Disc Blade Terminology & Usage
Disc blades, or disc harrow blades, are used to till soil before planting crops or at the end of the season to chop up the unwanted remainders. The main types of disc harrow blades are notched disc blades and plain disc blades, distinguished by the edge of the blade. Notched blades are best used to chop through old crops and hard soil while the smooth disc blades are great for soil that has been plowed and tilled previously and does not contain hard soil, limbs, branches, and other types of debris. Notched disc blades have a tendency to wear out quicker than smooth.
Disc blades vary in thickness, diameter, and concavity. The concavity, or depth of the curvature of the blade, assists in displacing and aerating the soil. You can measure the concavity by placing the blade on a flat surface with the cutting edges down, then measure through the center hold from the flat surface to the inside edge of the blade center. The diameter should be based on your harrow assembly or implement used to till and the thickness can help with the weight and durability of the blade. Diameters sold by Agri Supply range from 12 inches to 36 inches.
Disc harrow assemblies and plow implements are affixed with various numbers of disc blades and can be offset for first time plowing. The blades have center holes that fit square or round axles and range from 7/8" to 1-1/4" axle sizes. They are separated by spacers, spools, and other disc harrow parts on the disc axle.