Abstract: A portable circular saw includes a single, one-piece thermoplastic housing having an interface portion which interchangeably mounts either a pivot adjust or vertical adjust subassembly, whereby two types of saws may be constructed using the same field case. One type adjusts saw blade depth of cut by pivotal movement of the housing relative to a reference plane. The other type adjusts saw blade depth of cut by transverse movement of the housing relative to the reference plane. The pivot adjust subassembly includes a one-piece foamed plastic auxiliary handle having an integral handgrip portion, pivot and lower guard bumper. The vertical adjust subassembly includes a one-piece rectangular rail member having an outer perimeter edge surface which guides the movement of a vertical adjust bracket. The pivot handle and the one-piece rail member, respectively, are interchangeably and snugly mounted on a common locating surface formed in the field case interface portion.