Category Archives: Construction Fasteners

How the Phillips Screwdriver Took Over America

The Robertson screw is better in multiple ways, but Henry Ford sealed its fate in the U.S.

By Chris Perkins, August 2020 for Road and Track. Read original article >

The history of the screw, and by inevitable implication, the screwdriver, is complicated. In One Good Turn: A Natural History of the Screwdriver and the Screw, Witold Rybczynski, professor of urbanism at the University of Pennsylvania, traces the metal fasteners to the 15th century, though it wasn’t until the early 18th century that the screw became common. Around then, gunsmiths developed purpose-built tournevis (French for “screwdriver”) for use in the intricate workings of early firearms. A century later, when screws could be mass-produced, factories cranked out accompanying screwdrivers.

According to the American Society of Mechanical Engineers, toolmaker Joseph Whitworth devised Britain’s first standardized screw in 1841. American engineer William Sellers did the same for his country in 1864. Standardized screw heads and screwdrivers emerged later. Early screws used either a slotted head or some sort of square or octagonal drive. As screw production increased, slotted drives became standard. But if you’ve ever cammed (slipped) a screw-head slot, you know why it’s not the only design. Enter Peter Lymburner Robertson. The official history from the Robertson Screw Company says that Robertson, a Canadian inventor and industrialist, cut himself when the blade slipped during a demonstration of a new spring-loaded screwdriver, forcing an epiphany that the world needed a new type of screw. Robertson designed a fastener that featured a square socket tapering towards a truncated pyramidal bottom, winning a Canadian patent for his work in 1907. It’s a brilliant design—Robertson screws won’t easily cam out, and the socket shape helps center the screwdriver, making one-handed operation easy.

The Robertson was perfect for the burgeoning auto industry. Ford began using it to assemble Model Ts at its Windsor, Ontario, plant, where the screw’s time-saving qualities reduced costs by a significant $2.60 per car. But unless you’re Canadian, there’s a good chance you’ve never heard of Robertson screws. That’s because Henry Ford wanted to use Robertsons in all of his plants, and he wanted more control over how they were made. Robertson, by most accounts a stubborn man, wouldn’t agree. No deal was struck, and the Canadian lost an important part of his business. Meanwhile, other engineers worked on their own types of screw heads.

According to Rybczynski, the one that stuck came from inventor John P. Thompson and businessman Henry F. Phillips. A Phillips screw offers many of the benefits of a Robertson and can be driven by a traditional slotted screwdriver in a pinch. Phillips licensed his design to the giant American Screw Company, which got General Motors to use the screw in the 1936 Cadillac. Within the decade, almost all automakers were using Phillips screws.

A Phillips is, arguably, not a better screw than a Robertson. Consumer Reports once wrote that “compared with slotted and Phillips-head screwdrivers, the Robertson worked faster, with less cam-out.” However, cam-out was good for automakers increasingly relying on automation, as it meant screws wouldn’t be overtightened. Today the Phillips is the standard, except in Canada, where the Robertson remains popular, and in Japan, which has its own cruciform screw, the Japanese Industrial Standard.

Next time you strip out a Phillips, shake your fist at Henry Ford.

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Six Fascinating Facts about Fasteners

By Engaged Expert Ryan Castells. Original Article >

It’s always a surprise when you learn something new or interesting about a subject you thought you knew everything about. Well fasteners are pretty cut and dry, right? Read on for a few facts about fasteners that may amaze you!

Fastener Fact 1
If you’ve ever designed a part with a tapped hole, you may have wondered, “How many threads do I need to make a strong connection?” The answer is that it varies, but six at most. Because bolts stretch slightly when load is applied, the loading on each thread is different. When you apply a tensile load on a threaded fastener, the first thread at the point of connection sees the highest percentage of the load. The load on each thread decreases from there, as seen in the table below. Additional threads beyond the sixth will not further distribute the load and will not make the connection any stronger.

Fastener Fact 2
There is a common misconception that black-oxide alloy steel socket head cap screws (SHCS) are ‘grade 8’. This is believed because grade 8 fasteners are so widely available that the label has become associated with all high-strength fasteners. Technically speaking, to be considered ‘grade 8’, a fastener has to meet industry standards for various characteristics. Three of the most important physical properties of SHCS are inconsistent with the ‘grade 8’ classification: tensile strength, hardness, and markings on the bolt head. SHCS are actually stronger than ‘grade 8’, and have more in common with grade 9 fasteners.

