Rule 125. A guard for an abrasive wheel on a bench, floor, or cylindrical grinder shall be constructed so that the peripheral protecting member can be adjusted to the decreasing diameter of the abrasive wheel.The distance between the abrasive wheel and the end of the peripheral member at the top shall not exceed 1/4 inch. An adjustable tongue may be used to achieve this dimension.
Mich. Admin. Code R. 408.10125