Following a thread to a new connection
Dale E. Van Cor with samples of his wave thread products.
Wave thread samples by Dale Van Cor
WINCHESTER, N.H. — Just about 140 years ago, machinist John J. Grant came to Greenfield, Mass., and opened a machine shop on Hope Street to manufacture his invention, a thread-cutting die. That was the beginning of a revolution in the way threaded parts were made. Later, the conglomerate Greenfield Tap and Die Co. continued that change and produced cutting tools that helped the U.S. and its allies win World War II and then rise to become the predominant economy in the world.
Now, a Winchester, N.H., man hopes to again revolutionize the way mechanical connections are made.
“I’ve been working on the ‘wave thread’ full-time for five years,” said Dale Van Cor.
At first glance, the tapered wave threads — which resemble a sine wave in profile — don’t look like they’ll hold firmly.
However, their grip is surprisingly strong, as this reporter found out.
A two-thread pipe connection Van Cor brought to The Recorder’s newsroom seated firmly with a quarter-turn and it took quite a bit of effort to separate the pieces again.
They also stop turning when they’re fully seated.
“You can’t over-tighten them,” Van Cor said. “Once they’re tight, the next threshold is breaking.”
Always seating in the same position makes them suitable for electrical connections, said Van Cor. Several metal connections can be implanted in the male and female threads and will line up every time the physical connection is tightened.
The wave thread makes contact on 100 percent of its surface area, said Van Cor, unlike traditional threads, which inevitably leave a gap.
Total contact has several advantages, said Van Cor. There’s no room for water to get in and cause rust, wave threads create their own airtight seals without relying on gaskets and stress is evenly distributed on each thread, from tip to shank.
“Standard connections put all of the stress on the first couple threads,” he said, “That’s why they break there.”
In a series of destructive tests of wave thread nuts and bolts, said the inventor, the weak point was nowhere near the thread.
“It pulled the heads right off the bolts ... the next step is putting a wave thread on either end.”
Where will a double-ended wave thread bolt break? It could be on the thread or on the shaft. Van Cor isn’t sure, and he’s not risking a hypothesis.
A software designer by trade, Van Cor is not a mechanical engineer, or, at least, he doesn’t have the pedigree of one. He said lack of credentials has caused some would-be-investors to question his credibility, to the point where they won’t even sit down with him.
The idea for the wave thread came to Van Cor while he was working on another project, the Van Cor transmission — a set of conical gears designed to transfer power more efficiently.
“I couldn’t sell the Van Cor transmission to save my life,” he admits.
Though the transmission, which he said was also prohibitively expensive, failed, he found inspiration in the shapes of its conical gears and their teeth.
“I looked at them and said, ‘you know, these look like threads.’”
Now, he’s got that idea out of his head and into real, tangible prototypes. The next step for his threads is market penetration.
If he can get it out there, Van Cor believes his thread will find a snug fit in industry.
“I predict that, within 20 years, 10 percent of fastened connections will be based on the wave thread,” he said with confidence. “Even if I never make money off it, I know it will come into use, because it solves problems.”
To get his thread designs out there, he’s taking an interesting approach.
“I want to build a library of files for rapid prototyping of the wave thread,” he said.
Using the crowd-funding site Rockethub, he’s offering a library of ready-to-print rapid prototyping files for use in 3-D printers, including 57 different wave threads and their UNC counterparts, to anyone who pledges $200 or more.
That will enable others to 3-D print his parts one at a time, but mass production is still an issue.
That’s because there’s no easy way to machine the wave thread, said Van Cor. A tap and die set can’t be made for them, and it’s prohibitively expensive to configure computer-controlled machinery to make them.
A milling machine, for example, would have to move its cutting head in a complex three-dimensional motion while the piece being produced spun in its holder.
Van Cor recalls that he had the wave thread’s design clear in his mind, and drew it in modelling software he created himself. However, he couldn’t figure out how to have it machined.
Then, he discovered rapid prototyping. Rather than machining his designs, he could simply have them printed out.
Rapid prototyping uses three-dimensional printers. Van Cor’s prototype wave thread connectors are made of powdered plaster that is printed in thin layers and held together by adhesives. Another, more expensive method of rapid prototyping can print parts in powdered metal, which is melted by lasers and takes on the properties of cast metal.
Because the process builds the parts in layers, it can make shapes traditional machining processes can’t.
Lathes and milling machines all remove material from the work-piece. Printing parts, however, allows for odd shapes, enclosed cavities, and other things that are hard if not impossible to make in a traditional machine shop.
Though he sees the potential for mass-producing his threads by making them from molded plastic, those molds will need to be machined, making them expensive as well.
For the more mechanically inclined reader, Van Cor gives all the technical specifications of his designs, as well as stress charts and other information, at www.wavethread.com.
David Rainville can be reached at:
or 413-772-0261, ext. 279