Hand held portable band saw

A band saw which comprises:

• a generally U-shaped housing having confronting spaced end portions,
• means for carrying an associated closed loop shaped saw blade, said carrying means being on said housing and supporting the blade with a blade portion extending between said housing end portions and with the blade supported for travel in a closed loop path, said means for carrying including a plurality of rollers, each roller being mounted on a respective shaft,
• means for driving the blade on said means for carrying,
• means for adjusting blade tension by varying the angular orientation of the axis of at least one of said rollers relative to a plane extending through the axial extent of the band saw blade, said means for varying comprising a rotatably mounted cylinder and a cylindrical recess in the cylinder, said recess being disposed in generally eccentric relationship to said cylinder, and
• said means for adjusting includes bearing means at axially spaced points on said shaft mounting said one roller, each bearing means comprising a ball bearing and an annular member disposed between said rotatably mounted member and an outer race of the ball bearing, the outer race and rotatably mounted member having mutually engaging arcuate surfaces to effect self-alignment of the bearing and accommodate variation in orientation of said axis of said one roller.