89MECHANICAL STRUCTURE 11Main Control Knob MechanismThe main control knob is made of aluminum that is NC-machined.Its shape was designed by taking into account the rotational balance and suppression of eccentricity. The design resultsin a superb operational feeling of a weighted, smooth, and accurate touch. The surface of the main knob is machined bya specially-designed tool bit and is finished so that it has a radially lucent spin-cut pattern.The torque adjustment ring, which is placed on the main knob shaft, is made of aluminum die-cast. Uncompromisingattention was also given to the texture of the main knob.Main KnobRing KnobFig. 95 Appearance of the Main KnobThe rotation mechanism of the torque adjustment ring employs a coated metal plate in its slider block, which securesbetter clicks, smoother rotation, and longer durability.Furthermore, its friction material is carefully chosen for better torque adjustment. An aluminum sheet is used for thesurface of the arm on the main knob side and artificial leather is used for the friction material on the opposite side toreduce rotation noise and ensure smooth rotation.Metal PlateTorque-increase ArmFig. 96 Inside the Torque Adjustment Ring
