Method and Apparatus for fabricating a spacer frame for use in an insulating glass unit. A roll former bends a strip of material to form a spacer frame having side walls to which an adhesive is applied during fabrication of an insulated glass unit. Alternately a plastic frame is formed by extrusion. A notching apparatus forms notches at locations that extend into the side walls to weaken the side walls for bending of said elongated channel into a closed structure. A downstream workstation predisposes specified locations of the sidewalls to facilitate bending of the spacer frame. The workstation forces the specified locations of the sidewalls inwardly toward each other at the predetermined bend locations.