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Fast and Secure PUBLIC ACCESS

How Much Proof is Tamperproof?

[+] Author Notes

Associate Editor.

Mechanical Engineering 127(06), 32-35 (Jun 01, 2005) (4 pages) doi:10.1115/1.2005-JUN-2

This article highlights the beauty of an early tamper-proof design of how it can be installed with almost any straight-bladed screwdriver, as opposed to many tamper-resistant screws that came later, which required special drivers for turning them in either direction. A drawback of the one-way, slotted variety is that it is difficult to remove with any tool save maybe a drill. Hence, Tamperproof sells a tool for removing them that uses two prongs to cut notches in the head. Unlike the one-way, slotted style, other tamper-proof designs are meant to be taken out occasionally. Unfortunately, there is not much control anymore over distribution of the driver bits for designs like the Torx tamper-proof screws, so they go only as far as making vandalism inconvenient. Prisons are big users of tamper-proof fasteners. In such places, even innocuous shower drain covers are honed into knives by convicts who, between working on their pecs at the gyms and their cases in the law libraries, find time to work on their projects in the prison machine shops.

The restroom partitions on the 22nd floor at ASME's head-quarters stay put, thanks to nonremovable sex bolts. One flight down, however, it's the glue of honesty that's keeping a dollar bill changer stuck to the wall. There, only a couple of angle brackets and a few ordinary screws hold the coin machine in place.

You'd expect things to be the other way around. Stealing a change maker, as far as that goes, promises more of a pay out than making off wit the men's room walls. Yet, the facts Speak for themselves.

The bathroom partions are fastened the way that they are because someone, somewhere, must have written a spec that went something like:"Pilasters shall be 82 inches high and fastened into a 3-inch-high pilaster shoe with a stailess-steel,tamper-resistant Torx head sex bolt."

A sex bolt, by the way, is what partition makers call those two-part fasteners that consist of an externally threaded screw on one side, and an internally threaded, tubular nut on the other. When joined, the two parts form a smooth cylinderical pin with screw head caps on both ends. It's called a binder post-perhaps in deference to the more delicate sensibilities os some librarians. They're also called barrel bolts.

In ASME's case, the bolts are capped by those screw heads—you've seen them—that turn in one direction but give a screwdriver no purchase when it's time to back them out.

That particular screwhead style is known as the oneway, slotted type, according to Lew Friedman, president of Tamperproof Screw Co. in Hicksville, N.Y. The beauty of this early tamperproof design is how it can be installed with almost any straight-bladed screwdriver, as opposed to many tamper-resistant screws that came later, which required special drivers for turning them in either direction. A drawback of the one-way, slotted variety is that it's difficult to remove with any tool save maybe a drill. That's the point, of course—although Tamperproof does sell a tool for removing them that uses two prongs to cut notches in the head.

Tamperproof markets a variety of tamperproof fasteners, from Phillips pinheads to the especially vexing Opsit, so named for its left-handed thread that works contrary to most juvenile delinquents' turn-right-fortight value systems. The one-way, slotted type remains popular for economic reasons; it can be cold-headedformed in a single operation. That makes it inexpensive to produce, Friedman said. For licensed designs like the Phillips pinhead, Tamperproof buys the basic screw and drills each fastener head to receive a pressed pin. It's that secondary operation that makes those varieties costlier to produce.

Unlike the one-way, slotted style, other tamperproof designs are meant to be taken out occasionally. Unfortunately, there's not much control anymore over distribution of the driver bits for designs like the Torx tamperproof screws, Friedman said, so they go only as far as making vandalism inconvenient. In Australia and New Zealand, the Torx design is virtually unmarketable as a tamper-resistant fastener because its drivers are everywhere.

For the Torx Plus tamper-resistant design, maker Textron went with a plan for tight distribution of driver tools, according to Tim McGuire, director of application engineering for Textron Fastening Systems in the Americas. The drivers can be purchased only by original equipment manufacturers and authorized service personnel. The company also replaced the nominal six-point Torx Plus socket with a five-point design, since the Torx Plus sockets were designed to be removable by the original Torx bits when a correct Plus bit was unavailable. Naturally, any six-lobed Torx tamperproof bit would have been able to take out the tamperproof Plus screws if that design had not gone to five lobes, McGuire explained.

Textron's biggest tamper-resistant market is automo-biles, ever since the mid-1990s, when the government mandated that emissions controls be locked down. All sorts of devices and techniques were proposed, among them hex recesses filled with ball bearings, wired fasteners, and even tamper-evident snap ring caps.

The idea was to keep backyard mechanics and even unqualified service stations from accessing setups critical to a car's emissions performance. These were better left at their factory settings, or adjusted only by qualified mechanics armed with the proper tools. In reality, only tamper-evident fasteners were really needed.

Rarely do these designs deter anyone other than amateur crooks from making off with the goods. For true theft proofing, some facilities turn to ac tual keyed screwheads, such as the system developed recently by Bryce Fastener Ine. of Gilbert, Ariz. Bryce's several security screw styles depend on controlled access to the driver bits. In some cases, the company controls bit access. In other instances, the user controls it. The company claims that 16 million different shapes are possible with its Keyed-Iok product.

Robert Bancroft, a senior display systems engineer at the Rochester Institute of Technology's Educational Technology Center, in Rochester, N.Y., was able to slow a small crime wave on the campus several years back with the help of Bryce fasteners. After 10 of nearly 200 clas sroom mounted video projectors had fallen victim to thievery, Bancroft went looking for a solution. It came in the form of replacing the nearly two dozen 10-32 screws that mount each unit with Bryce Keyed-lok fasteners. Since then, the institute has lo st only a single unit, the result of "brute force," Bancroft said, which probably incapacitated the machine anyway.

