Abstract: A saw mill head saw having a thin-kerf circular saw blade whose diameter is in the range of 34 inches to 60 inches mounted in fixed position on a power driven mandrel for rotation therewith. The mandrel is journalled on bearings that can be adjustably positioned selectively to vary the angle of mandrel relative to the direction of travel of a log that moves while being cut. The saw blade is guided by a rigid robust saw guide unit located at the in-feed side of the saw and at a position below a saw cut made during operation of the head saw. The saw guide has a channel or gap portion receiving therein a selected portion of the saw blade and it is provided with a first group of discrete spaced apart blade contact pads and a second similar group with such groups being disposed on respective opposite sides of said saw blade.