minimum plate thickness for tapped hole
minimum plate thickness for tapped hole
(OP)
I think I read this here before but I can't find it anymore.
What is the absolute minimum steel plate thickness I can use for a tapped hole to put a 1/2" dia. A307 bolt? I mean minimum from a fabrication stand point only.
I'm not looking to develop the bolt capacity. Very lightly loaded, if there is a load at all (100-200 lbs. tension).
What is the absolute minimum steel plate thickness I can use for a tapped hole to put a 1/2" dia. A307 bolt? I mean minimum from a fabrication stand point only.
I'm not looking to develop the bolt capacity. Very lightly loaded, if there is a load at all (100-200 lbs. tension).






RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
Usually the depth is at least one diameter of male screw.
For tapping into steel with less strength than the bolt I would say at least 1.5 tmes screw dia.
deserfox
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
I'd a thunk the answer would be in pitches, not diameters.
It also depends on how the thread is tapped - a hole that is tapped using a handheld wrench will have significantly greater widening than one that is machine tapped.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: minimum plate thickness for tapped hole
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
The minimums for this type of thing are based on loaded bolts and achieving something similar to what you'd get with a corresponding nut. As a rule of thumb, I suppose you could say that the plate thickness needs to equal the nut thickness for that bolt, if load capacity is an issue.
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
htt
notes as on the site below:-
Various studies on thread loading have established that the shear stress is not evenly distributed across the threads. The first thread withstanding the load is the highest stressed and the next one is much less stressed and so on... . If the thread materials were very hard and did not yield the first thread could be withstanding nearly all the load. However because of material yielding there is some distribution of the load. A study (see link 2 below) has established that for a typical grade 8 nut the percentage of the load taken by consecutive threads are about 34%, 23%, 16%,11%,9%, 7% .... This effect can be alleviated by using very accurate threads and by using ductile materials for the components. It has been established that,for carbon steel, there is no increase in thread shear strength by having a thread engagement length in excess of the screw diameter. It is normal practice to use a tapped hole depth of about 1,5 x nominal diameter - this allows at least 1 diameter of good thread engagement.
A very simple rule that can be applied for that vast majority of applications is that a thread length of 80% of the screw diameter (standard nut height) is sufficient for ensuring that the screw will fail in tension before the female thread (nut) fails in thread stripping (assuming the screw and nut are similar materials). Equations below indicate how to make adjustments if the tapped metal (nut) strength is lower than the screw/bolt.
desertfox
RE: minimum plate thickness for tapped hole
Follow up question: What would be more efficient to fabricate? A plate with a tapped hole or a plate with a nut welded to a regular hole?
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
whats on the far side ? free space ?? maybe an anchor nut ? (if you have pace for a nutsert, you've probably got space for an anchor nut.
RE: minimum plate thickness for tapped hole
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: minimum plate thickness for tapped hole
One place to find them is from the Mcmaster catalog.
I beleave the brand name is "hollo-bolt"
http://www.mcmaster.com/#specialty-bolts/=ccyy45
however there are many differnt manufactures and suppliers available.
These are allowed by the AISC for structural applications (13th ed pp. 7-13)including in slip critical and tension applications.
The minimum plate thickness may not be an issue because you would not be relying on a thread for anything.
RE: minimum plate thickness for tapped hole
3/16" to 1/4" are easy to be bent but if it gets to 3/8" thk., not a lot of fabricators can do it, I think.
If I go with inserts then I can simply use 1/4" bent plate. Then the question becomes which option is easier and cheaper to fabricate. A thin plate with threaded insert or a thicker plate with a tapped hole.
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
RE: minimum plate thickness for tapped hole
Ron - Great point. Thanks!