Bolts - Full vs Partial Thread
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Gary_in_Indiana
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I would think that in a situation wherein closer tolerances were crucial it might matter. Also, if the spec's call for a the solid portion of a grade 5 bolt through two pieces and you use a threaded bolt that the threaded bolt would not offer 100% of the strength
For example, if you have two pieces which need to be in exact alignment and partially threaded bolts are OEM with the non-threaded portion through the two pieces with the threads beginning outside of them you would have a solid piece aligning the two holes. If you were to replace those with fully threaded bolts then only the very edges of the threads would be making contact. I would think that would offer less strength and resisitance to lateral stress than a solid piece.
That having been said, I have no firm knowledge or experience on which to base this. It just seems to make sense to me.
For example, if you have two pieces which need to be in exact alignment and partially threaded bolts are OEM with the non-threaded portion through the two pieces with the threads beginning outside of them you would have a solid piece aligning the two holes. If you were to replace those with fully threaded bolts then only the very edges of the threads would be making contact. I would think that would offer less strength and resisitance to lateral stress than a solid piece.
That having been said, I have no firm knowledge or experience on which to base this. It just seems to make sense to me.
Currmudgeon
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Just working off the top of my head, if the bolt is primarily loaded in tension, it doesn't matter. The thread root diameter is the skinniest part of the bolt, so it will tend to fail there. If the bolt is loaded in shear, it may be worthwhile to have full diameter steel taking the shear.
Gary_in_Indiana
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Yeah... That's what I meant. /forums/images/graemlins/grin.gif
slowzuki
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Fully threaded bolts are always weaker than partly threaded. The more roots you have that are loaded the weaker the bolt will be, kind of a weakest link or worst tolerance kinda thing.
Also there is the stress concentration at the base of the head when the mating surfaces aren't parallel. Not as bad for a partly threaded.
If it is designed for a partly use it /forums/images/graemlins/cool.gif
Also there is the stress concentration at the base of the head when the mating surfaces aren't parallel. Not as bad for a partly threaded.
If it is designed for a partly use it /forums/images/graemlins/cool.gif
yooperdave
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Threads included in the shear plane are type N.
Threads excluded in the shear plane are type X.
Type N are more common than type X, but type X have a higher capacity than type N.
If you are concerned about capacity, use grade 8 bolts instead of grade 2 or 5.
Yooper Dave
Threads excluded in the shear plane are type X.
Type N are more common than type X, but type X have a higher capacity than type N.
If you are concerned about capacity, use grade 8 bolts instead of grade 2 or 5.
Yooper Dave
