Microadjustable sled enables perfect 90° crosscuts
Starting with a typical crosscut-sled design, add a fence glued up from two layers of 3⁄4 " plywood, as shown in the drawing. (Using plywood in lieu of solid lumber makes it more resistant to seasonal humidity changes.)
Next, clamp the fence to the crossmember and drill a hole for a 5⁄16 "-18 threaded rod through the crossmember, just into the fence. Unclamp the two pieces, drill the fence hole deeper, and install a 5⁄16 "-18 threaded insert in that hole. Clamp the fence to the base as squarely as possible; then drill a hole through the fence top for the pivot and a hole in the center of the slot where the fence locking assembly will insert. Remove the fence and drill the rest of the fence locking assembly slot. Insert a screw through the pivot hole, topping it with a washer and nut. Slide a 5⁄16 "-18 threaded rod through the crossmember, slip on a 3⁄8 " OD compression spring, and thread the rod into the insert. To complete the sled, install a fine adjustment knob on the threaded rod and a fence-locking knob atop the fence locking assembly.
To use, simply loosen the knob on the fence and twist the fine adjustment knob to pivot the fence.
—Bill Wells, Olympia, Wash.