The part is turned from 17-4 PH stainless steel and the ports and tapered bore are EDM machined in this nozzle. Both the bore and the ports have a complex contour that could only be machined using sinker EDM.

Another part of the nozzle assembly.

The port electrode:The electrode material is Telco copper. the burn time was about an hour per electrode and 6 electrodes were needed to burn all the ports to final finish and geometry