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a while back there was a thread on AN bolts and nuts. [ i"ve tried to find the actual post but can"t] i think some one had said the nuts are rolled [ meaning internally] if i didn"t post it i thought at the time , that can"t be at all possible. well a while back the sutton rep came through
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Hi TonyYou are right again. In automotive they have been using tri-lobular bolts that roll the thread in the mating hole, for a few years now. The main advantage is that they eliminate the need to mask holes to prevent weld splatter and paint from getting in the holes. No chance of cross threading either, bloody hard to rework a car body on an assembly line when you only have 76 seconds per operation! They are proven to give the best possible bolted joint THE FIRST TIME USED. Then it rapidly turns to s@#^! If you try to use the same type of bolt again and you don"t start it perfectly in the previously formed thread then you very quickly end up with a very rough oversize hole. In summary they are bloody good for high volume assembly lines with high powered electronicly controlled torque guns, but I wouldn"t think of using them in my shed!!
TimC
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tim, i do remember seeing those types of bolts and nuts many years ago on car stuff, i just don"t do much car work thats all. i think [ i"m sure ] these taps are for " rolling " threads that form a threaded hole for "an" bolts to be used and reused. quite smart really.
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