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Threaded Rivet Plays Pivotal Role for Folding Rack

Bur Zeratsky, Executive Vice President,, National Rivet & Mfg. Co.

Donny McCall fought sharks and won. A guest on season three of the ABC business-themed show Shark Tank, McCall "respectfully disagreed" with the venture capitalist 'sharks' who said that he needed to outsource manufacturing of his Invis-A-Rackä folding cargo rack to China in order to do what's "best for the business" and create better margins. His insistence on Made-in-America quality and supporting American jobs meant that the sharks declined financial support for his business.

Fortunately, Des Moines-based Dee Zee®, Inc. learned of Invis-A-Rack following Shark Tank. With more than 95% of the approximately 2,800 products Dee Zee sells also made in America, the two parties shared mutual values. After arranging for Dee Zee to have exclusive manufacturing rights for a period of time, the racks are now a standard offering and available at

Another American manufacturer played a pivotal role - literally - in bringing Invis-A-Rack to market. National Rivet & Mfg. Co., a fourth generation family-owned business in Waupun, WI, worked with McCall to design and supply the threaded aluminum rivets that enable Invis-A-Rack's extruded aluminum channels to fold in and out of their bed rail casings. In addition to their structural application, threaded rivets greatly contribute to manufacturing simplicity and improving customer service/warranty repair issues.

Following His Vision

McCall, an independent home remodeler and founder of McCall's Construction, Sparta, NC, didn't like the look of a permanent rack, didn't like how it could prevent loading larger items such as appliances or furniture into his truck bed, and didn't like the increased drag and associated reduction in fuel economy. Yet, like many contractors, his work truck was also his personal truck, and he wanted a rack to carry the occasional ladder, lumber, or canoe.  

"I compare the Invis-A-Rack to 4-wheel drive: you don't need it all the time, but when you need it, it's invaluable," he says.

An 18-month quest led to the first Invis-A-Rack prototype. Along the way McCall learned more about aluminum extrusions, powder coatings, plastics, and dies than he thought possible. Fortunately, a year earlier, he had worked on the home of Wade Stickels from Southeast Engineered Sales, National Rivet's area sales representative. When McCall was ready to move into the manufacturing phase, he contacted Stickels.

"By the time Donny called me, he was so far down the design path that all the lengths he needed were special sizes," says Stickels. "Of course with National Rivet, custom-length fasteners aren't a problem. In fact, they're pretty standard because rivet size is a design afterthought 90% of the time. Fortunately, National Rivet is the go-to source for rivets you won't find in a catalog, and they're also willing to work with customers on minimum order quantities."

The Invis-A-Rack has the following pivot points and following fastener size requirements:

  • The main vertical arm attached to the lower horizontal brace (sitting on the bed rail) uses 3/8 x 3.062 in. threaded rivet.
  • The horizontal arm (going across the truck) that attaches to the top of the vertical arm uses a 3/8 x 1.41 in. threaded rivet.
  • The diagonal brace that attaches to the vertical arm and lower horizontal brace uses a ¼ x 2.04 in. threaded rivet.
  • The diagonal brace that attaches to the vertical arm and top horizontal arm uses 1/4 x 1 in. threaded rivet.

There are also two dowel pins to permit portions of the lower brace and upper brace to slide, and National Rivet also supplied these.

The Rationale for Rivets

McCall knew from the start he wanted a modular rack with pivot points.

"With modularity, if the customer damages one portion of the rack, we can replace just that portion instead of trashing the entire thing," he says. "Compare that to a welded rack. Any damage either ruins the whole rack for the customer or costs us a lot to fix as a warranty repair."

He looked at using a conventional rivet and bushing on either side of the rail, but that, too, had manufacturing and repair limitations. Wanting a fastener that "a guy could just press in and turn with a screwdriver," McCall started experimenting with sex bolts. Also known as Chicago bolts and barrel nuts, they feature a threaded male bolt that fits inside a threaded female connector.

Threaded rivets are similar in that the female portion has a shoulder that stops the male rivet head to create a fastener with a definitive length. As a result, they can securely fasten an Invis-A-Rack joint without squeezing it so tightly that it won't pivot or scrape off the powder coating. Further, if one C channel is a little too wide, the threaded rivet pulls it closer to the correct dimensions.

"Wade Stickels introduced me to the term threaded rivets," says McCall. "He said that National Rivet could put a Phillips head on both components. That would enable anyone with two screwdrivers to install or replace the rivets, fulfilling the manufacturing and repair issues I envisioned." Well, almost.

Making the Grade

McCall was familiar with 6061 'aircraft grade' aluminum from his days in the Navy. However, he originally thought of anodizing the rivets, and 6061 doesn't anodize well. As a result, the initial order of threaded rivets used 5056 aluminum.

"Unfortunately, the manual assembly operation at Dee Zee stripped the heads of the rivets fairly often, so they'd have to drill them back out. That wasted time and materials," says McCall, who remains connected to Dee Zee as a consultant.

To solve the problem, McCall ended up working directly with Bart Ludjack, a sales engineer at National Rivet, who recommended using 2117 T4 aluminum. This grade has decent machinability, and National Rivet hardens and ages it in-house to control quality. The 2117 T4 grade has a tensile strength of 43,000 psi and yield strength of 24,000 psi, which met the Invis-A-Rack load demand of supporting 500 lb.

"The 2117 T4 grade solved the problem of stripping during assembly," says McCall. To solve the problem that all threaded connections have, namely backing out under vibration, Loctite® Dri-Loc® threadlocker is applied to the male portion of the threaded rivets before they are shipped to Dee Zee.

American Success

In the time that McCall has been selling Invis-A-Rack, he has only had two returns. The first was because the customer bought the wrong size for his truck. The other customer initially said that he was only carrying a couple of ladders when the rack broke. McCall requested that the customer send in the damaged part.

"After looking at the structural damage, I deduced that he must have had a heavy load of tools in the bed of his truck and, after removing them, the truck rode a little higher. That was enough to knock the back portion of the rack down as he drove out of the garage," says McCall.

The customer not only gladly purchased the replacement components, he ended up being a repeat customer . . . because he hit the top of his garage again.

"I tell that story because it fulfills my vision of creating a modular folding rack that the customer can install and repair himself," says McCall.

Thus far, the Invis-A-Rack system has been a success from every angle. Dee Zee's purchasing volumes enable the company to make suitable margins, while its online sales model provides the necessary volume.

"There are companies that have been doing this far longer, but they're not getting the public visibility that I have right now," McCall says humbly. "I'm glad to carry the banner, because it's exactly what I believe in. I want to do what I can as one person. If that inspires more people, pretty soon we could be making a lot more products here in America."

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