Fastener Fact 3
When a bolted connection will be subjected to a fatigue loading, you want to tighten the bolt up to its yielding point for maximum strength. A bolt will experience zero change in load if the applied tensile force is less than the compressive force of the connection. So, a tightly fastened connection is better suited to withstand fatigue loading than a loose connection because the bolt itself will not sense the fatigue load, only the constant force applied due to the clamping of the joint. To ensure that the connection is properly fastened, you can look up the recommended torque for a given fastener type in a table like the one found here. If the applied torque is critical for your application, make sure that you apply the recommended torque to the head of the bolt, rather than the nut. Torquing the nut can result in different nut factors and change the torque required to achieve proper pre-load.

Fastener Fact 4
Have you ever seen a fastener labeled with a 2A or 3B rating and wondered what that meant? That number-letter combo is used to indicate the thread class of the fastener. Thread classes include 1, 2, 3 (loose to tight), A (external), and B (internal). These ratings are clearance fits which indicates that they assemble without interference. Classes 1A and 1B are rarely used, but are a good choice when quick assembly and disassembly are a priority. Classes 2A and 2B are the most common thread classes because they offer a good balance between price and quality. 3A and 3B are best used in applications requiring close tolerances and a strong connection. Socket cap and socket set screws are usually class 3A.

Fastener Fact 5
All fasteners are available with either coarse or fine threads, and each option has its own distinct advantages. Finely threaded bolts have larger stress areas than coarse bolts of the same diameter, so if you are limited on the bolt size due to dimensional constraints, choose a fine thread for greater strength. Fine threads are also a better choice when threading a thin walled member. When you don’t have much depth to work with, you want to utilize their greater number of threads per inch. Fine threads also permit greater adjustment accuracy by requiring more rotations to move linearly.

On the other hand, coarsely threaded bolts are less likely to be cross threaded during assembly. They also allow for quicker assembly and disassembly, so choose these when you will be reassembling a part often. If the threads will be exposed to harsh conditions or chemicals, a coarsely threaded fastener should be considered for its thicker plating or coating.

Fastener Fact 6
When designing a clearance hole for a bolt, it helps to refer to a chart to pick the correct hole size. A useful reference can be found here. Similarly, when pre-drilling a hole that is to be tapped, it helps to have a chart to refer to the appropriate size pilot hole. Such a chart can be found here.

The Incredible Story of the US Army’s Earth-Shaking, Off-Road Land Trains

By Peter Holderith, May 25, 2020.
Original Article for TheDrive.com >

Oh, your pickup has a lift? That’s cute.

You need to get 500 tons of supplies from Fairbanks, Alaska to the Arctic Ocean—a journey of about 400 miles through pure wilderness. There are no roads, very few airstrips, and endless ice. You’re going to have to withstand minus 68 degree temperatures. Also, nuclear armageddon is on the menu if you’re not quick about it.

You, my friend, need a LeTourneau land train.

The DEW Line

By 1954, with the Cold War well underway, the U.S. government realized the quickest way to get a nuclear bomber from Russia to America was to go right over the Arctic Circle. If we wanted any chance of preventing a nuclear apocalypse, we needed to know if Soviet bombers were crossing the North Pole as soon as possible. The Army planned to build 63 manned radar stations in the high Arctic around the 69th parallel (200 miles north of the Arctic circle) as a result. And to transport all the necessary material that far north, it would have to get creative.

Working together, Canadian and American governments determined they would need about 500 tons of materials to construct all of these outposts. With no suitable runways or ports and heavy lift helicopters still in their infancy, it would all have to be hauled in over land. The task of figuring out how exactly to get that done fell to the same company that had been chosen to build the stations themselves—The Western Electric Company, a subsidiary of AT&T.

Solving unsolvable logistics issues wasn’t exactly its forte. But with the help of TRADCOM (U.S. Army Transportation Research and Development Command), it found the one company—more accurately, the one man—that might be able to help.

That’s R. G. LeTourneau To You

Born in 1888, Robert Gilmore LeTourneau was an inventor of heavy machinery. In WWII, 70 percent of the Allies’ earthmoving equipment was created by LeTourneau Technologies, Inc. Having very little formal education, LeTourneau began his working career as an ironmonger. By the time he died in 1969 he was tremendously wealthy and personally held nearly 300 patents. He is buried on the campus of the University he founded in his name, where his gravestone reads “MOVER OF MEN AND MOUNTAINS.” Just a little character development for you.

LeTourneau had spent the early 1950s perfecting a sort of diesel-electric drivetrain for multi-wheeled heavy-machinery. The system—somewhat similar in concept to the sort used on many locomotives—used a combustion engine to spin an electric generator. This generator would send its power to hub motors mounted to each wheel of the vehicle, allowing for multi-wheel-drive without differentials, driveshafts, or the drivetrain losses associated with them.

