Drive mandrel for helical thread inserts

An improved drive mandrel for the insertion of helical inserts having drive tangs into tapped bores which are undersized as respects the diameter of said inserts comprising, in combination, an axially elongated, generally cylindrical resilient polymeric body portion including torquing means at one end and a drive insert receiver portion at the other end, said body portion having an external peripheral thread portion for supporting said inserts, said thread portion beginning at said drive end and extending at least part way toward said torque applying end, said thread portion including crests and lands disposed between said crests, the improvement which comprises a substantially radially incompressible metallic drive blade extending axially within said body portion, said blade including a drive tooth projecting axially beyond said drive end of said body portion for engagement with the drive tang of an insert mounted on said threaded portion, said blade including diametrically opposed, axially extending side edges, said side edges being disposed substantially at the level of the said lands for at least the first convolution of said thread portion at said other end whereby radial inward constriction of said first convolution of said insert member is limited by said substantially radially incompressible drive blade.