By Rick Dodge
President
Dodge Guitar Company
Tallahassee, Florida

Switching from power tools to a CNC router helped us reduce the time required to develop new guitars from two months to two days. Reducing product development time has made the company more profitable and made it possible to introduce products for smaller market niches that would have been too expensive to address in the past. It used to take two weeks to build the prototype for a new guitar with most of the time being occupied in building templates. Problems with the initial design were always discovered, which required a long iterative process that involved making up to a dozen prototypes to resolve. A new CNC router dramatically streamlines this process by allowing us to develop electronic prototypes in which we can check the fit of critical components. As soon as we have completed our design on a personal computer, the machine produces the guitar without the need to make templates, saving huge amounts of time.

Dodge Guitars has developed a patented modular system that allows the player to replace all of the electronic components of the guitar in seconds, providing unlimited sound possibilities. They can switch from a three single coil Stratocaster configuration to a twin single coil Telecaster setup to a dual humbucker Les Paul configuration, all in the same guitar, in a matter of seconds. Each interchangeable module contains the complete electronics for the guitar, including pickups, switches, knobs and jacks. Active electronics or any specialty pickup combination, including MIDI wiring, can be incorporated into a module. The sustain is comparable to any other well-crafted electric guitar.

Challenge of a modular system

Building a modular guitar represents a considerable challenge from a design standpoint. The module, a hollow box that inserts through the back of the guitar, must be perfectly aligned with the guitar strings in order to provide the proper sound. Insuring that this level of accuracy is achieved with every module is a challenging task. In the past, when the company used power tools to build its guitars, it was very difficult to establish the proper relationships between the different components. Building a prototype first required that about a dozen separate templates be created to produce the front and back of the guitar body, the neck, and other parts. Producing all these templates and building the prototype took about two weeks with a power router with a bearing bit.

Once the prototype was completed, we finally had the opportunity to check it against what we were trying to make. Because the process of making the templates provided no opportunity to check for errors, there were always a considerable number of problems with the first one. For each problem we had to create a new template and often a problem affected more than one template. It was necessary to build an average of 10 prototypes before we achieved the demanding levels of dimensional performance required to achieve management approval to begin production. The amount of time involved in developing new products meant that we could only address relatively large market niches where they were certain that sales volume would be high enough to pay back the development costs.

Search for an alternative

In an effort to develop products faster and at a lower cost, Dodge Guitar management investigated various computerized numerical control (CNC) cutting tools. The goal was to create and validate the design on the computer in order to eliminate or at least streamline the lengthy prototyping process. At first, we considered a traditional CNC machine. These machines, made by companies such as Bridgeport, start at $50,000, not including the CNC programming software. To get a model with a large-enough working area, Dodge Guitar would have had to buy one of the larger machines costing at least twice that. Another alternative would have been a low-cost router that uses racks, acme screws and stepper motors but it would have been limited to low speeds and shallow cuts and probably would have suffered from vibration that would hurt part finish. Then they heard about a new type of gantry router that has a large cutting area and most of the features of much more expensive machines such as ball screws, servo motors and a heavy frame yet was still available at a low price.The supplier of the Techno Series III, Techno-Isel, New Hyde Park, New York, has been around for longer than any of the other low-cost router manufacturers and managers heard they had a good reputation for service and support. Dodge Guitars ended up purchasing the machine from their local dealer, CWS Associates, Inc., Newport Richey, Florida. The price was less than $26,000 including CNC programming software. Its working area of 40 inches by 48 inches with a Z-axis height of 6 inches is large enough to set up multiple guitars at once.

The new machine made it possible for Dodge to adopt an entirely new approach to new product development. Now, the firm’s engineers begin the design process by using the computer aided design (CAD) capabilities of Mastercam to sketch out their design on the computer in three dimensions. By manipulating their model on the screen, panning, zooming and rotating, they are usually able to validate all critical dimensional relationships before they even begin to cut wood. In their most recent project, a new bass guitar, for example, they digitized an existing guitar body, then made about 50 changes to their original design on the computer prior to building the prototype. The best feature of the new approach is that a typical dimensional change can be made in two minutes on the computer as compared to half a day to build an accurate template. To provide a final validation step, they put a marker in the machine spindle and used it to trace the outline of the program on posterboard.

Cutting prototype in an hour or two

With the design fully validated, we were ready to produce the prototype. Note that there was no need to make templates first, so it only took an hour or two to cut out the pieces for a prototype. The Techno machine's .0002 inch resolution and repeatability and 0.003 inch absolute accuracy are considerably better than what Dodge’s craftspersons were able to achieve with power tools. The Techno machine's accuracy is the result of several features inherent to the table, such as the use of ball screws and servo motors. For example, anti-backlash ball nuts permit play-free motion that makes it possible to produce accurate curves and inlays and a terrific finish. The Techno router uses ballscrews that ensure longer life and greater rigidity during the life of the system because of the reduced wear as compared to ACME screws and nuts or rack and pinion systems. Cut quality and longevity were important considerations.

Dodge also found that all the big expensive routers used the same ballscrews and servo motor design found on the Techno machines; but none of the expensive routers offered stepper motor drives. Prototypes produced by the new machine generally have few if any problems that need to be ironed out because of the advance validation process performed on the computer. Any changes that do need to be made can be done far more quickly than in the past. The engineer simply enters the change in the three dimensional Mastercam model, then cuts a new part. In the new bass guitar described earlier, only a few minor changes were required to the initial prototype. This made it possible to complete the entire design process in only two days.

Product variants

One of the greatest benefits of the new approach comes after the initial design is complete. Because the design is produced in electronic format and the modeling process is largely automated, it’s easy to modify the design either as an improvement or to create a product variant. In the past, on the other hand, the amount of time required to make changes was high because templates had to be built from scratch. For example, Dodge Guitars recently developed a new line of left-handed guitars simply by producing mirror images of the computer models of existing guitars. Left handed guitars are normally more expensive and there are few choices available. The new CNC approach will let us offer any guitars we wish in left-handed models.

In approximately 300 hours of operation, Dodge Guitars has had no problems with the Techno machine. This is partly due to the strength and rigidity of the table, which is constructed from extruded aluminum profiles that provide easy clamping capability. The machine also has four ground and hardened steel shafts and eight recirculating bearings in each axis. This shaft and bearing system produces very smooth play-free motion and an extremely rigid system that produces high-quality cuts.

As a relatively new entrant to the guitar market, the CNC router has had a big impact on our ability to compete with the market leaders. It has helped us develop an extensive product line at a reasonable cost and allows us to produce a product that matches or exceeds all other products in terms of accuracy and repeatability.

For more information contact: Techno, Inc., 2101 Jericho Turnpike, New Hyde Park, NY 11040.
Phone: 516-328-3970 Fax: 516-358-2576 E-mail: TECHNO CNC ROUTER SYSTEMS

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