by use of about 235 parts per million of tetraisopropyl titanate catalyst the polymers were melted separately and the melts were led separately to the holes of a spinneret of the type shown in fig3 of cancio u s pat no 3 320 633 the two polymers were fed to the spinneret holes in a ratio by weight of 45 polyamide and 55 polyester the composite filaments had an oblong cross section of the type disclosed and claimed in fig2 of stanley u s pat no 4 118 534 the cross sections being characterized by a length width ratio of about 3 0 the molten filaments leaving the spinneret were attenuated by winding them up at about 500 yards per minute after being quenched with cross flow air at ambient temperature the final undrawn yarn consisted of 34 filaments at 25 denier each the polyamide component being 11 3 denier and the polyester component 13 8 denier the filaments were spun continuously for 3 days and the cross sectional dimensions of the filaments produced after 3 days were indistinguishable from the fiber produced during the first hour the spinneret was examined after spinning and no deposits had formed on the walls of the spinneret apertures examination of the wound filaments showed only very minor pre splitting had occurred in a comparative run the fibers were produced from a similar polyamide and a similar polyester only this time the polyester was produced with an antimony trioxide catalyst about 300 parts.