Sporting Goods

CNC Routers Help Sporting Goods Makers Increase
Accuracy and Reduce Costs

A new generation of CNC routers is helping sporting goods manufacturers to increase accuracy and reduce costs in the production of intricate wood, plastic and composite materials. In the past, manufacturers typically used duplicators or power tools to build complicated components in volumes too low for expensive automated machines. The new routers substantially improve production of these components by duplicating the computer-aided design geometry used to define the part geometry to an accuracy of ±0.1 mm often; this makes it possible to improve the performance of the product by increasing its geometrical complexity. Another aspect of improved performance comes from the ability to make systematic and repeatable modifications to designs to experimentally improve the performance of the product. Yet, the new machines cost as little as $20,000 and can run without operator attention except for setup, which keeps costs low.

McDaniel's Custom Pool Cues

Switching to CNC routing has reduced the time needed to cut pool cue points and the female pockets they fit into by two-thirds, according to Bill McDaniel, President of Custom Cues, a high-end cue manufacturer based in Jackson, Tennessee. "We used to produce inlays and the points themselves working from patterns on a pantograph-type mill," McDaniel said. "Now we design the points in CAD and then cut out both the prongs and the inlay on the router. The new method reduces cutting time, is more accurate and allows us to change designs in less time than before.

"There's nothing about making pool cues that's easy," McDaniel says, "but one of the most challenging tasks is the inlay work." The points, typically 7.5 inches in length, are inlaid around the circumference of the 29 inch long butt. In the past, McDaniel's firm had to make a male pattern for the points themselves and a female pattern for the butt inlay, which took between one and eight hours depending on the complexity of the design. Once the pattern was completed, McDaniel's staff finally had the opportunity to check it against what they were trying to make. Because the process of making the templates provided no opportunity to check for errors, there were sometimes problems with the first one. "Using the old method, producing points was a time-consuming task, one where something could easily go wrong and ruin an expensive piece of birds eye maple". McDaniel said.

"Then one day I visited a woodworking facility building furniture and saw a CNC router at work," McDaniel said. "It was an eye-opening experience. The company used an easy-to-operate CAD system to create their patterns on the computer. Then the router followed the CAD designs to produce the points and the pockets. This saved the time required to build the pattern and also made it possible to produce a much more accurate cut while eliminating the difficult task of following the pattern. Despite the fact that the parts being produced were nothing like pool cues, I felt certain that I could make this technology work in my business."

McDaniel purchased a CNC router from Techno-Isel, New Hyde Park, New York, for about $20,000. The new router made it possible for Custom Cues 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 the CNC programming package that is provided with the Techno router 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. For each inlay pattern produced, the operator rotates the butt to put another section into position. The time required to produce a pool cue is about one third of what is needed on a pantograph mill. In approximately 2000 hours of operation, Custom Cues has had no problems with the router. "Overall this machine has been great for me," McDaniel said. "It has helped me improve the quality of our cues while saving money."

Windsurfing Board Fins

A more efficient airfoil design combined with computerized manufacturing technology is helping professional windsurfer racers improve their performance. High performance windsurfing boards, which are generally 7' 8" to 9' 4" long, operate normally in a planing condition with only the rear one-fourth to one-third of the board touching the water. The only device providing counterforce is a small fixed fin at the rear of the board. The fin operates in much the same manner as an airplane wing. However, unlike the wing of a conventional airplane, the fin must work in both directions. In this respect, it is similar to the function of wings used in certain fighter and aerobatic airplanes that are designed to fly equally well upside down. While racing windsurfing fins have traditionally been designed by trial and error, it occurred to Gerhard Opel, who worked for 14 years as an aeronautical engineer and is also a board sailor, that optimized airfoil designs which have been developed for aircraft could be transferred to sailboard fins with little or no modification.

The problem in implementing this idea was how to produce these airfoil designs to the required high level of accuracy. Fins for mass produced windsurfing boards are produced from injection molded plastic. These fins are not used for high-performance boards because the injection molded fins change their shape slightly as they cool. Fins for high performance boards are traditionally produced by far more expensive manual methods. An experienced craftsman begins by building a series of templates that describe the contours of the fin. The craftsman then uses these templates as guides in producing the final form with a hand grinder. It typically takes about a day to make a high performance fin. The accuracy of this approach leaves much to be desired so it is necessary to test the fins in the water to determine whether or not  they are effective. A top name competitor will typically accept 2 out of 10 fins produced by these methods.

