The power saws traditionally used to cut roof-truss components have up to 20 axes of motion, waste time between setups, and generate tons of scrap. Engineers at Alpine Engineering Products, Grand Prairie, Tex. (www.alpeng.com), have developed a simpler and more-productive saw dedicated to making truss components. The new Alpine Linear Saw is basically a six-axis CNC machine with a control system engineered by Minarik Corp., Plano, Tex. (www.minarikcorp.com). It uses two axes to load, feed, and eject lumber, which can be anywhere from a 2 X 3 to 2 X 14 stock, at up to 58 ips. Two other axes cut angles and bevels. The final two axes are translational and vertical. The translational lets cuts be made in the center of other cuts and lets the saw make extremely long cuts via electronic gearing. The vertical axis raises and lowers the saw, angle motor, and bevel motor and can be electronically geared to the feed and translation servos to perfom compound angle cuts.

The motion controller is a Sercos-based Kollmorgen MC. It sends positional commands to brushless servomotors across an optical network at 4 or 8 Mbps. It replaces PLCs and inverter drives. Servo technology was needed to handle the saw's high forces and meet the need for speed and precision. Servos also detect faults in the electronic system and report them to the operator.

Each of the six axes uses a Kollmorgen MT Series 1.5-kW motor, except the vertical axis, which relies on an Exlar Satellite roller-screw motor. But each motor has a resolver that sends data to the drives which, in turn, send position data via Sercos back to the motion controller. The drives handle tasks such as closing torque, velocity, and position loops based on position data from the Kollmorgen MC.

The machine handles all standard truss cuts. There are just a few cuts, such as the bird's mouth (notch in edge), the machine cannot do. Competing saws only do simple cuts on 2 X 4 stock, and will not do compound bevels or long scarfs.