Abstract: A mobile machine for abrading a surface by propelling abrasive material against the surface from a blast assembly which moves from side to side of the machine. The machine includes a wheeled frame with a pair of parallel track members mounted across the frame. The blast assembly is supported on rollers which travel upon the track members. A coupling with a worm drive bore is mounted to the front and the rear of the blast assembly. A motor-drive worm drive shaft is journaled through each worm drive bore to move the blast assembly back and forth across the frame. The blast assembly includes a blast housing with a blast corridor and a blast opening to the surface being abraded, a hopper to gravity feed abrasive material into the blast corridor, a centrifugal blast wheel with rotating blades which propel abrasive material against the surface, a return corridor and an air wash. A remote dust collector is connected to the air wash to draw air and abrasive material from the blast opening to the air wash.