I seldom use a portable sander. I prefer to plane my stock smooth, then complete the polishing process by hand sanding with a cork-soled sanding block. I use this simple jig to get the most efficient use from full sheets of sandpaper.
Two different fences (cut from the same piece of wood) position a full sheet of sandpaper so it can be torn into six identically sized smaller pieces. As demonstrated in the photos at right, the jig allows this to be done quickly and accurately.
Two Fences Turn Three into Six
To make this simple jig, first cut the base from scrap plywood. Next, create the two offset wooden fences. One is used for the first tear-off of paper, the other for the second tear. Glue them to the long edge of the base as shown in the Drawings. The two spacers are made of cardboard (often called chipboard) that you find on a pad of notebook paper.
The cardboard’s thickness holds the hacksaw blade off the base so you can slide the sandpaper underneath and up against the appropriate fence. Mount the blade 31-1⁄16" away from the “first tear” fence with two screws driven through the blade holes. Face the toothed edge out.
Use the first fence to divide the sheet across its width into three equal pieces, then abut these strips against the second fence to tear each of them into two equivalent 4-1⁄2"-long pieces.
Simple yet effective, this jig is an asset to my shop, and I am confident it will be to yours, too.