Re-usable, spin-stopping fastener

Claim 1

In a tightenable fastening assembly capable of being retightened, without auxiliary retention against rotation in an initially non-tapered bore formed in work structure that includes multiple panels and a flowable bond at the interface therebetween, the combination with said work structure comprising a. a fastener head and shank, the shank defining first, second and third sections in a lengthwise direction away from the head, b. the second section having a uniform diameter along its length which diameter is sufficiently larger than the bore diameter to provide slight piloting interference with the work when the fastener is inserted in the bore, said second section diameter exceedinG the bore diameter by an amount within the range 0.0006 to 0.0036 inch, the second section sized to remain in and protrude from the bore when the fastener head engages one side of the work, the second section having a nose tapering toward the third section which is of lesser diameter than the second section so as not to interfere with the bore diameter upon said insertion. c. the third section protruding from the work and being threaded to receive a nut so that the nut may engage the opposite side of the work and tighten thereagainst, the nut being recessed to receive the end of the second section also protruding from the work, the nut being re-tightenable to predetermined torque level as the tension in the shank decreases due to flowage of the bond, and d. the first section being tapered away from the head toward the second section and being sufficiently oversized in relation to the bore diameter that frictional interference force develops to prevent rotation of the fastener shank in the hole in response to said nut tightening acting to draw said head toward said one side of the work, the tapered length of the first section exceeding the length of the second section and said taper being about 0.250 inches per foot of section length, the maximum diameter of the first section along the tapered length thereof exceeding the initial bore diameter by about 0.0007 inch, the sum of the lengths of the first and second sections being within the range from about 1/8 inch to about 1/2 inch, and the overall length of the second and third sections being sufficient that the nut thread interfits the third section thread when the first section taper initially engages the work bore without compressively deforming same. 99