Abstract: A portable round tube cutter has a hollow central shaft through which passes a length of tubing to be cut. A transmission gear jacket is axially slidable along the shaft and rotates with the shaft. A tool chuck has a tubing cutter that is manually movable into the tubing to cut the tubing at a desired location. The tool is fed into and away from the tubing by a manually operable gear engaging the transmission gear jacket to cause axial movement of the jacket along the central shaft. Such axial movement rotates a transmission gear which, in turn, is engaged with a rack on the cutting tool mount to move the cutting tool either towards or away from the tubing. A clamping device is also included to clamp the length of tubing in the desired cutting position.