This powertrain setup will sound familiar to anyone who read our story on the doomed Antarctic Snow Cruiser earlier this month. But LeTourneau’s design was clearly a generation ahead of Thomas Poulter’s hub motors, which weren’t geared properly to handle anything beyond a gentle incline.

The VC-12 Tournatrain

LeTourneau originally applied this technology to scrapers and graders, but realizing the scalability of such a system, he soon moved beyond just earthmoving. In 1953, he dreamed up the first trackless land train to assist logging operations, the VC-12—a four-wheeled control cab with a 500-horsepower Cummins diesel connected to a generator, pulling three cargo trailers on giant, rugged tires, all of which were powered by hub motors to make it a true 16-wheel-drive vehicle. It was brutally ugly, but critically, it worked.

Developed to haul lumber out of forests over rough terrain, the VC-12 had a hauling capacity of 140 tons. A second version saw LeTourneau add three more cargo trailers and another control cab out back with a second Cummins diesel, much like a real train would be set up with multiple locomotives. TRADCOM caught wind of the project and asked for a demonstration.

 

TRADCOM came away impressed. This would be the vehicle to help engineers build up the DEW Line, or at least a version of it. The government decided to pay for the construction of a prototype control cabin built by LeTourneau and designed specifically for Arctic conditions. The result? The TC-264 Sno-Buggy—and, incidentally, monster trucks.
Entering the Arctic With a Giant Machine

The Sno-Buggy had a single, 28-liter Allison V-1710 V12, the same engine used in many American fighter aircraft during WWII including Lockheed’s P-38 Lightning. In this application, it ran on butane and powered a generator, which in turn sent the juice to four hub motors, each spinning two massive 10-foot-diameter wheels. There was no suspension system; any cushioning was provided by the low-pressure tires instead.

Speaking of those huge wheels, four of them eventually made their way to the iconic Bigfoot monster truck (Bigfoot IV and V, to be exact) in the 1980s after owner Bob Chandler bought them from a Seattle-area junkyard for $1,000.

The Sno-buggy had an exceptionally large contact area on the ground, which allowed it to spread its weight over the soft snow and ice. As a result it excelled when tested in Greenland in 1954, and both the U.S. Army and Alaska Freightlines (the Seattle-based company Western Electric contracted to transport their freight north) were impressed enough to order a pair of overland trains. Alaska Freightlines’ rig was the first to be completed, dubbed the VC-22 Sno-Freighter.

Two Trains to Send North

The VC-22 was quickly assembled in a little more than a month. This is impressive considering it was one of the longest (if not the longest) off-road vehicle ever built at the time, with its six cars (including the locomotive) measuring a total of 274 feet. Each car had four driven wheels, resulting in 24-wheel-drive courtesy of two 400 horsepower Cummins diesel engines and the now-familiar hub motor setup. It had a payload capacity of 150 tons.

Thanks to its 7.3-foot-tall wheels and tires, it could traverse nearly any terrain. It had a very successful first season hauling freight to the DEW Line, but a year later it jackknifed and a fire started in the engine room that rendered it inoperable. Soon after, Alaska Freightlines’ contract with Western Electric ended and the VC-22 was hauled out of Canada and left on the side of a highway in central Alaska, where it remains to this day.

Seriously, it’s visible in both Google Maps satellite images and the Street View perspective from Steese Highway outside Fox, Alaska. See for yourself.

Sometime after the VC-22 was completed, the Army’s more complex machine was also finished. Donning the same 10-foot wheels as the Sno-Buggy that impressed officials, the so-called LCC-1 had four cars including an articulating locomotive at the front. Its 600-hp diesel engine sent power to all sixteen wheels, and it was capable of hauling 45 tons.

This machine led a much longer and more successful life than the VC-22. Dispatched to Greenland, it hauled cargo all over the region from 1956-1962. But it too was eventually abandoned in an Alaska salvage yard before being rescued and put on display at the Yukon Transportation Museum in Whitehorse, Canada, where it’s also visible from space on Google Maps.

It might not sound like it, but the Army was very impressed with the LCC-1’s capabilities. So in 1958, officials commissioned the construction of its successor, the longest off-road vehicle ever and LeTourneau’s final triumph: the TC-497 Overland Train Mark II.

LeTourneau’s Gas Turbine Land Train

The TC-497 is a truly remarkable feat of engineering. Capable of hauling 150 tons at 20 mph for nearly 400 miles (this range could be extended by carrying extra fuel cars), it was powered by four 1,170-hp gas turbine engines. Only one of these engines was in the locomotive, with the other three were housed in their own separate cars. It retained the hub motor system from previous overland trains as well, meaning all 54 wheels on the vehicle were powered.

