An excerpt from the Spring 2007 issue of Woodworking Magazine, available on the newsstands now.
My boss, Steve Shanesy, held up a dial caliper to make his point about precision woodworking. “If you can work to 1″, then you can work to 11?64″, or to .005″ or to whatever,” he said. “Those are all just arbitrary numbers, and you can work to any of them.”
I allowed Steve’s admonition to become ingrained in my heart and hands that day. I bought a dial caliper. And for years I used that caliper as my sixth sense in the shop and experienced every aspect of my joinery through its steel jaws.
In many ways, the caliper pushed me to become a better woodworker. It showed me how closely each of my tenons fit. It pointed out every joinery flaw and forced me to find ways to work that were more precise and repeatable.
But the dial caliper can be a cruel master.
It measures things that are difficult , sometimes impossible , to do anything about. Let’s say your boards come out of the planer and they are .004″ thicker than what you wanted. What do you do? For years I struggled to get a sensitive touch with the adjustment wheels on my heavy machines. I succeeded, but I could never live up to the expectations of my caliper.
Then one day I was at a woodworking show in Canada and there was an old-timer there who was selling old folding rulers. They were beautiful things with brass corner joints. Some of the scales were made of ivory. Most were boxwood. Naturally, I checked the price tag on one. I don’t remember the price, but I do remember what was scrawled next to it: “French inches.” French inches? What the heck are those?
Before the French invented the metric system (yes, something else to blame the French for) and then formally adopted it in 1799, there were competing systems of measurement that would vary by region. The French pouce (inch) was a little shorter than the inch we use today, about 7 percent shorter.
Until that moment, in my mind there were only the metric and imperial systems. The idea that there were other ways to measure things in the world of furniture was confusing. And so I began to realize that all measurement systems are arbitrary. I eyed my caliper warily and wondered if life might be better if I switched to the metric system, where I could divide anything by 10.
But, as it turned out, archaic measurement systems aren’t arbitrary. As I read more, I discovered the Japanese shaku, an archaic unit of measurement still used today by temple carpenters. The shaku, developed independently of our system, is 11.93″ long. The ancient Egyptian foot measures 12.25″. And many of the measurements that eventually evolved into the imperial system were based on the human body, such as the cubit , the distance between an average-sized man’s finger and elbow.
And because our furniture is supposed to fit our bodies, it makes sense that our measurement systems should spring from there.
But what about the ancients and their way of working? Would they mock the caliper? Well, it turns out that tiny units are nothing new, either. The Indus Valley civilization (2,600 B.C.) had measurement units that were less than .07″. So while we desire to have our measurement systems reflect our bodies, we also need to quantify , measure , anything we can see or feel. Hence, the caliper.
In the end, I’ve concluded that for me, calipers are like another important ancient invention: beer. Both must be used sparingly , or I’ll never get anything done.
I always shoot for tight-fitting joints instead of hitting an arbitrary number on a caliper. I strive for beauty to the eye rather than on-the-nose tenon lengths.
But how do you get there? How do you teach yourself to make furniture without someone looking over your shoulder at the critical first stages of learning the craft? You need an unyielding master who can point out the things you haven’t yet trained your eye to see. You need a master you can someday outgrow or even exceed.
In the modern home workshop that master just might be a dial caliper.
– Christopher Schwarz
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