All-weather runners for a tablesaw sled
I live in a climate where the humidity varies a lot, causing wood to expand and contract considerably. As a result, my tablesaw's crosscut sled, made from MDF, would often hang up in the miter slots as I tried to push it through. To solve the problem, I created the adjustable runners shown here so I can have a snug, but smooth-running, operation regardless of the weather.
To add these expandable miter runners to one of your sleds, begin by cutting runners that are 1⁄16 " shallower and narrower than your miter slots. Next, attach some cloth-backed double-faced tape to the top of the runners and center them in the miter slots. Lay some pennies in the bottom of the slot so the runners will be proud of the surface, and shim the sides to keep them centered. Expose the tape and lay your jig squarely on the runners to temporarily position them.
Remove the jig (with runners attached), and drill and countersink pilot holes through each runner and into the jig. Mark the runners so you can attach them exactly as you drilled them, and then remove the runners and tape. Use a jigsaw to cut the 1" expansion slots shown in the drawing. Now, install 1/4-20x1⁄2 " threaded inserts into the jig bottom at each pilot-hole location, and attach the runners to the sled with the flathead machine screws. Tightening the screws causes the runner to spread slightly until it fits perfectly in your tool's miter slot.
I check the fit each time I use my crosscut sled and adjust the width of the runners as needed. To further reduce friction, I occasionally wax the runners and the bottom of the sled.
—Larry Plagens, Conroe, Texas