But unlike on LeTourneau’s other land trains, the trailers were also steerable, so the turning radius (which was formerly something like a quarter mile) was now much tighter, as seen in the image above.

The locomotive itself was massive at over 30 feet tall, but its size belied the fact that the smaller gas turbine engines allowed LeTourneau to add living quarters as well. The inside of the locomotive could sleep six and had a complete galley and bathroom. The train’s total length? 570 feet—nearly two football fields. And due to the train’s modular construction, the max length was theoretically infinite. As many power cars as were necessary could be added, along with the fuel to keep them running.

The TC-497 was tested by the Army in 1962 at the Yuma Proving Grounds in Arizona. The results were once again impressive—but so were simultaneous advances in heavy-lift helicopters like the Sikorsky CH-54 Tarhe, a fleet of which could accomplish what the TC-497 promised with a fraction of the time and effort. The time of solving a problem like remote logistics with a massive, almost cartoonish machine like an overland train was over.

In the end, the TC-497 was also abandoned. It sat intact in Arizona for almost a decade before its trailers were scrapped; today only the cab survives, still baking in the desert sun and collecting dust. An unfitting end to one of the largest land vehicles ever made.

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Keeping Golden Gate Bridge in good shape as it turns 80

Original Article by Carl Nolte May 27, 2017 for The San Francisco Chronicle

As the Golden Gate Bridge was being built, Joseph Strauss, the chief engineer, was often asked: How long will the bridge last? His answer was always the same.

“Forever,” he said.

The famous span turns 80 on Saturday, not quite forever, but nearly a lifetime. And how long the bridge lasts depends on a small army of painters, ironworkers, electricians and engineers whose job over the years has taken them to the top and the bottom of the towers and everywhere else on the bridge.

Currently, the Golden Gate Bridge employs 32 painters, five painter laborers, 19 ironworkers, and three ironworker foremen, called “pushers” in the trade. A superintendent is in overall charge.

Though the painters are the most visible of the maintenance crew, it’s the ironworkers, who walk the high steel and build the scaffolding for the painters, who capture the public imagination.

“We have a nickname. They call us Sky Cowboys,” said Phillip Chaney, 57, the ironworker superintendent.

Their job is to replace rusting rivets with bolts, to build scaffolding for the painters and to make sure the bridge is sound.

“The paint protects the steel, but it’s the steel that holds up the bridge,” Chaney said.

“We have a corner office with a view,” said Darren McVeigh, 51, a second-generation ironworker who has been with the Golden Gate Bridge for 15 years and in the trade since 1982.

It’s “rough and dirty work,” McVeigh said, but it’s a good job.

Ironworkers report at 6:30 in the morning and are off by 3. It’s a union job, and the pay is good: $41.53 an hour, according to bridge district figures. It takes a four-year apprenticeship to become a journeyman, and Golden Gate work is especially prized in the trade: Bridge workers get 13 paid holidays, plus vacation.

In other jobs, McVeigh said, “When you don’t work, you don’t get paid.”

On the other hand, working on the Golden Gate presents special problems. The bridge crosses a strait on the edge of the Pacific Ocean, and the strait is famous for its wind and fog.

“Sometimes it cuts through you like a knife,” McVeigh said. “It’s brutal, just brutal. At the end of the day, all you can do is stand under a hot shower.”

The moisture from the fog and rain also add an element of danger to the work because it makes the steel slippery.

No one can be an ironworker who has a fear of heights, but the trade requires a finely honed sense of caution.

“You know the saying: ‘One hand for the company and one hand for yourself,’” McVeigh said.

All ironworkers on the bridge are required to wear a harness — 100 percent tie-off they call it — but there’s a trade-off. With layers of clothing on a chilly day, a body harness and a tool belt, ironworkers look like bears up on the steel. It makes it harder to move, to work.

Though 11 workers were killed during construction, there have been only two fatal accidents involving bridge crews in the past 80 years. In 1970, a painter fell to his death, and in 2003 an ironworker in the employ of a contractor died in an accident during a seismic retrofit project.

And there are also injuries, especially working with steel beams and building scaffolding.

“You get hand smashes and eye injuries, back injuries, bad knees,” McVeigh said.

They also face death, especially when someone is threatening suicide. Bridge workers are trained to intervene and will go to the railing to try to stop someone from jumping. “We put on a harness and tie-off so if they go, we are not going to go with them,” McVeigh said.

