Straddle Milling Cutters is cylindrical in form and is used for milling flat surfaces. Cutters having helical teeth are generally used in preference to the type with straight or parallel teeth, especially for milling comparatively wide surfaces because the former cut more smoothly.
Bevel gears are conical in shape. The teeth are tapered in both tooth thickness and tooth height. At one end of the tooth is large, while at the other end it is small. The tooth dimensions are usually specified for the large end of the tooth. However, in calculating bearing loads, the central-section dimensions and forces are used. The simplest type of bevel gear is the straight bevel gear. These gears are commonly used for transmitting power between intersecting shafts. Usually the shaft angle is 90 degree, but it may be almost any angle. The gears impose both radial and thrust load on their bearings. In straight bevel gears the teeth are straight and parallel to the generators of the cone. This is the simplest form of bevel gear. It resembles a spur gear, only conical rather than cylindrical. The gears in the floodgate picture are straight bevel gears. In straight, when each tooth engages it impacts the corresponding tooth and simply curving the gear teeth can solve the problem.