Stick fit fastener recess system

A system, comprising:

• a female driver including a recess;
• and
• a threaded fastener, comprising:
• a male configured fastener having a threaded shaft defining a central longitudinal axis, a fastener head, and a male portion defining a projection extending axially outward from the fastener head, the projection including a central portion and a plurality of lobes radiating outwardly from the central portion, the projection adapted to be received in the recess of the female driver to drive the threaded fastener, wherein:
• each of the lobes has an installation driving surface and a removal driving surface, the installation and removal driving surfaces being constructed in substantially parallel alignment with the axis;
• the installation driving surface and removal driving surface of adjacent lobes are separated by a respective transition contour, the transition contour forming a radially inward-most portion of the lobes, the inward most portion abutting the central portion;
• a wedge is formed in the transition contour to present a tapered interface surface, the tapered interface surface having a top, a bottom and a pair of opposed edges, a width of the tapered interface surface tapering from wider at the top of the tapered interface surface proximate a top of the projection to narrower at the bottom of the tapered interface surface proximate a bottom of the projection;
• and
• the tapered interface surface positioned a root radial distance from the axis at the bottom of the tapered interface surface, the root radial distance defining an inner radius, the tapered interface surface positioned a top radial distance from the axis at the top of the tapered interface surface, the top radial distance being larger than the root radial distance,
• wherein the tapered interface surface and the recess are constructed to form a frictional engagement with each other at two interface regions on the tapered interface surface that are separate from each other.

A system, comprising:

• a female driver including a recess;
• and
• a threaded fastener, comprising:
• a male configured fastener having a head, a threaded shaft defining a central longitudinal axis, and a male portion defining a projection extending axially outward from the head, the projection including a central portion and a plurality of lobes radiating outwardly from the central portion, wherein:
• each of the lobes has an installation driving surface and a removal driving surface, the installation and removal driving surfaces being constructed in substantially parallel alignment with the axis;
• the installation driving surface and removal driving surface of adjacent lobes are separated by a respective transition contour, the transition contour forming a radially inward-most portion of the lobes, the inward most portion abutting the central portion;
• a wedge is formed in the transition contour to present a tapered interface surface, the tapered interface surface having a top, a bottom and a pair of opposed edges, a width of the tapered interface surface tapering from wider at the top of the tapered interface surface proximate a top of the projection to narrower at the bottom of the tapered interface surface proximate a bottom of the projection;
• and
• the tapered interface surface is positioned a root radial distance from the axis at the bottom of the tapered interface surface, the root radial distance defining an inner radius, the tapered interface surface positioned a top radial distance from the axis at the top of the tapered interface surface, the top radial distance being larger than the root radial distance,
• wherein the threaded fastener and the recess are configured such that the recess can receive the projection of the male configured fastener in the recess in mating engagement along a lobe engagement length with one of the installation and removal driving surfaces of the lobes of the projection such that a ratio of the lobe engagement length to a diameter of the projection is greater than 0.11.

A threaded fastener, comprising:

• a male configured fastener having a head, a threaded shaft defining a central longitudinal axis, and a male portion defining a projection extending axially outward from the head, the projection including a central portion and a plurality of lobes radiating outwardly from the central portion, wherein:
• each of the lobes has an installation driving surface and a removal driving surface, the installation and removal driving surfaces being constructed in substantially parallel alignment with the axis;
• the installation driving surface and removal driving surface of adjacent lobes are separated by a respective transition contour, the transition contour forming a radially inward-most portion of the lobes, the inward most portion abutting the central portion;
• a wedge is formed in the transition contour to present a tapered interface surface, the tapered interface surface having a top, a bottom and a pair of opposed edges, a width of the tapered interface surface tapering from wider at the top of the tapered interface surface proximate a top of the projection to narrower at the bottom of the tapered interface surface proximate a bottom of the projection;
• and
• the tapered interface surface is positioned a root radial distance from the axis at the bottom of the tapered interface surface, the root radial distance defining an inner radius, the tapered interface surface positioned a top radial distance from the axis at the top of the tapered interface surface, the top radial distance being larger than the root radial distance,
• wherein at least one of the installation driving surfaces and removal driving surfaces is configured to define a spiral that has an initial point spaced from the central longitudinal axis by an initial radius and extends to an outer terminal point at a radius that is no more than about 3.5 times that of the initial radius.

A system, comprising:

• a female driver including a recess;
• and
• a threaded fastener, comprising:
• a male configured fastener having a head configured to be received in the recess to drive the threaded fastener by the female driver, a threaded shaft defining a central longitudinal axis, and a male portion defining a projection extending axially outward from the head, the projection including a central portion and a plurality of lobes radiating outwardly from the central portion, wherein:
• each of the lobes has an installation driving surface and a removal driving surface, the installation and removal driving surfaces being constructed in substantially parallel alignment with the axis;
• the installation driving surface and removal driving surface of adjacent lobes are separated by a respective transition contour, the transition contour forming a radially inward-most portion of the lobes, the inward most portion abutting the central portion;
• a wedge is formed in the transition contour to present a tapered interface surface, the tapered interface surface having a top, a bottom and a pair of opposed edges, a width of the tapered interface surface tapering from wider at the top of the tapered interface surface proximate a top of the projection to narrower at the bottom of the tapered interface surface proximate a bottom of the projection;
• and
• the tapered interface surface is positioned a root radial distance from the axis at the bottom of the tapered interface surface, the root radial distance defining an inner radius, the tapered interface surface positioned a top radial distance from the axis at the top of the tapered interface surface, the top radial distance being larger than the root radial distance,
• wherein at least one of the installation driving surfaces and removal driving surfaces is configured to define a spiral that has an initial point spaced from the central longitudinal axis by an initial radius and extends to an outer terminal point at a radius that is no more than about 3.5 times that of the initial radius.