Like the others, he has talked some would-be jumpers off the edge. “I’ve lost count,” he said. “Maybe a dozen.”

In the next few years, a suicide barrier will be strung under the deck. The work won’t be done by in-house ironworkers, but by ironworkers hired by the contractors for the job.

The ironworkers’ main work at the bridge is keeping it standing. “There’s an old saying,” McVeigh said. “Rust never rests.”

Chaney points to a long color-coded chart in an engineering office near the toll plaza. It’s a conceptual printout of the bridge, showing the results of regular inspections: green for good steel, yellow for caution, red for problems.

Last year, the ironworkers spent a lot of time replacing some of the 600,000 rivets in the Marin tower. Rusted rivets are removed by a device called a “rivet buster” and are replaced with steel bolts.

Most of this year is devoted to building stages — “dance floors,” they are called — under the roadway deck, so old paint and some steel can be replaced. The stages are surrounded by tent-like structures that keep the old paint and debris from falling into the water.

It takes months to build the stages and the tenting, careful work done under the roadway. It’s not as dramatic as high work on the 746-foot-tall towers, but just as important.

There are other jobs, too. “I have guys working on greasing the bearings on the deck,” Chaney said. Like all suspension spans, the Golden Gate Bridge moves with the weight of traffic and with the wind. The steel moves. “You don’t want a stiff structure,” he said.

After the stages are done, the next big job will be to work on the San Francisco tower, where the effects of wind and rain have left the tower looking a bit shabby, as if it needs a new paint job. “It’s structurally sound,” Chaney said, “but not aesthetically.”

Not everybody can work on what may well be the most famous bridge in the world. Like others on the bridge, McVeigh is proud of it.

“When you are driving to work and see it in the windshield,” he said, “you say to yourself: ‘Wow! Look at this thing!’”

A quiet anniversary

It will be a quiet birthday Saturday when the Golden Gate Bridge turns 80.

Instead, the Golden Gate Bridge, Highway and Transportation District is inviting the public to post personal stories about the bridge on the bridge’s Facebook page and to Twitter @goldengatebridge, hashtag #GGB80 and #MyGGBstory.

The idea, the district says, is to “allow visitors from all over the world to join the fun.”

On the bridge’s 50th anniversary, in 1987, as many as 300,000 people walked on the bridge, causing the arch in the main span to flatten. The bridge staged an elaborate fireworks display on its 75th, in 2012. See Original Article >

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Unique Projects That Call for Custom Fasteners

Custom Fasteners are a vital component of any major construction project. But some projects require more customized fastener options than others due to environmental concerns or weight requirements. We’ve worked on a number of unique projects that required custom fasteners, and have rounded up a few of our favorites.

Otherworldly Applications

Chicago Nut & Bolt has worked on a few projects with applications beyond Earth (while still remaining firmly planted on the ground). The Bioshere 2 in Arizona is a massive 3.15-acre self-contained ecosystem. The goal is to replicate a biosphere on another planet to test the possibilities and realities of space colonization. This was a major undertaking, with construction beginning in 1987 and finishing in 1991. Unfortunately, efforts to replicate food growth and production on a planet like Mars were unsuccessful – but this is valuable knowledge when considering what methods will work on a foreign landscape. By performing trial and error here on Earth, we’re setting up eventual colonists with a better understanding of what to look out for and design around.

In addition to helping build the largest closed ecosystem, we’ve also supplied custom fasteners for the Arecibo Observatory in Puerto Rico. At 1,001 feet across, this is the largest single-aperture telescope ever built. The radio telescope is used for radio astronomy, aeronomy, and radar astronomy. The massive focusing dish of the telescope gives Arecibo the largest electromagnetic-wave-gathering capacity on Earth.

Regional Landmarks

While we have supported many lesser-known projects with far reaching applications, we’ve also supplied custom fasteners for more well-known structures. Perhaps the most widely recognized project is the Golden Gate Bridge, which we regularly supply fasteners for during refurbishing and maintenance.

We’ve also provided fasteners for a more local landmark – the “Son of Beast” record-breaking wooden roller coaster in Mason, Ohio. It’s the tallest and fastest wooden roller coaster in the world, topping out at 78 mph and 218 feet tall. It’s also the only looping wooden roller coaster.

We’re always interested in seeing how our custom fasteners are used once they leave the factory floor. With customers in such diverse industries, it’s an exciting challenge coming up with solutions that meet strict specifications. If you need specialized fasteners for a project, let us know your requirements and we can work with you to find the best solution. You can request a quote online or call us at 888-529-8600 to discuss your needs.

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