Reinventing nails: increasing efficiency via technological finesse

nailSometimes the efficiency of resource use can be increased through technological that uses understanding to improve technological finesse. The redesign of the nail appears to be a great example of this situation. PopSci picked a new nail as its innovation of 2006. Research on nails has lead to better nail designs which has produced nails that hold things together much better, but that are not much more costly to manufacture. From PopSci’s Best of What’s New 2006

Hurricane winds rip apart nailed-together walls, and earthquakes shake houses so violently that a nailhead can pull straight through a piece of plywood. Since we can’t stop natural disasters, Bostitch engineer Ed Sutt has dedicated his career to designing a better nail. The result is the HurriQuake, and it has the perfect combination of features to withstand nature’s darker moods. The bottom section is circled with angled barbs that resist pulling out in wind gusts up to 170 mph. This “ring shank” stops halfway up to leave the middle of the nail, which endures the most punishment during an earthquake, at its maximum thickness and strength. The blade-like facets of the nail’s twisted top—the spiral shank—keep planks from wobbling, which weakens a joint. And the HurriQuake’s head is 25 percent larger than average to better resist counter-sinking and pulling through. The best part: It costs only about $15 more to build a house using HurriQuakes. $45 per 4,000;

Although there are no precise statistics, Sutt’s research indicated that nail failure accounted for a substantial percentage of the destruction in these catastrophes. And when nails fail, it’s for one of three reasons. Either the nail rips its head through the sheathing, its shank pulls out of the frame, or its midsection snaps under the lateral loads that rock a house during high winds and earthquakes. Sutt’s job was to design a nail that resisted all three. “With the first prototypes,” Sutt says, “we proved that a bigger head has substantial advantages in terms of stopping the nail from pulling through the sheathing. But it couldn’t be too big, because it needed to fit into popular nail guns.”As the Bostitch team tweaked the head-to-shank ratio, Sutt and metallurgist Tom Stall worked on optimizing high-carbon alloys, trying to find the highest-strength trade-off between stiffness and pliability—the key to preventing snapped nails. “Meanwhile,” Sutt says, “we were focusing on how to keep the nail from pulling out.” The team machined a series of barbed rings that extend up the nail’s shaft from its point, experimenting with the size and placement of the barbs. “You want the rings to have maximum holding power,” he says, “but if they go up too high, it creates a more brittle shank that shears more easily.”

The team tested hundreds of designs, looking for the best compromises. The late prototypes held fast, and Bostitch came out with a barbed nail with a larger head in 2005 called the Sheather Plus. But the solutions created problems of their own: As the barbs pierced the sheathing, they generated a hole that was slightly bigger than the shank, resulting in a loose, sloppy joint.

“We needed a way to lock the top of the shank into the sheathing,” says Sutt, who attacked the problem in a series of brainstorming sessions with his engineers. Their solution: a screw-shank, a slight twist at the top of the shaft that locks the nail in place. The combination of the screw-shank, barbed rings, fatter head, and high-strength alloy added up to an elegant solution to the failures that had plagued nails for more than two centuries. Sutt’s team had, in effect, reinvented the nail.

Before I leave Clemson, I ask Schiff if he sees any downside to his protege’s invention. “Homeowners and insurance companies are going to love these nails,” he says. “But contractors are going to hate them, because when they make mistakes, it’s not a trivial thing to remove them. Once you nail something together, it’s going to stay together.

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