Abstract: A separable carrier block assembly constructed for cooperation with a threaded lead screw of a machine. The carrier block assembly is constructed of mating block body halves comprising a first body half and a second body half. The mating body halves are separable at generally midway the depth of the carrier block body. The inside faces of the first and second block halves have cooperating and mating lands and grooves which are constructed and arranged to form a unitary nested carrier block body. A generally threaded semi-circular bore is formed into the inside faces of the first and second block body halves and extends generally midway of the depth of the nested carrier block body and extend along the length of the block body. The threaded bore matches the threads of a threaded lead screw. The threads of the threaded bore are preferably beveled. A second bore extends through the depth or thickness of the carrier block body and is located normal to and spaced from the threaded bore.