Abstract: A tool includes a coupling, an inner adjustment sleeve, and an outer adjustment sleeve. The coupling connects a rotary tool to the inner adjustment sleeve. An adjustable portion of the inner adjustment sleeve is threadedly received in the outer adjustment sleeve. An offset aperture in the free end of the outer adjustment sleeve receives a tip of a valve stem for grinding. An optional cup at the end of the outer adjustment sleeve stabilizes the tool. A grinding bit with a shaft retained in a collet of the rotary tool is contained internally, in a channel, extending through the tool.