When Opel originally developed the idea of building fins according to optimized aerodynamic profiles, he assumed that it would be necessary to build them using conventional manual techniques. It was no secret that much greater accuracy could be achieved with CNC machining;

but this alternative was not given serious consideration because it was assumed that the machinery and software required to implement this technology would cost at least $100,000. Unfortunately, the market for fins for high performance sailboards is not large enough to justify this expenditure. A Techno CNC router makes it possible to produce fins to precise aerodynamic profiles at a cost that is less than the cost of hand-producing high performance fins. It takes about 4 hours to produce each fin. Many races have been won with fins produced by this method. Anders Bringdahl is only one of the well-known racers that have used the fins to beat their best previous times.

America's Cup Yacht Rudders

CNC milling of a foam blank for an America's cup rudder
blade at Goetz Marine Technology.

America's Cup boats are getting faster all the time, and part of that is due to Goetz Marine Technology's (GMT) use of Techno CNC routers to produce the precisely shaped, perfectly symmetrical composite rudders many of these boats use. Boat designers try to optimize the rudder design to provide maximum speed and lift, so symmetry and accuracy are critical in the production of the rudder. In the traditional manual production process, the blade's foam core was manually carved, one half at a time. Templates representing the blade half were inserted into slots cut in the foam blank. The foam was then carved with a power plane down to the tops of the templates. After one side was carved, carbon fiber was placed on that side and allowed to set. The next day, the piece was flipped over so the other half could be carved. It too was covered with carbon fiber and once it hardened, the two halves were joined. The drawback to this method was that because the foam core was cut by hand, accuracy was only possible to about four or five mm. This approach was also somewhat slow, taking about 16 hours to produce a part.

Now after GMT receives instructions from a yacht designer, the rudder production process proceeds this way. First, an engineer recreates the blade in a software program called KeelCAM that was created specifically for modeling foil-shaped objects. The smoothed blade produced by KeelCAM becomes the cutting file for the Techno router. The data describing the plan form of rudder blade is transferred into the machine's Mac100 controller. The carving stroke is in the fore and aft direction. Most rudders can be carved in three 40-inch cutting sessions. Compared to the 16 hours required by the manual approach, this is a beneficial time savings, but the real benefit of the automated method is that GMT is now delivering blades with 1/2 mm accuracy. The more accurate rudders produced by this method can significantly increase the speed of the yachts.

Exercise Machines

The Gyrotonics Expansion System

A well-known Yoga instructor helped express his artistic talent at a commercial level by turning a new exercise machine concept into a profitable business with the help of a CNC router. The new concept involves wooden, multipurpose exercise machines that are designed to simulate the movements used in ballet, swimming, gymnastics and yoga. Horvath's machines incorporate the kind of sweeping organic curves one expects to find in Art Noveau furniture. The platforms are carved in the Santa Cruz style of wavy red and blond woodwork and patterned after the swirling shapes of bonsai trees. They are created to command a "melodic movement" that increases the individual's effective range of motion. These sweeping, circular movements involve the whole body at once, building strength without adding bulk. Horvath's machines emphasize the articulation of the joints and strengthening of the surrounding ligaments in such a way that it makes the connection between the bones much stronger.

The base and support elements are made of wood while other components are machined aluminum. In the beginning, Horvath built wooden components with a jig saw using intricate templates to guide his hands, and heavily sanded each piece after cutting. There were two problems with this approach. It took so long to build each machine that, considering his other time commitments, Horvath was precluded from turning the exercise machines into a serious business. Second, the lack of precision provided by jigsaw cutting meant that the components of each machine had to be individually fitted. Each machine took so long to build by this approach that it seemed impossible to build a profitable business from his conception. Horvath builds each machine himself and this is a key selling feature of the equipment.

Several years ago, however, Horvath switched to a computerized router that has allowed him to cut the time required to build the machines by 80% and turn what was previously merely a labor of love into a going concern. The router was relatively inexpensive. Horvath estimates that he paid for its cost last year in one single order for five machines. Horvath himself is computer illiterate, but he has a friend who converts his sketches into AutoCAD drawings then uses a CNC programming package called Mastercam® from CNC Software, Tolland, Connecticut, to produce a file that the router understands. Once the program is finished, Horvath operates the machine in his workshop. When he wants to produce a part, he simply loads a piece of wood and pushes a few buttons to start the router. He does nearly all the manufacturing work himself although he does use part-time employees from time to time.

The CNC router concept is clearly an idea whose time has come in the sporting goods business. It makes it possible to improve the performance of many sporting goods products by allowing complex geometries to be produced to a high level of accuracy. The high level of repeatability and accuracy also allows for systematic changes and experiments to be performed to improve product performance. At the same time, manufacturing costs are reduced because of the elimination of time-consuming handwork. Best of all, the new routers are available at a fraction of the cost of traditional CNC machining equipment.