There is provided a method for drilling a cased hole and installing a micropile. The vacuum pump is distinguished by the fact that the rotor consists of plastic and is formed as one piece. The rim extends to a depth no greater than the thickness of the housing outer surface. There is also at least one point C on a plane Pi which is tangential to each surface element Si, such that all of the segments of a straight line D connecting every point R of the cooling surface S to point C are only located inside the mold. This is done for each OS instance where the job is run.