A rotor and cage assembly includes a skeleton of curved spaced-apart side members affixed to laterally extending upper and lower spaced-apart members therebetween and surrounding the rotor. One of the curved spaced-apartside members is terminated with curved fingers. Three concave inserts insert laterally into the skeleton spanning 270° around the rotor. One of the concave inserts carries straight fingers that interlace between the skeleton side member curved fingers. A control assembly of plates having arcuate slots placed at 3 of the pivots of the skeleton assembly, control bars connected to the skeleton pivots, and an actuator connect to the control bars at one end effect arcuate rotation of the control bars resulting in the synchronized rotation of the arcuate slotted plates so that the interlaced straight fingers move closer together or farther apart with the fixed skeleton assembly curved fingers for different types of grain.