The longer I’m a woodworker, the less I like systems of measurement. Whether you’re a machinist who works in metric, an imperious advocate of imperial, or a Bob who measures in “bobs,” there is one thing that is true about all these systems: They invite error.
When you add, subtract, multiply or divide these measurements, you are doomed to make a mistake. We transpose numbers. We “burn an inch” when we use a tape measure by reading on the wrong side of the line. And we simply back ourselves into a difficult corner when we need to divide the face of a board into five equal spaces with 1/8″ between each space.
The solution, for me, is to reject measuring systems and rely instead on two things:
1. Direct readings. (Put the door stile up to the door opening. Mark the length of the stile. Make the cut.)
2. A lot of dividers.