Multi-piece anti-vibration locking fastener having coaxially arranged inner and outer opposite threaded bolts in combination with successive and opposite threaded profiles within a thickened base layer

A locking fastener assembly, comprising:

• a base layer having a smooth upper surface within which is configured a blind hole including a first wider diameter passageway exhibiting a first interiorly threaded orientation and a second succeeding and narrower diameter passageway exhibiting a second opposite threaded orientation extending a selected distance beyond a bottom end wall of said first wider passageway;
• a second thinner surface layer positioned over said base layer and having an inner rim defining aperture aligning with said blind hole;
• a first elongated fastener including a first head and a first stem exhibiting a first arrangement of exterior threads extending a length of said first stem and which is threadably inter-engageable with said first interiorly threaded orientation of said base layer, said first elongated fastener further including an interior passageway extending its axial length;
• said first head of said first elongated fastener further comprising a multi-sided polygonal configuration with an undercut recess profile including an annular side wall and interconnected bottom recessed wall arrayed in communication with said interior passageway;
• a second elongated and narrower diameter fastener having a second head and a second stem including a second arrangement of exterior threads extending along a length of said second stem and which are counter oriented to said first arrangement of exterior threads of said first fastener;
• said second head exhibiting a curved and enlarged diameter head having a bit receiving recess and a flattened underside surface which, upon installation within said first fastener and into said narrower diameter passageway of said base layer, causing said second head to seat within said undercut recess of said first head so that said flattened underside of said second screw head abuts said recessed wall of said first head and said curved and enlarged diameter does not project above said first head;
• and
• following said first elongated fastener being installed into said base layer and so that said first head is adapted to abut and secure said second layer against said base layer, said second fastener being installed through the interior passageway of said first fastener and so that said second arrangement of threads engage with said second succeeding and narrower diameter passageway of said base layer, loosening of either of said first and second fasteners being prevented by their counter-threaded orientation.