Patent ID: 8602696

Claim:
A form tap for tapping an article, the form tap comprising: a longitudinal shank having a mounting end opposite a tip, the shank having a shank length; a thread portion comprising a plurality of threads for engaging a surface of the article, the thread portion extending longitudinally along the shank from the tip to a thread end, the thread portion comprising a finishing section and a chamfer portion extending between the tip and a transition thread, the thread portion comprising; a first region extending from the tip to the transition thread, a second region extending from the transition thread to a second region end intermediate the transition thread and the thread end, and a third region extending from the second region end to the thread end; a plurality of lobes extending through the first and second regions from the tip to the second region end, the lobes being spaced circumferentially around the shank and lying on a crest circumference, each lobe being disposed between respective first and second convex relief portions, each relief portion being spaced radially inward from the crest circumference, each lobe having a lobe width, the lobe width at the second region end being greater than the lobe width at the tip; and a plurality of longitudinal lubrication grooves, each lubrication groove being disposed in a respective one of the relief portions and extending from the tip, through the entire first and second regions and extending through at least a portion of the third region; the third region comprising a plurality of finishing threads and being free of lobes.