Ricochet Rangers

A team of four Dartmouth College engineering students think they've discovered a way to improve framing nailer safety.

Source: TOOLS OF THE TRADE Magazine
Publication date: 2002-07-01

By Rick Schwolsky

A team of four Dartmouth College engineering students called the "Ricochet Rangers" think they've discovered a way to improve framing nailer safety and have won a university award for their ingenuity.

"When nailers are fired at too shallow an angle with respect to the wood, there's a danger of ricocheted nails," says team member Joe Horrell. "We've developed a device that disengages the nailer at this angle so it can't fire." The young inventors have applied for a patent and are now seeking an industry home for their device.

The team looked at four possible solutions: containing deflected nails with some kind of shield; modifying nail-tip design; altering wood surface treatments to improve penetration; and modifying nailer design. They decided to address the nailer and set out to develop a device that effectively reduces deflections without changing how framers work.

The students built a testing jig that allowed them to fire a framing nailer at a wide range of angles, and then studied the relationships between the angles fired and the resulting frequencies of ricochets. They factored in the densities of different types of lumber, variables in air pressure, and a variety of nail sizes. During the process, team members developed a deep analysis of pneumatic nailer performance to select strategies for developing and testing their prototypes. "The testing jig was probably the coolest part of our project," says Ranger Kip Benson. "We shot thousands of nails."

The Rangers settled on two prototype designs. "Our first prototype was a round, angled flange installed on the end of the plunger, but it was too smooth and allowed the tool to slip off the work," Benson says. But the next prototype, a recessed, fixed contact, paid off. "This one fits around the plunger and attaches to the magazine," explains Benson. "It disengages the nailer at unsafe angles and has aggressive teeth that keep it from slipping." Field tests with two local framing crews were favorable; framers tried to get the modified nailers to ricochet nails, but couldn't.

"Our final prototype is a very simple design," Benson says, "but it's extremely effective." The fixed-contact device doesn't interfere with nailer operation until the angle between the nailer and the piece of wood decreases below 35 degrees. At that point, the new device contacts the wood and disengages the plunger -- keeping the tool from firing. (As a reference point, 90 degrees is a straight shot into the wood, 45 degrees is a safe toe-nail angle, and many carpenters toe-nail as low as 30 degrees, according to Benson. This testing suggests 35 degrees as the shallowest safe angle for toe-nailing.)

One aspect of the group's research was frustrating, though. Eager to get input from nailer manufacturers and share what they were learning, the group sought contact with members of the pneumatic tool industry. "Many aspects of our project proved hard to do without industry assistance," Horrell says. "But tool companies gave us the cold shoulder. Companies are pretty wary of people working on research and development from outside the industry."

But these guys haven't given up yet. "We'd love to sell the idea," says Horrell, "but our biggest concern is to get someone in the industry to assess its potential to increase safety."

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