A mechanical part-stream sampler includes a housing positionable over a conveyor belt from which material is to be sampled. The housing encases one or more cutter arms and adjustable cutters. The cutter arms rotate 360 degrees such that the cutters extract a sample of material from the conveyor belt and deposit the sample in a discharge chute in the housing for later analysis. A programmable logic controller and human machine interface screen can be used to operate the sampler and to control the timing and speed of the cutter arms.