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Posted by stryped on April 24, 2008, 11:42 am
Please log in for more thread options > On Thu, 24 Apr 2008 05:17:15 -0700 (PDT), stryped
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> >> On Wed, 23 Apr 2008 14:18:15 -0700 (PDT), stryped
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> >> >I have posted about building a trailer. Would like to weld and bolt
> >> >the A frame underneath the actual trailer. (For more peace of mind I
> >> >guess).
>
> >> >I think a grade 8 bolt has a tensile stregth of 150,000 psi. Would
> >> >puting a bolt throught the top of the tongue tube into the bottom of
> >> >the frame tube through threading or something give enought strength to=
> >> >hold the thing together in a worst case senario? (like a half inch
> >> >bolt)? Or would it be necessary to go through both tubes with a long
> >> >bolt. (This tubing is 3 inches and the thickness is 1/4 inch. Would
> >> >one bolt on each side cover it?
>
> >> >Trailer would probably have one 3500 lb axle. Probably be 10 feet
> >> >long.
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> >> >Since 150,000 psi is the bolt, does that mean it is stronger than a
> >> >weld with 7018 rod which is 70,0000 psi?
>
> >> >Just trying to learn.
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> >> You need to do a bit of googling. When you discuss metal strengths you
> >> almost always talk about tensile strength, i.e., the strength of the
> >> item being stretched. But when you actually use the item it is
> >> frequently used in a manner where the load is in shear. i.e., trying
> >> to slice the bolt in half.
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> >> Tensile strength and shear strength are not the same thing, however
> >> shear strength can be calculated approximately from tensile strength.
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> >> Another point that you might want to ponder is that a properly made
> >> weld is as strong, or stronger, then the parent metal -- so why the
> >> bolt?
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> >> Bruce-in-Bangkok
> >> (correct email address for reply)- Hide quoted text -
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> >> - Show quoted text -
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> >I guess as a "fail safe" if a weld was not good. Also, actually it
> >would help hold the unit in place and centered before welding.
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> >By the way, this 3 inch tubing I got is 3/16 I found out last night,
> >not 1/4.
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> I'm not trying to be a smart ass but really, if you don't feel
> confident enough in your welding to build a trailer, then don't build
> it. Practice a bit.
>
> Assuming that you are even marginally competent it shouldn't take more
> then a day or of practice to become able to make good 100% penetration
> welds in 3/16" or 1/4" mild steel.
>
> One of the secrets is to position as many of the parts as possible in
> such a manner that you have easy access to them and they are as near
> as possible to being flat welds. Position welding is harder to learn
> so try not to do any, or at least as little as possible.
>
> Bruce-in-Bangkok
> (correct email address for reply)- Hide quoted text -
>
> - Show quoted text -
I am going to be practicing before i ever build this thing, I am just
looking for ideas. I have welded several projects already, none of
them really have broken. Most were with Mig though and I was going to
use stick for the trailer. (My Mig is only 135 amps, 110v.)
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>the A frame underneath the actual trailer. (For more peace of mind I
>guess).
>
>I think a grade 8 bolt has a tensile stregth of 150,000 psi. Would
>puting a bolt throught the top of the tongue tube into the bottom of
>the frame tube through threading or something give enought strength to
>hold the thing together in a worst case senario? (like a half inch
>bolt)? Or would it be necessary to go through both tubes with a long
>bolt. (This tubing is 3 inches and the thickness is 1/4 inch. Would
>one bolt on each side cover it?
>
>Trailer would probably have one 3500 lb axle. Probably be 10 feet
>long.
>
>Since 150,000 psi is the bolt, does that mean it is stronger than a
>weld with 7018 rod which is 70,0000 psi?
>
>Just trying to learn.