A rip saw is a wood saw that is specially designed for making a rip cut, a cut made parallel to the direction of the wood grain The cutting edge of each tooth has a flat front edge and it is angled backward by about 8°, in contrast to a crosscut saw, which has teeth angled backward by about 15°. Another difference from the crosscut saw is that the edges are sharpened at right angles to the cutting plane, forming chisel-like cutting surfaces, whereas the crosscut saw is sharpened at an angle, so that each tooth has a knife-like cutting point in contact with the wood. This design keeps the saw from following grain lines, which could curve the path of the saw: by acting like a chisel, the saw can more easily cut across deviating grain lines, which is necessary if a straight cut is to be achieved. This feature enables the orthogonal cutting edge to efficiently transport wood-chips from the kerf, allowing subsequent teeth to perform a more effective cut. It is possible to see this material removal mechanism in action by analyzing frame by frame footage of the cutting process. Rip saws typically have 4-10 teeth per inch, making them relatively coarse.