Patent ID: 8829389

Claim:
An improved method of manufacturing a helical bar concave, the method comprising: laser cutting flat metal sheet to form a grate having a helical pattern, the helical pattern includes a plurality of helical mounting framework and elongate helical cutouts extending substantially the length of the inside radius in the grate; the elongate helical cutouts in part forming a percent open area in the concave, the cutouts arranged in a helical geometry to form a substantially circumferential helical functional surface; cutting mounting holes in the mounting framework of the grate; rolling the flat, cut, metal grate to a predetermined radius; connecting the cut, rolled metal grate to a box-shaped frame; connecting rub bars to the interior functional surface of the grate for threshing a crop, the rub bars being mounted in a helical fashion meaning that the rub bars are mounted such that a length of each of the rub bars is substantially perpendicular to the helical cutouts and helical mounting framework.