A backout or relief cut is a plow style dado milled on the back side of a wood moulding to help prevent cupping, warping, and relieve stress in milled lumber, it also allows for airflow between surfaces while providing a good transition between framing and sheetrock when installed. In general, one sixteenth to one eighth of an inch in height for each three quarter to one inch of thickness of milled wood is a common practice. We prefer to use 45-degree angles in the transition areas, reason being, it will be easier to sharpen the knife when needed, the cutters will also benefit from longer manufacturing milling times than that of backout/relief cut designs that have transitions of greater angles. We have over two hundred styles of backout and relief cuts for casings, baseboards, tongue & groove flooring, and door jambs.
If by chance you don't find a relief cut that works for your current application, just send us a sketch. We would be honored to design a new backout profile on cad, cut an acrylic template on our cnc machinery, and grind a set of cutters on our Weinig R 960 grinder, in any high quality knife steel we offer. Don't forget, we have an easy to use knife calculator located directly under every design in our catalog, offering immediate, accurate price quotes.