30 C.F.R. § 57.14115

Stationary grinding machines, other than special bit grinders, shall be equipped with—

(a) Peripheral hoods capable of withstanding the force of a bursting wheel and enclosing not less than 270°—of the periphery of the wheel;

(b) Adjustable tool rests set so that the distance between the grinding surface of the wheel and the tool rest is not greater than 1/8 inch; and

(c) A safety washer on each side of the wheel.