Adjustable miter-gauge extension
If you're like the craftsmen in the WOOD® magazine shop, you usually have a wooden extension attached to your tablesaw miter gauge. An extension gives you control when crosscutting and backs up cuts to prevent grain tearout. Sometimes you'll clamp a stopblock to it for accurate repeat cuts or to control the length of a tenon or lap joint. While most scrap extensions are screwed to the miter gauge and fixed, here's how to make an infinitely adjustable one with router-cut T-slots and a pair of 1⁄4 " toilet-flange bolts. (You'll find these bolts in the plumbing department of hardware stores or home centers.) The extension is so easy to make, you won't hesitate to throw it away when it's used up.
The position of the attachment holes in your miter gauge determines the width of the extension. For a miter gauge with holes close to the bottom, a 3"-wide extension will accommodate two T-slots. For a miter gauge with holes higher up, measure from the bottom of the gauge to the center of the holes, and double this dimension to determine the width of an extension with a single, centered T-slot. A range of 18-24" is a good length. Use solid stock, plywood, or medium-density fiberboard for an extension, and make several at a time so you'll always have a fresh supply.
With your extension stock cut to size, use your tablesaw to cut grooves, where shown in Step 1 of the drawing. Then switch to your table-mounted router, and use a keyhole bit to rout T-slots, where shown in Step 2.
Enlarge the holes in your miter gauge to 17⁄64 ", and fasten the extension to the miter gauge, as shown below. When one end of the extension gets chewed up, loosen the bolts, and slide it off. Flip the extension end for end, slide it back over the bolts, and tighten the nuts, bringing the uncut end of the extension into play, as shown below.