The Veritas dividing rule makes it easy to divide boards into halves, thirds, quarters, all the way up to tenths — it works on boards eight inches wide and smaller. Change the orientation and it also functions as a marking gauge.
Veritas makes the rule from stainless steel and the pins from brass. The pins swivel and have a flat side for keeping the rule in the right position. Markings on the top of the pins show you when the flat sides are fully seated against the board’s edge.
To divide a board, twist the rule on the board so the pin on the pointed end and one of the pins on the flat end seat against the board edges. Pick the correct hole, place a pencil into it, and run the rule the length of the board. Repeat as necessary.
To use it as a marking gauge and mark lines up to four inches away from the edge, seat the two pins on the flat side of the gauge against the board edge and place your pencil into the second set of holes spaced every 1/16″. Since the pins swivel, you can also use the marking gauge for curved edges, but the scale will be slightly inaccurate.