Front Street Shipyard’s new water jet cutting machine (Photo: Front Street Shipyard)
Front Street Shipyard’s new water jet cutting machine (Photo: Front Street Shipyard)
Front Street Shipyard recently acquired the largest water jet cutting machine in the state — a five-axis, 3D, Suprema DX 1340 model from Waterjet USA. It cost close to $1 million and can cut just about anything.

Much of the actual cutting is done by garnet sand, which is mixed with the water and shot out of a nozzle in a high-pressure stream — three times the speed of sound, according to the Waterjet website, or faster than a bullet by half.

The machine includes a large rectangular tank filled with water to catch debris. Just below the surface lies a metal grid to support the material as it is cut. The nozzle of the water jet is mounted on a gantry that allows it to travel, guided by computer, to any part of the bed. A lathe attachment makes it possible to cut pipes.

All of this has been a long time coming — in 2018, the shipyard was awarded a $667,000 grant from the U.S. Department of Transportation Maritime Administration’s Small Shipyard Grant Program toward the purchase, which totaled about $900,000, shipyard president JB Turner said this week.

At the time, the water jet was going to be used to cut large composite panels for high-speed ferry boats by Arcadia Alliance, a partnership between the shipyard and Norwegian carbon-fiber ferry builder Brødrene Aa. Arcadia Alliance is still seeking contracts, Turner said, which could include ferries running between Belfast and Islesboro, or boats to service offshore wind turbines. But for now, the water jet is being used for shipyard refit projects and, as the centerpiece of the shipyard’s new manufacturing arm, outside contracts. Since January, they’ve cut about 900 pieces for Kenway Composites in Augusta and have done jobs as small as cutting a glass tabletop and a set of rubber gaskets for a customer who was restoring an antique fire pump.

Something different

Since 2018 when plans for the water jet were announced, I’ve been curious about the limits of a million-dollar cutting machine. Would it be the opposite of a 3D printer, capable of reducing a hunk of solid material into any form that could be rendered on a computer? If you put a block of marble on the flatbed, could you download a computer-aided-design template of Michelangelo’s Pietà and burn off a few copies by lunch?

A page dedicated to the water jet on the shipyard’s website includes the tantalizing claim “any material, any thickness.” The paragraph that follows hedges a maximum thickness of 300mm, which is just shy of a foot. Craig Picard, the shipyard’s in-house designer, would later describe the “Z travel,” or the height from the nozzle to the deck, topping out at 20 inches. So, no Pietà. But with five-axis control and mechanical tolerance of four thousandths of an inch, what smaller wonders could it perform?

When I visited last week, I brought three items for consideration. After locating a downloadable AutoCAD template image of “The Last Supper,” I brought a small canvas in hopes that it could be engraved. The canvas was actually a grain of rice. It seemed like a long shot, but this was a million-dollar cutting machine.

I also brought an acorn squash and, in the event that the test material absolutely had to be flat, a vinyl LP of the Doobie Brothers’ “Minute by Minute.”

Picard and Joel Wescott, the technician operating the machine that day, hadn’t cut these particular materials before, but they had some insights about how it might go. The grain of rice was quickly determined to be too small — the water jet can follow a pattern to within fractions of a millimeter, but the beam of water itself is about the diameter of a pencil lead and it goes directly through the material rather than etching away at the surface. The head of the water jet can tilt, but it essentially functions like a bandsaw, in which the blade is made of water and sand.

The vinyl record could be cut, Picard said, but being potentially porous, it would take some caution. If the water jet hits a pocket of air, he said, it tends to go sideways and leave an exit wound of sorts. To cut laminates and other porous materials, the head of the water jet is equipped with a regular drill on the side, which punches a pilot hole before the water cutting starts. The water jet then starts its programmed movement from the hole and moves sideways into the material.

Wescott settled on the squash. It took him about 20 minutes to prepare the water jet, a process that included cutting a jig out of plywood to hold the gourd in place, taking measurements to let the nozzle know where to find the target and programming the computer. Picard wondered aloud if the squash would explode or if it was soft enough that the jet would pass right through. I wondered what Wescott was going to do to the squash. When he let it rip, the nozzle glided down to just above the squash and blasted it. Water churned up through the fluted gaps between gourd and jig, but nothing exploded. After about 30 seconds, the cap of the squash dropped out of sight and the machine shut off. Wescott lifted the squash to his face and looked through a perfectly cylindrical hole cored out of the center. The top edges were so clean they were sharp.

Picard said the sand costs about 50 cents a pound, and the machine uses about a pound per hour of operation. The question of when to use the water jet is simple: If it’s faster than having someone do it by hand, he said, use the water jet.