Unfolding the history of carpenter’s the rule
Look at the tools of any master craftsman, and you’re likely to find one. Maybe it’s made out of Boxwood, worn but still straight and true. Maybe it’s made out of metal, wearing a patina earned with age and use. Maybe it’s an older piece, made out of bone or ivory, passed down for generations.
Whatever it’s made of, the carpenter’s rule, also known as the folding rule or mason’s rule, has a long and revered history in the world of woodworking and craftsmanship. The tool gets its name from the fact that it folds down to a fraction of its full size—generally six to eight inches when folded—and rules of this kind can be traced back for centuries.
Rules have been around since antiquity, and began as an attempt to standardize the way we measure objects or distances by using anatomical benchmarks like the length of a foot or the span of a hand. This evolved over time, and by the 17th century, rules were generally segmented into inches, with smaller increments being added later.
The practice of creating folding rules stemmed from the need for portable and compact equipment; a folded carpenter’s rule could be carried on person, and to this day, carpenters’ overalls are made with a pocket specifically designed to fit a folded rule.
While folding rules have a very long history, they had their manufacturing heyday from the early-19th century to the mid-20th century. In modern times carpenter’s rules are often replaced with a tape measure, but they are still made—and used—today.
The long and short of it
Carpenter’s rules were manufactured not only with a range of materials, but with diversity of design. They generally measure one or two feet fully extended. Some had calipers at the end, or were made of wood but edged in brass to protect from warping. Most rules had either one, two or four folds created by joints made from brass or an alloy known as German silver.
The joints were often round, double arch joints, chosen for their strength and durability. This is attested to by one of the oldest known folding rules—made of brass, it was found in the ruins of Pompeii, having survived the volcanic explosion that destroyed the city.
While many of these rules are seen now as collectors’ items commanding a high price on eBay and at antique auctions, for artisans they are what they have always been: time-honored and useful tools in carrying out the craft they love with skill and precision.