Solid wood tends to bend during drying and when absorbing moisture. This bending is also called bowling. The wider a component made of solid wood is, the stronger the bowling effect.
To counteract this, solid wood components are not made from a single piece of wood, but are glued together from individual lamellas. The lamellas are aligned in such a way that the core side and the outside of the wood alternate. In this way, the bowl of the individual lamellas balances each other out. Stair stringers and steps are also glued in this way.
The next step in staircase production is therefore to cut the wood lengthwise into evenly wide lamellas. A rip saw is used for this. This machine works according to the principle of a pressure beam saw: the plank is aligned. To simplify this, a laser projects the course of the saw cut onto the wood surface. As soon as the position is correct, a pressure beam moves down onto the wood plank from above and holds it in place along its entire length. From below, a saw carriage then moves longitudinally through the wood and cuts it in one step. The pressure beam has a double-walled design; inside the beam there is a suction device which removes the sawdust.
Rip saws for solid wood are specially designed for this application. The maximum workpiece length and width is adapted to the shape of commercially available wooden planks. The construction is robust, as the forces occurring during the processing of solid wood are considerable. Thick hardwood planks, such as those used in staircase construction, sometimes have high internal stresses that must be overcome by the saw.
