remove the assembly from the table saw and scrape off excess glue from the edges of the runners and bottom of the base. You'll also have to clean out any glue that has gotten into the slots on the table saw. Slide the sled back and forth in the slots. If the sled doesn't slide easily, inspect the runners for darkened areas where the metal has rubbed on the wood. Use spray adhesive to attach a piece of 80-grit sandpaper to a square-edged block of wood and sand the darkened areas to remove a little wood (Photo 4). Repeat this process until the sled slides freely.
Square the fence with the blade. Raise the blade and press a framing square against it. Swivel the fence on a single screw in one end, and clamp the opposite end when the fence is square to the blade.
Clamp one end until you check the fence for square (next step).
Glue and screw the stiffener to the front edge of the base, being careful to keep screws away from the path of the table saw blade. Then set the table saw blade to about 3/4 in. high and slide the base into the blade. Stop cutting when you get within 3 in. of the back of the base. Turn off the saw and let it come to a stop before removing the sled. Align the fence with the back edge of the base and drive a screw into the right end. Photo 5 shows how to square the fence to the saw blade and clamp it in place. Screw the blade cover to the back of the fence, being careful to keep the screws well away from the path of the blade.
Check the position of the fence by cutting a scrap of plywood. Flip one side over and butt the two pieces together. A gap means the fence isn't square.
With the clamp firmly in place, set a 12-in. or wider scrap of plywood on the sled and cut it in two. Test the accuracy of the
sled by flipping one side of the cut scrap over and pushing the freshly cut edge against the other half (Photo 6). If the two pieces fit perfectly with no gap, the sled is cutting squarely and you can drive three additional screws into the fence to hold it in place. Otherwise, tap the clamped end of the fence with a hammer to nudge the fence a bit. Then make another test cut. Repeat this process until the cut is perfect. Then add the screws.
Install stops to prevent the blade from cutting through the blade cover.
Complete the sled by adding the stop blocks. With the blade half covered by the fence and blade cover, screw a block to the bottom of the sled. Use carriage bolts to attach another stop block to the table saw bed (Photo 7).
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.
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