Abstract: A tool block and holder for metal working lathes, comprising, a tool block having a tool channel extending therethrough sized to receive snugly a collet holder with a collar at its proximate end serving as a stop against the tool block, and first coolant channel that communicates a fluid coolant from a source external to the tool block to the tool channel at a point beyond the distal end of the collet holder; a collet sized to be received snugly within the collet holder and having a hollow interior and a nose at its proximate end with an opening sized to receive the shank of a metal working tool and having male threads at its distal end; and a draw nut having a proximate end sized to be received snugly within the tool channel, female threads at its proximate end sized to receive the male threads at the distal end of the collet, a flange at the distal end of the draw nut serving as a stop against the tool block, and second coolant channel in fluid communication with the first coolant channel and the hollow int