Rhuddlan, North Wales.
The bag is full. Full of metal of varying shapes, sizes, weight and condition. There’s a dozen of them in there, most of them with the COBRA brand etched into the head. But there’s an odd one out.
That particular 37-inch piece of 316L stainless steel is being shared between a handicap golfer and the local club professional as balls are clipped towards the green. It is not the customary way to play a round of golf, but there’s a new toy to play with courtesy of TCT Magazine.
Passing the new COBRA Golf LIMIT3D 7-iron – a club ‘designed for better players’ – back and forth, the pair are aiming to strike towards the green 150 yards away. But they’re falling short and pulling left. To get themselves out of this spot of bother, they’re returning to their own trusty wedges, whose weight, behaviour and feel they are much more accustomed.
Los Angeles, California.
In LA, a familiar sight. The LIMIT3D 7-iron is passed back down a lengthy queue after every swing. We’re at RAPID + TCT 2024, where nTop has allocated a sizeable amount of floor space to a golf simulator, allowing attendees to have a strike with the latest piece of sports equipment to be enabled by additive manufacturing.
For nTop, the LIMIT3D golf club head is considered among the best examples of what the nTop software can facilitate, with CEO Brad Rothenberg telling TCT: “The engineering logic that’s built into the computational model that they’ve generated is what impressed me the most. I was blown away by it.”
Carlsbad, California.
It was a year ago when COBRA Golf President Dan Ladd tasked Mike Yagley, the company’s VP of Innovation, with using the metal 3D printing technology residing in his department to commercialise a new golf club head ‘very fast.’ Very fast, it is said, meant within 12 months.
Typically, the Innovation department gets the ball rolling on a new product creation, before handing over whatever ‘crazy stuff’ they have developed – be it materials, aerodynamics, weighting systems, or a 3D printed golf club head – over to Design and Product Creation. But because of the short turnaround, the LIMIT3D golf club head stayed in Innovation.
Innovation is where the spark was lit for the KING Supersport-35 putter, which would be manufactured with HP Metal Jet technology via Parmatech in 2020. It was a good base to start from, helping the team to ‘learn the hard way’ that additive manufacturing is ‘a lot more complicated than anybody thinks.’
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Exhibit at the UK's definitive and most influential 3D printing and additive manufacturing event, TCT 3Sixty.
COBRA, however, has deemed it worth their time and resources. For the LIMIT3D 7-iron, it was decided early on that COBRA would switch to a Direct Metal Laser Sintering process for the production of this club head because it intended to incorporate a complex internal lattice structure.
“If you think about the binder jet process,” COBRA Golf Director of Innovation Ryan Roach explains, “you have to take the printed part and sinter it, and the part isn’t super strong before you sinter it, so if you have an enclosed volume and want to get the powder out, it’s very difficult. With the DMLS process, that part is strong, layer by layer, melted into place, and we can be a little more rough with it afterwards. And we can make more intricate structures because we don’t have to worry about being careful getting the powder out.”
COBRA Golf
The LIMIT3D club head was printed in DMLS
The internal lattice structure – more complex than the one visible on the blade's surface – was a key focus during product iteration. COBRA had started with a body-centred cubic lattice cell, which was ‘saving so much weight’, and gradually moved towards a dodecahedron cell that weighed more but provided the stiffness COBRA was looking for.
“People skilled in the art,” Yagley borrows a phrase from the IP world, “would say, ‘wow, look at what COBRA did to make this happen!’. Subtle, but nerds would really nerd out on it. Our marketing people talk about magic tricks, there’s a magic trick in there.”
Los Angeles, California.
Given its nascency, there are few people more skilled in the art than the founder and CEO of the company enabling this computational lattice optimisation. nTop, Roach and Yagley agreed, ‘jumpstarted’ the LIMIT3D project, allowing COBRA’s Innovation team to ‘very easily, very quickly’ switch and analyse lattice structures.
