mmgemini Posted January 9, 2006 Share Posted January 9, 2006 I wonder how many of you have used these 8.8 metric bolts??? I find that they're krap.Carrots are stronger.I'm not refering to the little 6/8 mm ones but the 10/12 mm ones.They snap when trying to remove them.. I much prefered the old "S"s and "T" grade UNF stuff. Another point. Why use HT bolts with a mild steel nut??? Or should that be a mild steel nut with HT bolts. LOL I eat rat poison mike I can cause trouble in an empty house !! Quote Link to comment Share on other sites More sharing options...
GBMUD Posted January 9, 2006 Share Posted January 9, 2006 Another point.Why use HT bolts with a mild steel nut??? Or should that be a mild steel nut with HT bolts. LOL Perhaps HT bolts are good in shear too. Only the bolt will be stressed, not the nut. Do you find the bolts are breaking? Perhaps you just don't know your own strength? Chris Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 9, 2006 Author Share Posted January 9, 2006 I was thinking of a nut fitted to the bolt for a towing hitch. I eat rat poison mike I can cause trouble in an empty house. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted January 9, 2006 Share Posted January 9, 2006 I'm not refering to the little 6/8 mm ones but the 10/12 mm ones.They snap when trying to remove them.I was thinking of a nut fitted to the bolt for a towing hitch. Perhaps you should be specifying bigger (M16?) bolts? Not being much help am I? Chris Quote Link to comment Share on other sites More sharing options...
gsr341 Posted January 9, 2006 Share Posted January 9, 2006 we have some large 30'x6' vibratory conveyers in work , which reguallry sheds m16 8.8s (around 120 bolts in machine) we allways tourqe them up correct , but they still fail , never ever caused by the m 16mild steel nyloc nuts failing we have even tryed using very expensive titanium bolts but they still failed Quote Link to comment Share on other sites More sharing options...
rtbarton Posted January 9, 2006 Share Posted January 9, 2006 I think you'll find the nuts are high tensile steel too. According to my supplier none of the larger manufacturers make mild steel nuts. The ones I sell have a small 8 stamped on them. If they're snapping when you remove them it will be because the nut has seized on to the bolt, otherwise the nut would turn first! Quote Link to comment Share on other sites More sharing options...
Mark90 Posted January 9, 2006 Share Posted January 9, 2006 Mike, you are turning them the right way when undoing them aren't you? Quote Link to comment Share on other sites More sharing options...
rtbarton Posted January 9, 2006 Share Posted January 9, 2006 Mike, you are turning them the right way when undoing them aren't you? I always fit a left hand nut onto a right handed bolt, that way if turning the nut doesn't undo it, turning the bolt will. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 9, 2006 Author Share Posted January 9, 2006 Wellafter all these years working in the motor industery I think I know which way to turn the thing.LOL I'm finding a lot of the 8.8 bolts do shear.Especially when used with captive or welded nuts. What suprises me is that I fing the just shear.No sort of warning where you can back off and retry after adding some lubricant. I eat rat poison mike I can cause trouble in am empty house !!! Quote Link to comment Share on other sites More sharing options...
bishbosh Posted January 9, 2006 Share Posted January 9, 2006 Simple fact: Nuts should be rated to the same grade or higher than the bolt they are to be used with. Also, at least one full turn of the threads of the bolt should project through the nut to mobilise the full nut strength. If bolts are breaking regularly then the connection is poorly designed or is being subjected to loads beyond its design parameters. In the case of the machine it may be fatigue in the bolts. Quote Link to comment Share on other sites More sharing options...
minivin Posted January 9, 2006 Share Posted January 9, 2006 Also, at least one full turn of the threads of the bolt should project through the nut to mobilise the full nut strength. 1.5 turns I was taught during my aviation apprenticeship Quote Link to comment Share on other sites More sharing options...
western Posted January 9, 2006 Share Posted January 9, 2006 1.5 turns I was taught during my aviation apprenticeship Yep and that's the minimum threads should protrude. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 10, 2006 Author Share Posted January 10, 2006 Simple fact:Nuts should be rated to the same grade or higher than the bolt they are to be used with. Also, at least one full turn of the threads of the bolt should project through the nut to mobilise the full nut strength. If bolts are breaking regularly then the connection is poorly designed or is being subjected to loads beyond its design parameters. In the case of the machine it may be fatigue in the bolts. So Land Rover aren't fitting the correct bolt is what your saying? I eat rat poison mike I can cause trouble in an empty house. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted January 10, 2006 Share Posted January 10, 2006 The amount of thread protruding is really only a guide - 1 turn or 1.5 turns or 5 turns is neither here nor there as long as all the threads of the nut are engaged on the bolt. It is just easy to say 1 turn or whatever to ensure all the threads are engaged. So Land Rover aren't fitting the correct bolt is what your saying? Where did I say that??? Quote Link to comment Share on other sites More sharing options...
Bush65 Posted January 10, 2006 Share Posted January 10, 2006 we have some large 30'x6' vibratory conveyers in work , which reguallry sheds m16 8.8s (around 120 bolts in machine) we allways tourqe them up correct , but they still fail , never ever caused by the m 16mild steel nyloc nuts failing we have even tryed using very expensive titanium bolts but they still failed With vibratory conveyors, screens etc. it is best to tighten the bolts to the yield point. The bolts designed for tightening to yield have larger heads and nuts than normal. When tightening to yield, use of a specified tightening torque is generally not acceptable (not accurate enough due to friction). The part turn method works much better. The bolts should not break or loosen if tightened to yield. If they do then there is something fundamentally wrong with the design. Huck Bolts are best for this type of equipment. Correct pre-load is ensured, they take less time to install and tension than normal bolts and will never loosen. Downsides of Huck Bolts are: 1. The cost of the tightening tool, (but these can be hired when required). The tool is hydraulic and stretches the bolt before crimping the nut onto the threads (actually a series of parallel grooves, not a helical thread). The part of the bolt that protrudes through the nut (that the tool grips) breaks off similar to a very large pop rivet. 2.They can not be undone - have to use cut the nut off to remove them. Although washers are not required with Huck Bolts, always use a flat washer on the side that will be cut if they have to be removed with a gas axe (this will save gouging into the machine). Quote Link to comment Share on other sites More sharing options...
mmgemini Posted January 10, 2006 Author Share Posted January 10, 2006 The amount of thread protruding is really only a guide - 1 turn or 1.5 turns or 5 turns is neither here nor there as long as all the threads of the nut are engaged on the bolt. It is just easy to say 1 turn or whatever to ensure all the threads are engaged.Where did I say that??? Well it's Land Rover OE that I keep breaking.LOL I eat rat poison mike I can cause trouble in an empty house !!! Quote Link to comment Share on other sites More sharing options...
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