Drill Centering Jig
There are many times when you need to drill holes down the center of a board.
This drill-press jig automatically centers the bit. With some imagination, this
design could also be used to center your piece to a saw blade or a router bit.
The jig is made of two wooden side bars and two metal end pieces. These are joined to form a rectangle that pivots into a parallelogram. The rectangle is elevated above a piece of MDF with washers and joined to it by screws running through the center of the metal ends. A sacrificial backer board is placed underneath the rectangle.
To set up the jig, lower the bit so the tip is trapped between the wooden sides. "Squeeze" the rectangle onto the drill bit and clamp the MDF board to the drill press table. The drill bit will be centered on any piece held by the jig.