Magnets and metal lend a helping hand in a pinch
Engineers and welders have long known about a wonderful little tool—the magnetic base. Unlike other magnets, these bases are magnetic only when you turn them on. Although typically used with swivel-arm clamps and dial indicators, they also work well by themselves all around the shop, for example to hold a workpiece against a fence like a feather board, as shown. Once activated, they will stick to your cast-iron table or any other ferrous surface almost like they're bolted in place.
—Warren Perkins Jr., Millington, Mich.