Miller Equipment Key in Constructing Dobbertin's Aluminum Hydrocar

Miller Equipment Key in Constructing Dobbertin's Aluminum Hydrocar

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One of the more interesting challenges is welding the 5086 marine-grade aluminum skin to the 6061 angle aluminum framework. Using a combination of tungsten inert gas (TIG) and metal inert gas (MIG) processes in building the HydroCar, Dobbertin has found that a Miller Syncrowave® 250 DX and an all-in-one Millermatic® 251 MIG welder matched with a Spoolmatic® 30A spool gun provide him with the versatility he needs to efficiently weld these two integral pieces of the car's frame.

"Dad, I want to go water skiing - can I borrow the car keys?"

Sounds absurd, doesn't it? Rick Dobbertin of Syracuse, NY sees this as a popular question for future generations of teenagers looking to go for a joyride. Dobbertin's HydroCar, an amphibious vehicle capable of reaching 50 miles per hour (mph) on water and 125 mph on land, may just be the prototype that could make that question more common in coastal regions and on freshwater lakes everywhere.

With every dream comes challenges - Dobbertin's HydroCar is still in its production stages in a large pole barn attached to his home, set to officially take to the water in Spring 2005. One of the more interesting challenges he's faced is welding the 5086 marine-grade aluminum skin to the 6061 angle aluminum framework. Using a combination of tungsten inert gas (TIG) and metal inert gas (MIG) processes in building the HydroCar, Dobbertin has found that a Miller Syncrowave® 250 DX and an all-in-one Millermatic® 251 MIG welder matched with a Spoolmatic® 30A spool gun provide him with the versatility he needs to efficiently weld these two integral pieces of the car's frame.



Dobbertin's Hydrocar, still in its production stages, should be completed in Spring 2005.


"The Miller machines made it possible to do this, especially the Millermatic 251," says Dobbertin. "I can get in vertical, horizontal, upside-down, anything I want, any angle I want. I can stick the gun right up, even if it's a spot I can't see very well, pull the trigger and there's my weld, right where I want it, perfect every time." 

Rick Dobbertin Gets his Sea Legs

Having already won two of Hot Rod Magazine's Car of the Year awards, once in 1982 for a soupped-up 1965 Chevy Nova and in 1986 for a 1985 Pontiac J2000, Dobbertin turned his eyes to the sea in 1990. Fielding many requests to showcase his cars in places like Australia and Sweden, he was intrigued by the idea of building a car that could "drive" to these distant locales. From this intrigue came the Orbiter(a milk tank truck turned into water cruiser(that he drove from upstate New York to Florida, and launched it from there to places like the Dominican Republic, St. Maarten, Colombia, Venezuela and Panama. After making landfall in Panama, he drove it home through Central America and back into the U.S., covering 28 countries and 38 states. The Orbiter was, however, not really a practical vehicle that could be bought and used by the average citizen. He sees the HydroCar as a machine that could someday have a regular place in island communities and coastal regions.


"The HydroCar is more of a sportscraft, a recreational vehicle," says Dobbertin. "It will be a two-passenger vehicle with the capabilities of a pick-up truck. It would be ideal for somebody with a construction company that did renovation work on an island. There are many island homes where, if you want to get a gallon of milk, you have to go to your dock, get in your boat, cruise to shore, park the boat, tie it off, get in your car and then reverse the process to come home. The HydroCar would make the process much easier."  Welcome to the lifestyles of the rich and famous.

While Dobbertin recognizes it as a niche market, he sees the HydroCar as a viable option for homeowners and has already seen some interest from emergency response professionals who work in areas bordered by larger bodies of water. On a basic level, the HydroCar is a four-wheel drive vehicle (with a twist. For regular land operations, the HydroCar operates in front-wheel drive. When entering the water, the driver shifts into four-wheel drive, which includes the large propeller on the back of the car. Once in the water, the sponsons (think pontoons) that served as fenders on land lower 8 in. and provide flotation; the wheels retract 5 in. and are covered up by aluminum flaps that make the bottom of the car as slippery as a race boat. The driver than shifts into rear-wheel drive, which stops the wheel rotation and powers the boat solely with the propeller, reaching speeds of 50 mph. 


In constructing his HydroCar, Dobbertin carefully picked his resources and designed a car that would comply with international road laws while withstanding the rigors of sea travel, including exposure to salt water. To do that, he incorporated an 1/8-in. wall 5086 marine-grade aluminum skin to the outside of the car to withstand corrosion. Welding aluminum is tough to begin with, but when taking into account that many of the welds connecting the skin to the 6061 aluminum frame were upside down or in awkward positions, Dobbertin needed a spool gun. 


"I've wanted a spool gun since 1986," claims Dobbertin," but never really had a reason to get one until now."

To weld the skin to the frame, Dobbertin uses the

Spoolmatic 30A spoolgun.

Constructing the HydroCar

Dobbertin started out with two, twenty-foot I-beams and created a giant welding table in his garage. He constructed the car's center frame (which supports the cab, engine and other critical components) out of 2-x 2-in. 304 stainless steel box tubing (.120 wall) with 1-x1-in. braces for its strength. The structural and sponson frameworks are built out of 2-x2-in. and 1-x1-in. 6061 angle aluminum (1/4 in. wall), to which the1/8-in. 5086 aluminum skin is welded.      


