Spinoff is NASA's annual publication featuring successfully commercialized NASA technology. This commercialization has contributed to the development of products and services in the fields of health and medicine, consumer goods, transportation, public safety, computer technology, and environmental resources.
More than 30 years after a researcher at NASA's Goddard Space Flight Center tested and demonstrated the significantly improved fastening ability of an altered screw-threading, the design has helped Cobra Puma Golf achieve the lowest-ever center of gravity in a golf club.
An enduring problem with threaded screws is that vibration can eventually jar screws and bolts loose. Few fasteners experience more intense vibration than those in a rocket engine. In the early days of the Space Shuttle Program, NASA took an interest in fasteners that could endure the vibrations of repeated liftoffs, as well as extreme temperature variations that cause metals to expand and contract.
That was when NASA came across an invention by Horace Holmes of Holmes Tool Company known as Spiralock threading, a slight alteration to traditional threading that promised considerably stronger joints.
Threading in female nuts and bolt holes had always precisely mirrored that of the male bolts that screwed into them, allowing them to perfectly follow each other's contours. The result, however, was that there was little if any pressure for most of the length of the connection, with about 80 percent of the clamp load being carried by the first two threads. Holmes’ idea was to blunt the trough of the female thread with a 30-degree wedge ramp. The result was that most of the length of a bolt's threading ridge would be forced against the wedge in the nut, causing a more even distribution of the load along the length of the connection, with the first two threads now carrying just 25 percent of the load.
It wasn't until the 1984 publication of a lengthy study by Goddard researcher James Kerley that Spiralock began to be used more widely. Kerley found that Spiralock nuts could withstand double the vibrations that would loosen a standard nut, and for 10 times as long. They didn't lose clamping power after a bolt and nut combination was torqued on and off 50 times, far exceeding NASA's demand for a fastener that could be reused at least 15 times. Shortly thereafter, Spiralock was applied to more than 750 tube clamps, joints, and brackets in a set of space shuttle main engines, where it easily withstood further testing. The design soon was incorporated into missiles, diesel engines, oil wells, seismic vibrators, broadband fiber-optic networks, human joint implants, pacemakers, and many other systems.
In early 2013, employees of the Center for the Advancement of Science in Space (CASIS), which manages the International Space Station's (ISS) U.S. National Laboratory, began a partnership with Cobra Puma Golf. Before long, the company was consulting with employees of various NASA field centers, and by September 2014, CASIS had secured Cobra Puma Golf a slot as a customer for a research payload to the ISS. The company sent up 20 tiny spaceport doors, modeled after the ISS cupola, for a one-month experiment testing the hypothesis that silver would deposit more uniformly and with larger crystalline growth in zero gravity, resulting in higher durability.
The door was to be a unique feature of Cobra Puma Golf's KING LTD Driver, but an unforeseen problem had arisen. The spaceport door turned out to be in an extremely high-vibration, high-load environment. After hitting golf balls over and over, the portal — which screws into the bottom of the club's head — began to come unscrewed, much like a bolt in a rocket engine after repeated use. Cobra Puma Golf researched NASA's use of fasteners in high-vibration environments and came upon Spiralock threading, which was incorporated around the spaceport door to help alleviate the effects of vibration occurring during impact.
To cut the thread into the clubs, the company acquired a licensed cutter and gauge from Spiralock, now part of Stanley Engineered Fastening. The spaceports now hold fast, and the company started selling the drivers in November 2015. The door gives access to the inside of the golf club. Normally a finished driver head is just under its target weight — typically around 200 grams — because it's easier to add weight than to subtract it. Then, just enough hot melt — a sticky substance that doubles as weighting material and debris catcher — is injected through a small hole in the sole of the club. Instead, with the spaceport door in the KING LTD Driver, a tungsten weight can be inserted. The metal can be filed to the precise weight necessary for each club before it's locked in place. The aluminum door itself, which features a polycarbonate window into the club's interior, also serves as a 16-gram weight.
All this has helped Cobra Golf make what it believes is the first zero-center-of-gravity golf club, meaning the center of gravity for the entire club is on the neutral axis, an imaginary line extending back from the center of the club's face, maximizing the transfer of energy from club to ball. The door to the club's interior also allows the company to make custom clubs, adjusting the size and position of the tungsten weight to suit individual golfers’ styles.