A new economy: Fasten commodities like bathroom doors with one-way security screws (left). leave money machines to fend for themselves (center). Tamper-resistant screws (right) have long been keeping folks honest.

Grahic Jump LocationA new economy: Fasten commodities like bathroom doors with one-way security screws (left). leave money machines to fend for themselves (center). Tamper-resistant screws (right) have long been keeping folks honest.

Robert Bancroft points out how Keyed-lok fasteners quashed criminal activity at RIT, where bandits were converting projectors into cash.

Grahic Jump LocationRobert Bancroft points out how Keyed-lok fasteners quashed criminal activity at RIT, where bandits were converting projectors into cash.

"There are no patentable drives left," said Bryce's president, Bryce Campbell, explaining that anyone can now buy Asian knockoffs of tamperproof drives at auto-parts and some neighborhood superstores.

Textron's McGuire doesn't agree. The next drive may just not have been invented yet, he mused, recalling how old-timers around at the time the Torx idea was gestating warned of the heap of trouble the young guns were heading for. McGuire, himself a veteran now, sees new fastener ideas come along all the time.

But any tamper-resistant design has a finite life because the patents on its features eventually expire and the drive bits become more widely available. This is beginning to happen with the Torx Plus design, even with Textron's tight control. The design came out in the early 1990s.

The first tamperproof screws may have been developed by Chicagobased Safety Socket LLC, which makes fasteners for Bryce, some 25 years ago for the Western Electric Co. to combat phone booth pilferage. Other early users included Southern Steel in San Antonio, Texas, which builds jailing systems, and World Dryer Corp. of Berkeley, Ill.

Prisons are big users of tamperproof fasteners. In such places, even innocuous shower drain covers are honed into knives by convicts who, between working on their pecs at the gyms and their cases in the law libraries, find time to work on their projects in the prison machine shops.

On and off your command

Textron Fastening Systems' Intevia eliminates the need for tool to touch fastener. Gone, in fact, is the need for any fastener access at all. Intelligent fastening instead works wit embedded electronics that actuate, through smart materials, traditioanal mechanical locking devices such as pins, clips—even threads. Electronics control the energizing of shape-memory alloys, say, or piezoelectronics. These materials can remember two distinct shapes and can switch between them in response to heat, electricity, or magnetism. Authorized users can latch or unlatch the fasteners remotely.

 

Grahic Jump Location 

According to Safety Socket's president, Richard Payne, the company never patented the idea for pushing a pin into a hex socket. The company started making the fasteners by pressing dowel pins into holes drilled into the hexes, until deciding that a more efficient process was needed, Payne recalled.

It was in figuring out how to cold-head the fastener and extrude the pin that some real effort took place. It's done in three stations, using a little heat to soften things and make the metal "back extrude" into the forming tool, Payne explained. The company can make the fasteners in low carbon steel, which can be case hardened only, and from alloy steel, which can be throughhardened for higher tensile strength and torque capacity. In stainless steels, the company has found that the 400 grade heat-treated variety flows better than the 300 grade does.

"It's more pressing than smashing," Campbell added, describing the process of cold-heading the special fasteners.

Bryce fasteners have recently been used in combating airbag theft, which, according to the National Insurance Crime Bureau, amounts to a $50 million-a-year problem. The company's fasteners are used by cable TV providers, retail stores, and museums, he said. One inventor has patented the idea of using one in a rifle breech as a potent alternative to everyday trigger locks.

Another company, McGard Inc. of Orchard Park, N.Y, also fights airbag theft with uniquely keyed nuts that have long held similar spots of responsibility in keeping alloy automobile wheels locked on. The company markets its security products to water and energy utilities as a means of protecting revenue. Its Web site shows one holding down a manhole cover.

Start looking around and see how much of America is vulnerable not only to vandalism—a relatively minor, if costly, nuisance—but to certain groups bent on harm. Joke as we may about sex bolts and bathroom thievery, tamperproof fastening has an increasingly important role to play, Campbell said. It may even be time to sound a mild alarm.

Textron had been approached previously about manufacturing uniquely keyed fasteners.

The company managed to avoid signing up for the task every time, McGuire said. But, one day, Textron's intelligent fastenings systems, dubbed Intevia, may end up doing just that. With electronics fulfilling the requirements for unique codes, an Intevia fastener could easily hold a spare tire in place, to be disarmed only by pressing a button on the key fob.

According to Textron Fastening Systems' Seshu Seshasai, executive vice president of technology, the intelligent fastener the company introduced about two years ago is now seeing its first commercial application as a replacement latch for aircraft closet doors. The fasteners will replace heavier, remotely actuated, solenoid-operated levers with the lighter Intevia, which promises to improve reliability, Seshasai said.

It may be the beginning of a totally new approach to tamper-resistant fastening for high-value items like airbags. Not for bathroom partitions, though—there, the cheap one-way screw may always reign

To make the Textron Torx Plus screws on the left tamper-resistant needs a geometric change and the addition of a pin in the head. Way back, Safety Socket developed a method to cold-head fasteners with a little heat so the metal would "back extrude" into the forming tool to create the central pin.

Grahic Jump LocationTo make the Textron Torx Plus screws on the left tamper-resistant needs a geometric change and the addition of a pin in the head. Way back, Safety Socket developed a method to cold-head fasteners with a little heat so the metal would "back extrude" into the forming tool to create the central pin.

Copyright © 2005 by ASME
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