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Thread: Weld pulled the other way?

  1. #1
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    Weld pulled the other way?

    Hey all,

    I was welding an outside corner today. Some 3/8" to 1/2 flat bar, only about 3" long each. Im fabricating a bracket for a disc brake caliper. I had it all in place, tacked up on the inside, then removed and welded the outside corner. The two plates only overlap by maybe 1/16" so lots of "corner" I also do one fillet pass on the inside to add a bit more strength. But that gets done last.

    Anyway, before doing the root run, I had set 2 bevels (one as a back up incase I bump the main one) to record the angle it was tacked at. What I found is that after each pass on the outside corner, the two pieces were pulling towards each other (to the internal corner)

    Why? I would have thought they pull apart, towards the weld...
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    Re: Weld pulled the other way?

    Was it supported properly? It looks like its sagged under its own weight.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Munkul View Post
    Was it supported properly? It looks like its sagged under its own weight.
    that there is exactly what I think happened.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Munkul View Post
    Was it supported properly? It looks like its sagged under its own weight.
    The two pics just show the set up to get correct location and angle. The angle is probably about 80 degrees. The way it was on the bench when welded, if it had "sagged" under its own weight, would have had the two parts move away from each other (get shallower angle), instead they closed up getting closer back to 90 degrees.

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    Re: Weld pulled the other way?

    Quote Originally Posted by ttoks View Post
    that there is exactly what I think happened.

    see above

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    Re: Weld pulled the other way?

    Only thing I can guess is that the tacks (on inside corner) weren't big enough, so that when you then went and put in a big hot root on the outside corner, it softened or melted your tacks, allowing the shrinking big root weld to pull the upper piece downward (thus increasing your overlap from 1/16" to something greater than that) and moving your angle from 80 to something closer to 90 ... I suspect that's what Munkul and Ttoks are saying in fewer words...

    Does the upper bolt hole still line up? If my theory is correct, even if you beat the thing back into the right angle, the bolt hole in your piece might be a bit too low to line up with the hole in the casting...
    Last edited by Kelvin; 4 Weeks Ago at 06:50 AM.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Kelvin View Post
    Only thing I can guess is that the tacks (on inside corner) weren't big enough, so that when you then went and put in a big hot root on the outside corner, it softened or melted your tacks, allowing the shrinking big root weld to pull the upper piece downward (thus increasing your overlap from 1/16" to something greater than that) and moving your angle from 80 to something closer to 90 ... I suspect that's what Munkul and Ttoks are saying in fewer words...

    Does the upper bolt hole still line up? If my theory is correct, even if you beat the thing back into the right angle, the bolt hole in your piece might be a bit too low to line up with the hole in the casting...
    I had 5 tacks spread out over the 3", Root was done at 140amps. 1.6mm filler.

    This is a complete custom set up, converting an old drum brake steering assembly to discs. There is nothing for the caliper to line up with other than be parallel and true to the rotor. This top bracket, coming off the top swivel bearing is my starting point. Once welded, I bolted back up and the caliper had moved quite noticeably.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Kelvin View Post
    Only thing I can guess is that the tacks (on inside corner) weren't big enough, so that when you then went and put in a big hot root on the outside corner, it softened or melted your tacks, allowing the shrinking big root weld to pull the upper piece downward (thus increasing your overlap from 1/16" to something greater than that) and moving your angle from 80 to something closer to 90 ... I suspect that's what Munkul and Ttoks are saying in fewer words...

    Does the upper bolt hole still line up? If my theory is correct, even if you beat the thing back into the right angle, the bolt hole in your piece might be a bit too low to line up with the hole in the casting...
    and just to add, the top piece was seated hard on top of the bottom piece, as in, it overlapped side ways, the piece with 4 bolts.

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    Re: Weld pulled the other way?

    Maybe I'm missing something, but wouldn't you want to tack on both sides to prevent movement ?


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    If you're only tacked on one side you should be able to adjust and then tack other side. Are you just filling on the one side(Red) ?
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    Re: Weld pulled the other way?

    Quote Originally Posted by albrightree View Post
    Maybe I'm missing something, but wouldn't you want to tack on both sides to prevent movement ?


