Kicking into high gear

Jan. 1, 2002
CAD/CAM technology propels scooters from prototype to production at record speed.

CAD/CAM technology propels scooters from prototype to production at record speed.

Nova Cruz makes the Xootr Scooter, an adult-oriented kick scooter. "There's really no comparison between Xootr Scooter and most other kick scooters," offers Karl Ulrich, co-founder and CEO. "Largely, kick scooters are designed for children. Ours is larger, stronger, and better engineered. The toy scooters run on inline skate wheels. Our wheels are two times larger and made with exotic, low-hysteresis polyurethane to minimize rolling resistance."

Cut Part Rendering shows the Xootr name being machined into the aluminum deck.

Machine Operator Brett Guldbrandsen sets up a pilot production run of parts for the Xootr eX3.

These motor shafts for the new Xootr eX3 electric scooter were cut on a Cincinnati Hawk 200 CNC turning center from heat-treated 4140 alloy steel.

Generally, manufacturers make prototypes in small lots, then move to mass production. But not scooter manufacturer Nova Cruz Products of Dover, N.H. Foregoing these more traditional approaches to design and manufacturing, the company instead runs small lots, usually 100 scooters at a time, to fine-tune its products and solicit customer response. Improving a design in reaction to feedback from the market, believes Nova Cruz, is better than waiting until the next product cycle.

"We move from prototyping to production still using what are considered more expensive processes, like CNC machining," says Nathan Ulrich, chief technical officer. "We'd save money by making castings to produce moldings, but we wait because we want to hear from our customers."

CAD/CAM software makes this quick-reaction mindset possible at Nova Cruz. All design work and part programming are done by Ul-rich and two other engineers using a CAD system from SolidWorks Corp., Concord, Mass. They then generate CNC programs with GibbsCAM SolidSurfacer from Gibbs and Associates of Moor-park, Calif.

Nova Cruz's agile-development philosophy has optimized production for such products as the Xootr eX3 electrically powered scooter. The company designed and built prototypes for the electric model in a couple of weeks and introduced design changes into the production parts in just days.

For instance, Ulrich designed a new handlebar clamp component in just a day. Using an existing part geometry and SolidWorks, he produced a solid rendering of the part in about two hours. He then assem-bled the solid with other CAD parts to ensure fit, imported the SolidWorks solid geometry into GibbsCAM, and extracted the geometry needed for the toolpath. He designed, set up, and programmed all operations before noon, and after lunch, he cut a test piece, set up the machine, and transferred the NC file over the ethernet.

According to Ulrich, Nova Cruz typically has the first five prototypes of a standard part in a half day or so. Difficult parts, though, can take several days to produce.

Design changes are also quick, claims Ulrich. Using an operation summary generated by GibbsCAM, he found it took 42 sec to machine a certain feature with a 1 / 4-in. end mill. He wanted to reduce that by changing the feature to use a

"I tried a design change in SolidWorks and imported it into GibbsCAM, which showed I could cut machine time by about 60%," he comments. Armed with this knowledge, Ulrich ran a test part, and within a half hour, he had given his crew an order to run 50 parts. "I did all this in four hours — changed the design of the part to reduce machining time, machined the prototype, and introduced it into the production process," he explains. "That four hours, in a conventional organization, could be four months."

Its clever use of technology keeps Nova Cruz scooting along in a competitive market, where most scooters are made in the Far East. "Our parts are made in the United States," says Ulrich, "so the cost for our assembly labor is higher than that of our competitors in Asia. For example, they can afford to do labor-intensive fabrication, welding, and hand finishing. We can't."

Ulrich credits the SolidWorks/ GibbsCAM combination for streamlining Nova Cruz's prototyping and parts production. "Also, through our CAM programming, we're getting the most efficient use of our in-house CNC machining capabilities," says Ulrich. "In many cases, our product never leaves the factory for outside machining. That's important, and not just as a cost-control measure, but for quality control."

The GibbsCAM software proved a match for Ulrich's needs and for his design software. Compatible with most CAD software, GibbsCAM is particularly well suited to the Parasolid-based SolidWorks, since it directly reads SolidWorks's model files and creates machine programming from them. Designs, including solids, move seamlessly into the CAM software, where its Solid-Surfacer feature gives Nova Cruz 3D virtual-milling capabilities.

But wouldn't any CAM program do the same thing? Ulrich doesn't think so, having conducted an extensive search for CNC programming software. With GibbsCAM, recalls Ulrich, "I machined my first parts that afternoon. I had always been a designer who sent a drawing to a CNC shop, and I had never programmed a machine tool."

Ulrich also believes the power of GibbsCAM is as good, if not better, than other CAM systems. He points to how GibbsCAM handles complex surfacing of machine molds for Nova Cruz's variety of composite, carbon-fiber, and Fiberglas parts. "Complex surfacing is a good test of any CAM system," explains Ul-rich. "With GibbsCAM, I've called Gibbs for help with one problem mold — maybe two — out of more than a hundred. It's a powerful tool, as well as being easy to use."

An electric start

Nova Cruz designed and built prototypes for the eX3 electrically powered scooter in just weeks with its CAD/CAM technology.

"We think that electric scooters are going to enjoy growth in the coming product year, similar to that of kick scooters last year," says Karl Ul-rich. In preparation for that possibility, Nova Cruz is launching the eX3 electric scooter.

Where most, and perhaps all, competitive products are run on lead-acid batteries, the Xootr Scooter eX3 employs nickel-metal-hydride batteries that are lighter and more efficient. "The eX3 is the lightest electric scooter you can buy," says Nathan Ulrich. "Others weigh 35 to 38 lb. Ours weighs 20 lb."

The eX3 is powered by a brushless electric motor that lets the scooter accelerate to 12 mph in just 5 sec and powers an adult rider up a 10% grade. The maximum cruising speed of the eX3 is 17 mph. "Our product has half the weight, twice the speed, and twice the hill-climbing ability as the competition," states Nathan.

Unlike most electric scooters, the eX3 features a variable-speed throttle and regenerative braking. The regenerative brake employs a special motor-control scheme that recharges the batteries while slowing the scooter.

The scooter goes 16 miles on a single charge, and it can be ridden as a kick scooter when not powered. Its small size and light weight let it stow easily in a car trunk or be carried on public transportation.

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