Abstract: A chuck provided with a collapsible collet for holding one of a number of twist drills of different diameters is equipped with a holder for the collet, the holder being one for mounting in an appropriate power tool such as a drill press or lathe. There is a stationary sleeve within which rotate the holder, collet and drill. For lubricating and cooling the cutting operation where the drill engages the work, use is made of a pipe fitting in a boss on the stationary sleeve. A fluid line to the pipe fitting continuously supplies a cooling lubricant which flows from there through a succession of passageways in the sleeve and the holder so that the lubricant is ultimately discharged into axially extending slits of the collapsible collet. Emerging from the slits the lubricant flows over the surface of the drill until it reaches the cutting edge, the flow being in sufficient volume to wash away chips.