Thursday, May 11, 2006

CNC Gantry Milling Machine Reduces Time

Switching to CNC milling has reduced the time needed to cut pool cue points and the female pockets they fit into by 75% to 80%, according to Bill McDaniel, President of McDaniel 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 mill. The new method reduces cutting time, is more accurate and provides unlimited design flexibility.”

McDaniel Custom Cues is one of the best-known manufacturers of cues used by professionals and leading amateur pool players. They include: 1) Kun-Fang Lee, the reigning winner of Challenge of Champions 2) Ismael Paez, also known as Morro, who recently won the European World 9 Ball Championship 3) Nick Varner, winner of the Year 2000 WPA World 9 Ball Championship held in Spain and the Masters Senior Tour held in Florida 4) on the women’s side, Karen Corr, the upcoming number three ranked lady player in the World who recently won the Women’s Pool Billiards Association championship in Valley Forge, Pennsylvania, beating Allison Fisher 7-1 in the finals. McDaniel travels the world seeking out the finest materials for his products, such as Gabon (a region of Africa) ebony, snakewood, tulip wood, birdseye maple, ivory, silver and gold. The firm’s cues sell for $1000 and up.

Challenging task

“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 three days depending on the complexity of the design. This process had to be repeated whenever McDaniel produced a new design, which occurred several times a month.

“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. Even after we were sure that the pattern was right, a considerable amount of tracing skill was required to achieve the required accuracy of a few thousandths. “Using the old method, producing points was a time-consuming task, one where something could easily go wrong and ruin an expensive piece of birdseye maple, ebony, ivory or even gold, “McDaniel said.”

Switching to CNC

“Then one day I visited a woodworking facility building furniture and saw a CNC mill 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.”

“The company was using a CNC mill from Techno-Isel,” McDaniel said. “I took note of the fact that the ball nuts and ball screws on the machine were extremely accurate. I asked them how much it cost and when they told me about $20,000 I knew I had something that would pay for itself in a short period of time. I could have purchased a low-cost mill that uses racks and acme screws for less but it would have been limited to low speeds and shallow cuts and probably would have suffered from vibration that would give unsatisfactory parts. The furniture company also had nothing but good things to say about the service and support for the milling machine provided by its manufacturer. Then I began doing my homework. I made the contact with the factory and was invited to the World Woodworker show that was held in Anaheim, California to see a complete demonstration of their milling machine. I flew to California, met the staff of Techno-Isel, received a warm reception from their staff and the rest is history.”

New process for producing points

The new machine made it possible for McDaniel 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 machine 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. When the time comes to change an existing profile, a typical dimensional change can be made in seconds on the computer as compared to two days to build a new pattern. To provide a final validation step, McDaniel Custom Cues technicians watch a simulation of the toolpath on the computer before the part is cut.

With the design fully validated, the technicians are ready to produce a prototype. This just takes a few minutes, much less than what was needed to prove out a pattern. For each inlay pattern produced, the operator rotates the butt to put another section into position. The time required to produce a cue is about one fourth of what is needed on a pantograph mill. The Techno-Isel machine's .0004 inch resolution and repeatability and 0.003 inch absolute accuracy are considerably better than what craftspersons were able to achieve with power tools. The Techno machine's accuracy is the result of several features inherent to the table. 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 mill 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.

Productivity improves

In approximately 8 years of operation, McDaniel Custom Cues has had no problems with the Techno machine and has never even needed to replace a single part. 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. “Overall this machine has been great for me,” McDaniel said. “I couldn’t have chosen a better machine from a price or accuracy standpoint and the staff at Techno has been great to work with. One of the technical engineers, Roy Valentine, has been absolutely great to work with as he has always been available to answer any questions I had pertaining to their machine’s capabilities. The machine has helped me improve the quality of our cues while saving money. Since then I have purchased a fourth rotary axis for the first machine and a second machine that is performing just as well as the first. I have already discussed purchasing a third machine for a certain specific operation in our factory.”