the tank 20 is being soldered to tubes 14 and 22 the heat sink also prevents the solder from going too far within tank 20 thereby avoiding any interference with the irrigation and aspiration flow channels within needle assembly 10 once the solder has solidified fixture 30 may be removed from needle assembly 10 the three piece construction of fixture 30 permits such removal the remaining operation necessary to complete the manufacture of needle assembly 10 consists of forming the tapered portion of outer tube 17 and to make the substantially leakproof joint at location 18 this is accomplished by use of a forming die 44 which has internally machined therein the final shape of the tapered portion of outer tube 17 needle assembly 10 is appropriately chucked in a machine capable of rotating needle assembly 10 while needle assembly 10 is being rotated the forming die 44 is gradually brought into contact with needle assembly 10 which gradually forms the tapered portion on outer tube 17 and the leakproof joint at location 18 when needle assembly 10 is attached to a housing of an appropriate ophthalmic instrument it is ready for use by a surgeon the coaxial tip is inserted in an eye through the sclera the cataract is drawn into the aspiration port 16 as a result of the aspiration flow through inner tube 14 during such aspiration irrigation flow in a direction reverse to that of the aspiration flow enters tube 22 flows through tank 20 and enters outer tube 17 once in outer tube 17 the irrigation flow and the aspiration flow are coaxial the irrigation flow simultaneously exits through.