The car's 304 stainless mainframe and 6061 aluminum frames are TIG welded using a Syncrowave™ 250 from Miller. Prior to welding, Dobbertin cleans the area to be welded with a stainless steel wire brush. This removes the layer of oxide that forms on aluminum and, if not properly cleaned, can cause impurities in the weldment. The position of the welds, the thickness of the materials and the structural requirements of the frame allow for TIG welding, which gives Dobbertin more control over the weld puddle, tailoring penetration and the aesthetics of the bead to his liking. Filler metal used throughout the welding on the frame and the skin is ER5356 aluminum (3/32- to1/8-in. on the frame, .035 on the skin), suggested for its rigidity and strength compared to other popular aluminum grades such as ER4043.

On the 1/8-in. 5086 skin, however, long TIG welds  would provide too much heat, leading to warping or pulling that could cause both structural and aesthetic deformities. Instead, Dobbertin decided to connect the skin to the frame using simple stitch welds every 6 in. along the seam where the skin meets the 6061 structural frame, then using a marine-grade caulk to provide the rest of the seal.   


"The biggest challenge was welding the frame," recalls Dobbertin. With the Millermatic 251 and the Spoolmatic 30A, "we can keep the warpage down to a minimum and make the skin a part of the frame, without using rivets or screws or bolts or anything like that. It's a really slick way to do it, and the Spoolmatic 30A spool gun is the ticket to success with this project."

Millermatic 251 and Spoolmatic 30

Dobbertin chose the Millermatic 251 based on the reliability of the Millermatic 200 he's had since the 1980s and the Syncrowave 250 he uses for TIG welding.


"I welded my first car in 1982 with the Millermatic 200, and I've only replaced the liner on the gun and tips. But, that's it. Nothing else. If you had luck like that would you ever go to somebody else?  No way."

The Millermatic 251 welds metal 22 ga. to 1/2 in. thick in a single pass and has a 30-to 300-amp output range (250 amps at 40 percent duty cycle). The Millermatic 251's patent-pending Active Arc Stabilizer control and adjustable run-in speed control start the arc more consistently than any comparable machine. It also features Miller's exclusive Gun-on-Demand™ feature for switching instantly between a spool gun and the regular MIG gun.  

For MIG welding aluminum, obtaining good productivity depends on a good wire feeder, and Dobbertin finds the ultimate consistency with the Spoolmatic 30 spool gun. Its design is small enough that he can maneuver the gun throughout the inner frame of the car. It holds a 4-inch diameter spool of wire mounted on the back of the gun and provides superior aluminum wire feeding performance because its drive rolls feed the wire just eight inches, rather than forcing it through 12 ft. of cable, like on a regular MIG gun. This eliminates the potential for "bird's nests," produces a steadier arc, more consistent penetration and reduces the chance for burnbacks(all factors that lead to a strong, sturdy weldment. 

"The Millermatic 251/Spoolmatic 30 combination works super. I haven't had any problems with it," claims Dobbertin. "Its voltage and amperage are infinitely adjustable for fine tuning and it (the power source) features digital settings, which add precision and repeatability."

Considering that most are made on the inside of the frame, Dobbertin welds the skin are in whatever awkward position he can get into. In welding the 1/8-in. skin to the X-in. frame, Dobbertin uses a push gun technique and feeds the .035 wire at 411 inches per minute (IPM) at a setting of 19 volts. Typically recommended for such materials is 20 volts at 400 IPM, but he lays the bead a little cooler to better control warpage and a little faster to better control the quality of the weld. In the overhead position, Dobbertin must apply faster travel speeds to ensure the filler metal stays in the joint and increase the flow of the 100 percent argon shielding gas to XX CFM for optimum gas coverage to prevent weld contamination. It's also important to note that, despite the awkward angles he encounters, Dobbertin keeps his gun travel angle between 5 and 15 degrees. Anything more would increase the amount of splatter.      

"This whole process has been 'learn as I go'," says Dobbertin. "When laying my bead, I concentrated on the heavier frame and let it bleed onto the skin. It worked out really well. It's really solid, and the test pieces show that. We hammered and chiseled on the test pieces and it didn't come apart."

Dobbertin likes the Spoolmatic 30 with his Millermatic 251 because the 30 feet of cord gives him enough length to not only make welds throughout the 20-ft. length and 8 ft. width of the HydroCar, but also because he can jump to another project within his garage without having to move the power source. The spool gun also allows Dobbertin to vary the contact tip-to-nozzle position easily for optimum gas coverage. A built in gas valve eliminates the need to purge gas lines and offers the ability to adjust wire speed at the gun handle instead of at the power source, reducing operator hassle.

"It's a good package," says Dobbertin. "You can see, just from the evolution of the equipment through the years that they (Miller) do their homework and they really listen to the consumer."

Sailing off into the Future

The HydroCar marks the last major project for Dobbertin, who envisions a quieter future to spend more time with his wife and family. The HydroCar, the next of kin to his Orbiter, may just be the crown jewel of his legacy. When finished, the Hydrocar will be Corvette-yellow with a blue racing stripe(a blue that closely resembles the color of his favorite welding equipment that helped him conquer tough welds in tough locations on the innovative HydroCar.

"The Miller equipment always delivers what they say," says Dobbertin. "Actually, they surpass it."

Updated: January 7, 2016
Published: July 1, 2007