Forstner bits work great in a drill press, but how can you ensure a perpendicular hole in the middle of a large workpiece or built-in cabinet?

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Bore Perpendicular

Forstner bits work great in a drill press, but how can you ensure a perpendicular hole in the middle of a large workpiece or built-in cabinet? Here's how to make a jig that gives you flat-bottomed holes with a portable drill.

As shown above, attach a piece of 14 " hardboard to one face of a block of wood that has been jointed perfectly square. Chuck the Forstner bit for the desired hole into your drill press. Bore into the face of the block opposite the hardboard piece until the bit just contacts the hardboard, leaving a centered dimple. With that dimple as a center, drill through the hardboard with a bit the same diameter as the Forstner bit's shank.

Next, remove the hardboard guide and clamp the jig where you want the hole in your workpiece. Place the Forstner bit into the hole in the block, slip the hardboard guide over the shank, and reattach it to the block. Finally, chuck the bit shank into your portable drill and bore a perfectly perpendicular hole.
—Myron Backhaus, Pleasant Hill, Calif.