Sealing fastener with multiple threads

1. A fastener for joining an object to another structure and comprising a head having a portion adapted for receiving torque to rotate said fastener, and an annular tapered portion joined to said torque receiving portion, and a shank joined to and extending from said annular tapered portion and terminating in a point adapted to extend through a preformed aperture in said object or create such an aperture as it is rotatably forced against said object,

said shank having a primary thread continuously extending along its periphery from at least a location removed from said head and ending at said annular tapered portion in a primary terminus along the circumference of said shank, said primary thread having a pitch and being spirally wound about said shank in convolutions spaced to create a continuous, unthreaded portion of said shank between said primary thread convolutions, and

a supplemental thread located in at least a part of said continuous unthreaded portion of said shank between said primary thread convolutions, said supplemental thread ending at said annular tapered portion in a supplemental terminus spaced from said primary terminus along the circumference of said shank.

2. A fastener as claimed in claim 1 , in which said primary and supplemental termini are spaced from each other by at least 90 degrees.

3. A fastener as claimed in claim 1 , in which said primary and supplemental termini are spaced from each other by about 180 degrees.

4. A fastener as claimed in claim 1 , in which said primary thread has a uniform pitch, and said supplemental thread has the same pitch.

5. A fastener as claimed in claim 4 , in which said supplemental thread is located equidistant from adjacent convolutions of said primary thread.

6. A fastener as claimed in claim 1 , said annular, tapered portion being substantially frusto-conical in shape with the lesser diameter frustum being located at said shank and being of substantially the same diameter as said shank.

7. The combination of a fastener for joining an object to another structure and comprising a head and a shank joined to and extending from said head and terminating in a point adapted to extend through a preformed aperture in said object or create such an aperture as it is rotatably forced against said object,

said shank having a primary thread continuously extending along its periphery from at least a location removed from said head and ending at said head in a primary terminus along the circumference of said shank, said primary thread having a pitch and being spirally wound about said shank in convolutions spaced to create a continuous, unthreaded portion of said shank between said primary thread convolutions, and

a supplemental thread located in said continuous unthreaded portion of said shank between said primary thread convolutions, said supplemental thread ending at said head in a supplemental terminus spaced from said primary terminus along the circumference of said shank,

and a washer having an aperture therethrough and positioned with said fastener shank extending through said aperture, said washer being located at said termini of said primary and supplemental threads and being supported against axial movement in the direction of said shank point by said termini.

8. The combination claimed in claim 7 , in which said head comprises a portion adapted for receiving torque to rotate said screw, and a tapered portion joined to said torque receiving portion and to said shank, said primary and supplemental termini ending at said tapered portion of said head.

9. The combination claimed in claim 8 , said tapered portion being substantially frusto-conical in shape with the lesser diameter frustum being located at said shank and being of substantially the same diameter as said shank, said washer surrounding said tapered portion of said head.

10. The combination claimed in claim 7 , in which said primary and secondary termini are spaced from each other along the circumference of said shank by more than 90 degrees.

11. The combination claimed in claim 10 , in which said primary and second termini are spaced from each other along the circumference of said shank by about 180 degrees.

12. The combination of a fastener for joining an object to another structure and comprising a head, and a shank joined to and extending from said head and terminating in a point adapted to extend through a preformed aperture in said object or create such an aperture as it is rotatably forced against said object,

said shank having a primary thread continuously extending along its periphery from at least a location removed from said head and ending at said head in a primal terminus along the circumference of said shank, said primary thread having a pitch and being spirally wound about said shank in convolutions spaced to create a continuous, unthreaded portion of said shank between said primary thread convolutions, and

a supplemental thread located in said continuous unthreaded portion of said shank between said primary thread convolutions, said supplemental thread ending at said head at a supplemental terminus spaced from said primary terminus along the circumference of said shank,

said head having a portion thereof to receive torque applied to rotate said screw, said torque receiving portion being joined in the direction of said shank to an outwardly extending flange to which is attached an annular, tapered portion that is substantially frusto-conical in shape with the lesser diameter frustum being located at said shank and being of substantially the same diameter as said shank,

and a resilient washer having an aperture therethrough and positioned with said fastener extending through said aperture, said washer be located about said tapered portion of said head and being supported against axial movement along said shaft between said outwardly extending flange of said head and said termini of said primary and secondary threads.