Precision portable flange grinder

A method for grinding a flange on a duct, the flange having a periphery, an axis, and a radius, the method comprising:

• mounting a grinder assembly within a duct, the duct having a flange formed thereon, the grinder assembly including a grinding wheel that is arranged to rotate outside of the duct;
• rotating the grinding wheel;
• radially translating the grinder assembly along a radius of the flange to bring the grinding wheel in grinding contact with the flange;
• laterally translating the grinder assembly along an axis of the flange to bring the grinding wheel into grinding contact with the flange;
• and
• rotating the grinding assembly about a periphery of the flange.

A portable precision flange grinder for grinding a flange on a duct, the flange having an axis, a radius, an opening, and a periphery, the grinder comprising:

• a mount arranged for mounting the grinder within the duct, the mount being removably attachable to openings at ends of the duct including:
• a base plug for aligning the axis of the mount with an axis of the flange when a biasing force is applied;
• a base plate for securing the mount within the duct;
• and
• a plurality of base fasteners connecting the base plate to the base plug such that the fasteners apply the biasing force between the base plug and the base plate;
• a grinding wheel for grinding a flange on a duct, the grinding wheel being arranged to rotate along a periphery of the flange;
• a first linkage for laterally translating the grinding wheel along an axis of the flange to bring the grinding wheel laterally in grinding contact with the flange, the first linkage being laterally engageable with the mount along an axis of the flange;
• a second linkage for radially translating the grinding wheel along a radius of the flange to bring the grinding wheel radially in grinding contact with the flange, the second linkage being fixedly attachable to the first linkage and adjustably supporting the grinding wheel along the radius of the flange;
• and
• a bearing assembly for rotating the grinding wheel about the periphery of the flange, the bearing assembly being rotatably attachable to the first linkage and fixedly supporting the grinding wheel about the periphery of the flange.