Step 1: Learn About the Jig

The jig starts as a 16" piece of 2" x 2". Dowels are spaced in different locations on the board. The spacing of the dowels allows the use of the same jig to find the center of a 2" board, a 4" board, a 6" board, and a 12" board. A hole in the center of the jig holds a pencil so the center of the board can be marked once the jig locates it.

Step 2: Mark the Measurements

Use a tape measure to find and mark 8" from one end of the piece of 2" x 2". This is the center of the jig. Make marks in the same spot on each face of the board.

On one face of the jig, make a mark 1-1/4" on either side of the center mark. This will be the face for finding the center of a 2" board.

On another face of the jig, make marks 2-1/4" on either side of the center mark. This is the face for 4" material.

On the third face, make marks 3-1/4" on either side of the board. This face will be for centering 6" material.

On the last face of the jig, make marks 6-1/4" on either side of the center mark. This is the face that will be used for 12" material.

Step 3: Drill the Holes

Use a 3/8" drill bit on a drill press to drill holes in each of the locations marked on the board, except for the center marks. It is not necessary to drill all the way through the jig.

Use a smaller diameter bit to drill a hole for the pencil hole over the center mark. Drill this hole all the way through the material.

Pound in 3/8" dowels into the 3/8" holes.

Step 4: Use the Jig

To use the jig, place the appropriate face over the board being centered and place the pencil in its hole. Turn the jig so that the dowels fit snugly against the board. Then, push the jig across the board, allowing the pencil to draw a line down the center of the board.