base circle appears on the profile. This is continuous with a tangent to the tip circle. In designing the cam, the lift and the dwell angle are given. If the profile is treated as a large base circle and a small tip circle, joined by a common tangent, giving lift , the relationship can be calculated, given the angle between one tangent and the axis of symmetry ( being ), while is the distance between the centres of the circles (required), and is the radius of the base (given) and that of the tip circle (required): and Disc or plate cam The most commonly used cam is the cam plate (also known as disc cam or radial cam) which is cut out of a piece of flat metal or plate. Here, the follower moves in a plane perpendicular to the axis of rotation of the camshaft. Several key terms are relevant in such a construction of plate cams: base circle, prime circle (with radius equal to the sum of the follower radius and the base circle radius), pitch curve which is the radial curve traced out by applying the radial displacements away from the prime circle across all angles, and the lobe separation angle (LSA – the angle between two adjacent intake and exhaust cam lobes). The base circle is the smallest circle that can be drawn to the cam profile. A once common, but now outdated, application of this type of cam was automatic machine tool programming cams. Each tool movement or operation was controlled directly by one or more cams. Instructions for producing programming cams and cam generation data for the most common makes of machine, were included in engineering references well into the modern CNC era. This type of cam is used in many simple electromechanical appliances controllers, such as dishwashers and clothes washing machines, to actuate mechanical switches that control the various parts. Cylindrical cam A cylindrical cam or barrel cam is a cam in which the follower rides on the surface of a cylinder. In the most common type, the follower rides in a groove cut into the surface of a cylinder. These cams are principally used to convert rotational motion to linear motion parallel to the rotational axis of the cylinder. A cylinder may have several grooves cut into the surface and drive several followers. Cylindrical cams can provide motions that involve more than