Build a Mitre Crosscut Sled
If you often cut mitres on large sheet goods, you might want to make this jig even larger, but I have found it comfortable for parts up to 20″ wide by almost any length. I made this sled for a right-tilt tablesaw. For a left-tilt saw, you might want to adjust the build so the sled runs to the right of the blade. Though it’s not necessary, I would recommend doing so, as the work-piece’s finished surface will be on top during the cut, and the resulting mitred edge and corner will be cleaner.
When you require repetitive cuts at a certain length, the extension arm is screwed into place. It should be either flush with the fence or slightly inset so that it doesn’t interfere with anything.
With the extension arm secured, the stop block can be fixed to it with a small clamp. You can even clamp the stop block directly to the fence if your work-pieces are short enough.
Runner, base and fence
Start by machining the runner from a strip of straight-grained, quarter-sawn hardwood. The runner should slide in the mitre gauge track on your tablesaw with absolutely no slop. Cut the 1/2″ Baltic birch base to size. The flatter the base, the better.
Insert the runner in your mitre gauge slot and place the base on the surface of your tablesaw so the right end of the base extends slightly beyond the angled blade. Any overhang will eventually be cut off. You can also bring your rip fence over to help position the base and hold it in place if need be. Attach the base to the runner from above or below, and then make the first pass with the blade angled at 45° to trim the excess base.
Machine the fence slightly longer than your base is wide, and from straight-grained hardwood. Machine a 3/4″ wide x 3/4″ deep groove in it, on your tablesaw or router table. The groove should be approximately centered on the fence’s face and be about 12″ long. With the fence roughly flush with the back edge of the base, drive a single screw through the base into the fence. The fence should overhang the base’s mitred edge slightly, as it will eventually be cut off. With a carpenter’s square (that is square!) adjust the fence to form a right angle with the freshly mitred edge of the base and add another screw. Make a test cut and check for square. Once you’re satisfied, add a few more screws to secure the fence to the base. Just be sure not to drill oversized screw clearance holes or the fit will be sloppy.
Extension arm and stop block
Make the extension arm so it fits inside the groove nicely. Adjust its length depending on your requirements. A couple of screws fix it to the fence when it’s required. Use a strong hardwood for the extension arm. Soft wood will flex once the stop block and clamp are attached to it. Make a stop block that can be clamped to the extension arm. Ensure the stop block extends down to the top surface of the base. The stop block can be clamped to the fence or extension arm for repeated cuts.
Break all sharp edges, apply a coat of wax to the runner, and drill a hole in the base so you can hang it on the wall. Don’t apply a coat of finish to the sled, as I find it only reduces friction between the sled and the workpiece.