Portable grinder

Claim 1

In combination with a portable grinder having: a shaft housing; a shaft rotatably mounted in the shaft housing with one end protruding therefrom; an annular abrasive element mounted on the protruding end having a periphery and an abrasive face; a motor operatively connected to the disc shaft for rotating the shaft and element to grind a surface with the abrasive face and thereby generate dust particles; an improvement of a vacuum hood assembly, comprising: an adapter sleeve mounted to the shaft housing coaxially surrounding the shaft; a dust hood mounted on the sleeve substantially enclosing the abrasive element except for the face; said dust hood having a periphery with a substantially circular air pervious shield composed of stiff bristles encircling and radially spaced from the periphery of the disc for engaging the surface to permit air to flow into the hood through the bristles about the periphery of the abrasive element and confine the dust particles within the hood; said dust hood being slidably mounted on the sleeve for axial movement relative to the shaft between an extended position in which the bristles extend forward of the abrasive face and a retracted position in which the bristles terminate substantially flush with the disc face; spring means mounted on the sleeve resiliently biasing the dust hood toward the extended position for (1) biasing the bristles into contact with the surface before the abrasive face as the grinder is applied to the surface, (2) maintaining a positive pressure of the bristles against the surface during engagement by the abrasive face, and (3) maintaining the bristles in contact with the surface while the abrasive face is being initially withdrawn from the surface; and an air duct formed in said hood and being adapted to operatively connect an air vacuum source to create a vacuum in the hood and draw air through the bristles, into the hood and out through the air duct to carry dust particles therewith.