Every good bench vise deserves a dog
To attach a dog for straight edge clamping, drill three 3⁄8 " holes in the top of the movable jaw's wooden face. Keep the holes somewhat close to the metal jaw in order not to weaken the wooden face. Using dowel centers, transfer the hole locations to a removable vise dog made of 3⁄4 x3⁄4 " hardwood, and drill three matching holes. Glue three dowels or metal rods into the removable dog, and it will be ready to pop into place when you need it. The dog's long face spreads pressure over a wide area and reduces the chance of marring the workpiece.
To clamp small, irregular, or round workpieces, drill two similar holes in the stationary face, as shown, and then place a combination of dowels into any of the five jaw holes for holding those pieces. When the dogs are not in use, tape over the holes to keep sawdust from falling inside.
—Frank Penicka, Mount Pearl, Newfoundland