There has been considerable debate as to the optimal geometry for the focusing tube of a conventional abrasive waterjet nozzle. In order to carry out a simple, yet relatively inexpensive comparison, steel nozzles were manufactured with one of four cone angles into the throat, and a throat of four different lengths (for a total of 16 combinations). The nozzles were tested using steel abrasive as the cutting particle; since this allowed testing without unacceptable nozzle wear (garnet eroded a nozzle in seconds). The results also compared two different mixing chamber geometries. The first series of tests showed that the shorter the focusing tube length (over the range tested) the more effective the nozzles cut, while an optimal angle for the converging cone changed with mixing chamber geometry. Results of the second series of tests, in which shorter nozzles were tested at the optimal cutting angle are also included and compared with existing commercial designs. © BHR Group 2008 Water Jetting 19.