The invention relates to a powered saw (2) of the chop saw or mitre saw form. A circular blade is mounted to be rotated and is pivotally movable between raised and lowered position via movement of a support arm (26) with respect to the base (4). The support arm (26) is mounted on a slide (12) which is received within a bearing assembly (10). Means (52, 54) are provided to prevent debris and other material from entering the bearing assembly (10) thereby ensuring accurate and smooth movement between the slide (12) and the bearing assembly (10).