Nut with flexible gripping fingers and apparatus

A nut for rectilinear movement along lead screw, the nut comprising:

• a base;
• at least one flexible finger formed of a first material, the flexible finger joined to the base and extending axially from the base between a fixed end joined to the base and a free end;
• an adjustment mechanism engageable with the at least one flexible finger for radially flexing the at least one flexible finger;
• and
• a threaded portion fixed to the at least one flexible finger proximate the free end, the threaded portion being formed of a second material different than the first material;
• wherein the second material is a low friction material selected from the group consisting of:
• polytetrafluoroethylene, perfluoroalkoxy and fluorinated ethylene propylene;
• wherein the at least one flexible finger includes a plurality of flexible fingers, wherein an axially extending gap separates adjacent flexible fingers, the internally threaded portion extends axially only a portion of the length of the flexible fingers, wherein the threaded portion is formed by a plurality of pieces, wherein the axially extending gap separates adjacent ones of the pieces of the threaded portion;
• wherein the base, flexible fingers and threaded portion define a generally cylindrical channel and the only internal threads surrounding the cylindrical channel are formed by the internally threaded portion;
• and
• wherein the second material is molded to the first material.