Patent ID: 7001450

Claim:
A method for constructing an air filter element having a center board and filter media; the method comprising: (a) providing a center board; the center board having first and second, opposite ends; and a system to hold filter media to the center board and prevent slippage between the center board and the filter media; (i) the system including a region located at least partially between the first and second ends; (A) the region including a bearing surface to hold and secure the filter media; (B) the bearing surface including a first thickness and a second thickness different from the first thickness; (b) providing filter media including a plurality of flutes; each of the flutes having a first end portion and a second end portion; selected ones of the flutes being open at the first end portion and closed at the second end portion; and selected ones of said flutes being closed at the first end portion and open at the second end portion; (c) securing the filter media to the center board including on the bearing surface; and (d) winding the filter media around the center board; (i) the bearing surface helping to hold and secure the filter media to the centerboard during winding; (ii) the filter media being wound around the center board to result in an element having opposite rounded ends joined by a pair of sides.