issue: September 2003 APPLIANCE Magazine Engineering Power Tools Power Routing	Share  Printable format  Email this Article  Search
When engineers at DeWalt in Towson, MD, U.S. began the design process for its line of routers, the goal was to go beyond just improving an existing product.

Starting from a clean sheet of paper, the company developed a new, feature-rich router platform with enhancements to satisfy the professional woodworker. From the reviews that have been written, it looks like the new design hit the mark and is well on its way to becoming a major success.

As the new DeWalt DW616 and DW618 routers hit stores, both amateur and professional woodworking buffs concur that the new routers clearly stand out from previous models. The major change involved shifting DeWalt's design to a modular system that allows easy interchanging of the router base, motor, and accessories to fit the task at hand. Designers added more user-friendliness to the router by integrating a detachable cord set, soft-start motor, and ergonomically placed controls. These features and more are rolled into a single product that the manufacturer says will please seasoned wood workers with a superior, more flexible product while at the same time enticing the next generation of handy men with a new, easier to use tool.

One of the important innovations resulting from the redesign was the power cord. In the past, power cords could be cumbersome when using a router, particularly when switching between router bases, or when the power cord was accidentally damaged. The new DeWalt router incorporates a detachable power cord set that was a collaboration of DeWalt engineers, cable subcontractor Volex Power Cord Products (Indianapolis, IN, U.S.), and connector manufacturer Tyco Electronics of Harrisburg, PA, U.S.

The DeWalt team wanted the power cord design to accommodate its modular concept and interchange between all the new models. Additionally, since routers generally require more cord replacements over their useful life than other power tools, DeWalt needed a robust, but manageable connection to the router. For convenience and ergonomics, designers wanted to offer several cord lengths so the router could be easily switched between standard, plunge, and D-handle bases.

"Normally, if one buys a competitive D-handle router, it comes with a short - approximately 12-in - cord set that works well only with that D-handle base," explains Jeff Grant, design manager, DeWalt Power Tools. "If one buys a fixed base router, it comes with a 10-ft cord set. Using the same powerhead in the D-handle base can result in having to wrap 10 ft of power cord around the base before it is plugged into the D-base to allow the user to use the trigger switch." With the new interconnect system, craftsmen no longer need to bundle up excess cord when using a D-handle base since an appropriately sized pigtail interconnect is integral to the D-handle. Above all, this robust, versatile cord would need to be very simple, easily attached, and reliable.

The joint design effort required close coordination between DeWalt, Volex, and Tyco Electronics so that the design objectives were met, while at the same time, making sure that the design was efficiently manufacturable. During the conceptual phase, the use of ProEngineer, Stereolithography models, and CAD model exchange proved invaluable in refining the design requirements. Once the conceptual design phase was over, the three companies were able to move quickly into the prototyping phase, and within 12 weeks of approving the design, Volex and Tyco Electronics were able to produce the hard-tooled components of the new cord and connector.

Early in the design definition phase, Tyco Electronics' development engineers began the process by looking at potential connector contacts. The initial evaluation of the application requirements received from DeWalt engineering indicated that the contacts had to be robust and suitable for use over the life of the power tool. With literally thousands of existing contact designs at their disposal, as well as the option to design one from scratch, the Tyco Electronics engineering team finally selected the .140 MATE-N-LOK® contact. The contacts provide a cost-effective interconnect solution that meets the current carrying and performance requirements for DeWalt's new router application. Manufacturability was also addressed with the MATE-N-LOK contacts, as they are available in reel form, which allows the contacts to be applied using a wide range of high-speed, semi-automatic, and automatic termination equipment. Furthermore, since Volex engineers were already tooled up to produce harnesses with MATE-N-LOK contacts using its existing AMP-O-LECTRIC® Model G Presses, they would not have to learn a new production method or invest heavily in specialized tooling.

Now that there was a contact to work around, Tyco could design a housing to package the contacts. To keep the connection simple, Tyco proposed a connector design that is based upon a quarter-turn locking mechanism that is being used in another connector family. To connect the cord, users simply plug it into the router and twist a locking ring 90 degrees to securely lock it into place. The cord-side locking ring was designed to snap around the contact housing and also provide a firm gripping surface that was easy to handle and lock into the router. An overmolded strain relief that keys into the contact housing bolsters the already beefy connector housing and provides additional cord protection and support.

With the contact and housing now developed, Volex, Tyco Electronics, and DeWalt electronically exchanged design models to check that the connector fit into DeWalt's router model and aid in the design of the overmold tooling required for the cord set. According to Mr. Grant, the biggest challenge was keeping the design as small and unobtrusive as possible while maintaining durability. As it turns out, the first try was close, but some minor design changes were required to provide additional component clearance within the router.

After a few iterations and file exchanges, the design was firm enough that SLA models could be generated. Tyco Electronics created SLA models of the connector housings and shipped them off to DeWalt. These parts enabled DeWalt to integrate the connector SLAs with its router model to review the aesthetics and fit of the router prototypes.

It was quickly discovered during the assembly of the model that the contact housing inserted into the router housing would need additional keying to avert problems on the assembly line. In this manner, the models proved their value by identifying assembly issues early in the design cycle where they could be easily (and inexpensively) addressed.

Shortly thereafter, the design was finalized and the decision was made to begin building the production molds for the components. Twelve weeks later, the initial parts were in-hand and after some minor conditioning, the molds were ready to begin producing production components.

The new router looks to be a hit in the industry. The development process that it required, which involved the close collaboration of three companies, was a good example of how the use of CAD and rapid prototyping can quickly refine a design and help bring it to market more quickly. By utilizing these tools and the constant communications between these three companies, the resulting product was destined to be a technical success.