A machine tool housing having an arcuate cover. The housing defines a machining cavity. The machining cavity is defined in part by an arcuate cavity door, a partitioning wall having an arcuate front edge, a rear wall and an end wall. The arcuate cavity door may be moved between an open and closed position by a roller assembly. A blade assembly includes a blade which is in substantially consistent contact with the inside contoured surface of the cavity door to adequately clean the inside surface.