By Jay Bouxsein
President
Unique Woodworking & Carving Inc.
Elk Grove Village, Illinois

Unique Woodworking & Carving offers standard and custom factory-direct millwork. Its primary market is custom-built homes, and its products are sold to architects and builders primarily. The standard product line includes bases, cases, crowns, moldings, dentils, blocks, chair rails, and trim. The company produces a variety of custom woodwork, such as crown molding and chair rail carved with a customer's unique pattern, doors, display cases, and so on. Often their custom pieces are used in restorations where the builder is trying to match a style or molding pattern from the original structure. A recent job for a Chicago hotel restoration, for example, involved making a conference table, large display case, and doors in the hotel's original mission style. Unique Woodworking mills products from the more common woods such as oak and poplar but also works in mahogany, bloodwood, satinwood, silky oak, and other exotic woods.

About two years ago, Unique Woodworking realized that with custom orders and 3D patterns being a growing part of its business, it made sense to look into computer technology that could automate the time-consuming aspects of this work and reduce its cost. Carving a pattern on crown molding or chair rail, for example, offers a distinctive look that many people would like to have. But carving by hand takes so long that it prices the product out of most people's reach. With a CNC (computer numeric controlled) router, they hoped to be able to carve the pattern much faster and thus, less expensively, driving the price down to where more people could afford it.

The Techno machine's ability to perfectly replicate previous cuts assures that components created today match those created earlier.

The search for a CNC machine began with requests for literature from a variety of manufacturers. The company got information about several machines in the $35,000 to $60,000 range but felt these were too expensive for their current volume of work. Then they heard about the Techno Series III PC-driven CNC wood router which costs less than $16,000 and is designed for production routing and drilling on a wide variety of materials including wood, plastic, MDF, solid surfacing materials, and nonferrous metals. The price included the CNC programming system, which has the ability to generate complex contours with little programming effort. The system features true 3D geometry construction plus IGES, DXF, and CADL converters so that geometry can be uploaded from nearly any CAD system, including Unique Woodworking's TurboCAD program. The combination of capabilities included in the Techno CNC system and the price seemed perfect for the Unique Woodworking's needs, so the company purchased it in 1996.

Since installing the Techno machine, Unique Woodworking has been able to attract more custom work because the company is able to charge set-up fees that are about half those charged by other woodworking shops. Custom jobs involve a set-up charge because the shop must create new knives for the milling machine, which cuts the linear profile of the piece. The knives are ground out of high-speed steel by following a template made of plastic. Unique Woodworking now saves several hours of set-up time by producing the templates on its Techno system. The pattern for the knives is modeled in TurboCAD, then exported to the CNC programing system. There the user specifies the cutting tool, the cutter size, tolerance, feeds, and speeds and the software generates the toolpath for the router. The Techno machine cuts plastic templates faster than anyone can cut them by hand.

Another part of the set-up involves adjusting the milling machine, which has seven milling heads. This involves installing the new knives, setting feeds and speeds, and altering sensors for each milling head to accommodate the new pattern. The entire process can be time-consuming, which accounts for some of the set-up charge. Unique Woodworking's milling machine features computer-assisted set-up, however, which also saves some time. Between this and the faster production of knife templates, Unique Woodworking can keep its set-up fees in the $150 to $300 range.

The Techno machine also results in more accurate knives because it cuts the templates more accurately than possible by hand. The machine has a positioning accuracy of +1 mm in 300 mm and a repeatability of 0.01 mm. It has anti-backlash ball screws for play-free motion. These screws have excellent power transmission due to the rolling ball contract between the nut and screws. This type of contact ensures low friction, low wear, and long life. The ball screws also make it possible to produce wooden parts to the machine resolution of 0.0005 inch. That level of accuracy is actually much greater than what is needed for woodworking, but the improvement over what can be done by hand is important, especially in restoration jobs where new molding is being cut to match existing pieces. The accuracy of the templates produced with the Techno machine ensures highly accurate knives, which in turn ensures a good match between the new and the old woodwork. Every bit as important as the machine's high accuracy is its repeatability. In commercial woodworking parts often have to match and/or fit together with previously made parts. The Techno machine's ability to perfectly replicate previous cuts assures that components created today match those created earlier. Since installing the CNC machine Unique Woodworking has not had any millwork returned because it didn't match the pattern requested by the customer.

The accuracy provided by the CNC machine has come in handy on other tasks besides cutting knife templates. The mission-style display case for the Chicago hotel was 12 feet wide and 8 feet tall and had mullions that ran all the way across to hold double-thick glass. Unique Woodworking used the CNC machine to cut the mortises for the mullions to make sure there would be no assembly problems. The conference table for the hotel, also done in mission style, had rails and styles in the design. Twelve styles had to be centered between two leg members. That demanded accurate placement of them about 5/8-inch apart. Placing them this accurately would have been difficult to do by hand. By using CAD to lay out the placement of the styles and the CNC machine to cut the mortises for the styles, accuracy was ensured.

Unique Woodworking produces a variety of custom woodwork, such as crown molding and chair rail carved with a customer's unique pattern, doors, display cases, and so on.

The technical specifications of the Techno machine include a working area for the router of 49 inches by 41 inches and z-axis height options from 4 to 19 inches. The table features a rapid travel rate of 300 inches per minute, a z-axis cutting force of 200 pounds maximum, 0.0005 inch resolution and repeatability, and 0.003 inches /foot absolute accuracy. A key feature of the Techno machine is its ability to cut 3D continuous contours at up to 200 inches per minute, far faster than most machining centers.

Although Unique Woodworking currently uses the machine primarily for custom work and, on a limited basis, production work, they foresee a time when it will be used primarily for production work. The company has programmed the machine to cut a number of 3D patterns into chair rail and crown molding. These are now offered as standard items in the company's catalog. Company officials are hoping that, with some promotion, these carved pieces will become popular. If that happens, the company will use the Techno machine in production mode. The linear profile of the pieces will be cut on the milling machine and the 3D profiles will be cut on the CNC machine, as is done now for custom jobs.