A through beam shear angle change, cutting blade deflection detector including a cutting member within a shear box of a recycling machine, a through beam sensor including an emitter disposed on the cutting member and a receiver disposed on the cutting member, the receiver being disposed relative to the emitter for receiving a signal emitted from the emitter, and a controller connected to at least the receiver, the controller being configured to determine an amount of cutting member deflection based on an output of the receiver.