zim Posted December 15, 2010 Share Posted December 15, 2010 Evening, We've been chatting at work about how far in a stud must go into something before it makes no difference ? So was just wondering if there was a general rule of thumb to work it out ? i.e. an normal M10 bolt will be no better off going into a 20mm nut compared to a 50mm nut etc, but what is the minimum depth it should go in ? i'm assuming it's related to bolt diameter and pitch ? Cheers Gordon Quote Link to comment Share on other sites More sharing options...
Jeff Young Posted December 15, 2010 Share Posted December 15, 2010 The rule of thumb I seem to remember is 1.5 x diameter. So an M10 should engage 15mm (or 10 threads). That's for bolts in tension (such as studs). It'd be much less for bolts in shear (such as a shock or shackle bolt). Jeff. Quote Link to comment Share on other sites More sharing options...
Superpants Posted December 16, 2010 Share Posted December 16, 2010 There are a number of rules of thumb depending on the application; As has already been mentioned a min of 1.5 times OD is a good rule of thumb for bolts into tapped holes- but bear in mind the material the hole is tapped into will have an effect. I.e. the softer the material, the longer the thread engagement required. Also the failure mode (if the bolt is in tension)will change dependent on the length of engagement. For short engagements in soft material, the tapped thread will strip, for longer engagements in a higher strength material the bolt will fail. There are calculations to determine this. If you threading into a nut then it is normal practice to leave at a minimum of 1 to 2 threads protruding- primarily to ensure that the nut is on a fully formed section of the bolt, not on a taper. There is a lot of useful info on this site; Boltscience Quote Link to comment Share on other sites More sharing options...
bishbosh Posted December 17, 2010 Share Posted December 17, 2010 As mentioned, the key here is the material you are screwing in to. Most bolts are made of a much stronger material than the steel plates you will typically use, so if it is a critcal connection then either drill through and use a nut of the corresponding grade to the bolt or do the sums for the material you plan to tap. A rule of thumb could leave you well short of thread engagement. Quote Link to comment Share on other sites More sharing options...
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