To the Irish a "jig" is a traditional folk dance. To a woodworker it's a guide for drilling holes. It is especially handy for repetitive drilling that requires precise spacing such as for pegs that support movable shelves that go up and down in cabinets and bookcases. Rather than doing tedious measuring and marking, try this: When you're faced with drilling lots of equally spaced holes such as for shelving, skip the tape measure and grab a piece of peg board. Then using its factory-drilled holes as a template and guide, drill away as you would with an expensive store-bought gadget. Your holes will be equally spaced and true. That's how we Careys do our quickie jig for shelves. And that's the On The House tip for today.