Abstract: A universal grinding bar adapted to be connected to a standardized, quick-change tool holder can be devised for use with conventional engine lathes, milling machines and the like and used as a standardized tool without the limitations of direct coupling to the drive of the engine lathe or milling machine. The universal grinding bar includes a modular delivery tube of selected shape and length and a modular turbine housing connected to the delivery tube and including a selected one of a plurality of pneumatic motors characterized by different operating speeds. Pressurized air is coupled through the end of the delivery tube distal from the turbine housing and is delivered to the pneumatic motor through a pressure tube. The spent air is then returned through a metering plate between the turbine housing delivery tube through an internal bore within the delivery tube to exhaust ports at the distal end. The delivery tube is of such diameter to allow connection to a conventional quick-change tool holder.