I'm making a small bone screw that specifies a custom buttress type thread form. I'm using a Citizen M20 machine. The major diameter of the screw at the threads is 1.4mm (.055"), and the threads run for about 11mm (.45"). I have tried single point threading without much success. I've tried threading in a single pass as well as breaking up the threading into three sections and blending the threading process. I've also supported the threading process from below with a custom support device attached to a position on the turrett.

I'm wondering if anyone has experience threading a long small diameter screw? I'm looking into thread whirling as well as thread forming with a Fette Head. Any tips or tricks would be appreciated.