At RAPID + TCT, Rothenberg is effusive with praise for the way COBRA has implemented the nTop software.
“It’s just so impressive,” Rothenberg tells TCT. “They were building this incredibly complex computational model of the club head so that they can change the parameters, ‘let’s move the centre of gravity, let’s see what happens if the moment of inertia is further out, let’s optimise the location of weights in this club head, let’s optimise the wall thickness of it.’ It goes way beyond taking a dumb solid and filling it with a lattice. They built in the requirements for the club into a computational model and they could change those constraints and generate a new club.”
Carlsbad, California
The lattice that COBRA landed on is printed with the rest of the body, touching the base and back of the club head to maintain the required stiffness, while also delivering on the desired impact feel.
How the club feels is of paramount importance to any golfer, from those improving their swing at the driving range, to those competing in the Majors. As such, it needed to be considered right alongside the high loads a 7-iron will experience through the swing and connection with the ball.
It’s a question of shape and weight. Any golfer is going to have their preferences, many deciding within seconds whether a particular club is for them, and many taking several rounds of a course to get used to their new clubs if they persevere. From the manufacturer’s side, there are specific weight ranges that need to be conformed to, so what COBRA embarked on with the LIMIT3D 7-iron was a mission of weight redistribution.
With nTop’s computational design capabilities, COBRA was able to additively manufacture a club that boasted a 33% weight optimisation, with discretionary weight being repositioned to optimise the feel, centre of gravity and moment of inertia. These discretionary weight savings allowed for up to 100g of tungsten to be positioned low in the heel and toe to enable a compact blade shape and deliver on those performance gains.
“The advantage of taking the weight out is we can then put it back and concentrate it in places where you can’t normally because you need all that weight to make the form,” Roach says. “When we talk about [taking out] 100 grams of weight in the head, the head weighs between 240 and 300 grams, so you’re talking about roughly a third of the weight that you’re now repositioning. That’s why you’re seeing this performance difference.”
COBRA Golf
“It’s more about weight movement than weight reduction,” Yagley summarises, before explaining: “If you put more mass on the perimeter, you are increasing its resistance to twisting [or its moment of inertia]. If you hit the middle, you hit a 175-yard shot. Hit it on a toe, normally for a 7-iron, you lose 20 yards. With the LIMIT3D, they only lose five or ten. Decent golfers should notice pretty quickly, it flies like a 7-iron, it feels like a 7-iron, but when I ‘miss’, it does not go as short as I think, because of that moment of inertia increase that’s invisible to the player.”
Rhuddlan, North Wales.
Over the course of a few weeks, the handicap golfer and club professional continue to trial the LIMIT3D golf club. They take it to the driving range, use it on a simulator, and hand it off to a variety of scratch players too. There is variance in the experience, but they all come back to the same point of contention.
“With the single club, it didn’t work. But with a full set and more time to get used to the weight, you’d probably see the improvement.”
Carlsbad, California.
So, it’s back over to COBRA Golf. After launching the LIMIT3D 7-iron, is there a will to keep going with this technology? And to scale should the demand be there?
“Definitely. What we are dreaming of right now is so exciting. And we are just scratching the surface,” notes Yagley.
“This process scales nicely,” added Roach. “We’re very close to being able to do that. When we have something that we feel is a superior product that people are going to want, we look into that.”
“If there is a demand for this, we can scale it up,” finished Yagley. “We will work with vendors to scale this up. Will it replace casting and forging? I doubt it. You can make a lot of those fast and it is still a lot less expensive. But 3D printing has its purpose and you can do things with 3D printing that you cannot with forging and casting. So, if the demand is there, we’ll be able to do it.”
This article originally appeared inside TCT Europe Edition Vol. 32 Issue 4 and TCT North American Edition Vol. 10 Issue 4. Subscribe here to receive your FREE print copy of TCT Magazine, delivered to your door six times a year.