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    If you're only tacked on one side you should be able to adjust and then tack other side. Are you just filling on the one side(Red) ?
    There is no room to get the torch in (red side)when it’s bolted in as pictured. Yes I had 5 tacks on the green side (not pictured). Then I unbolted it to weld out on bench, sit it upside down so red side is up and did the root run, and multiple passes until it was filled, checking the angle each time. I figured I would use the fillet weld to pull it back as I expected it to pull out. It did not, it pulled inwards (without the fillet)

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    Re: Weld pulled the other way?

    Did you put in the tacks on the green side while it was bolted up? Only other thing I can think of is that those tacks pulled the assembly from 80 toward 90 when you took out the bolts and allowed it to relax. In other words, if you put in the tacks while it was bolted up, the shrinkage of the weld "sprung" it -- and then when you pulled the bolts, it relaxed the spring and pulled in.

    You said you checked angle all along. Did you check it immediately after you tacked it (and released the bolts holding it in place, assuming it was bolted up when you tacked)?

    We're missing something ... it shouldn't pull the way you describe, as far as I know.
    Last edited by Kelvin; 4 Weeks Ago at 09:26 AM.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Kelvin View Post
    Did you put in the tacks on the green side while it was bolted up? Only other thing I can think of is that those tacks pulled the assembly from 80 toward 90 when you took out the bolts and allowed it to relax. In other words, if you put in the tacks while it was bolted up, the shrinkage of the weld "sprung" it -- and then when you pulled the bolts, it relaxed the spring and pulled in.

    You said you checked angle all along. Did you check it immediately after you tacked it (and released the bolts holding it in place, assuming it was bolted up when you tacked)?

    We're missing something ... it shouldn't pull the way you describe, as far as I know.
    Without seeing actual pictures of the tacks... how big they were how DEEP they were and things like that it's really hard to guess on anything I can tell you I have had things pull a long time after I checked them just from differences of how things cool... sometimes it can be several minutes before things change.

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    Re: Weld pulled the other way?

    Maybe I'm seeing things wrong but it appears to me it did exactly what happens when a bunch of weld is applied to one side of a joint with little weld on the opposite side. Only thing I see to do is grind out the thick weld and start welding by alternating sides equally so each weld is counteracting against the other. If the inside weld interferes with the two bolts/washers you can grind out enough to relieve this. Without sufficient weld on the inside it could start cracking on the outside weld.
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    Re: Weld pulled the other way?

    Might be a better idea to have a one piece bracket bent to the desired angle. It seems a little odd that the bottom piece has what appears to be 4 decent size bolts and the upright piece only has 1 bolt. Making a jig to hold the pieces in alignment is another option. There could have been stress from the tacking when everything was bolted and if you had good penetration on the root pulled in the direction of the tacks. Welds always pull on cooling and can take a minute or more.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Kelvin View Post
    Did you put in the tacks on the green side while it was bolted up? Only other thing I can think of is that those tacks pulled the assembly from 80 toward 90 when you took out the bolts and allowed it to relax. In other words, if you put in the tacks while it was bolted up, the shrinkage of the weld "sprung" it -- and then when you pulled the bolts, it relaxed the spring and pulled in.

    You said you checked angle all along. Did you check it immediately after you tacked it (and released the bolts holding it in place, assuming it was bolted up when you tacked)?

    We're missing something ... it shouldn't pull the way you describe, as far as I know.
    YES! it was tacked in postion, bolted up. (as per my first post)

    I let it cool fully (from tacking) checked alignment (in position, still good) unbolted, set bevel to angle (so I can check as I go)

    Then sat it on my weld table and welded the outside corner root run. It pulled a little from that first run, then more each run. But it pulled AWAY from the weld....

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    Re: Weld pulled the other way?

    Quote Originally Posted by Welder Dave View Post
    Might be a better idea to have a one piece bracket bent to the desired angle. It seems a little odd that the bottom piece has what appears to be 4 decent size bolts and the upright piece only has 1 bolt. Making a jig to hold the pieces in alignment is another option. There could have been stress from the tacking when everything was bolted and if you had good penetration on the root pulled in the direction of the tacks. Welds always pull on cooling and can take a minute or more.

    Lets not reinvent the wheel here....

    The four bolts are holding down a steering arm and also the king pin bearing. This is just attaching off it. How many bolts hold your calipers on your pick up? Two im guessing, one top and bottom, and Id bet your pick up is heavier than this. This design has been proven over 100 of thousands of Km on and off road.

    As for getting something bent up, its hard to bend thick plate like that in such small pieces with any accuracy.... Isnt that why we weld and inturn have this forum.

    The piece was let cool between runs. Each time, it pulled AWAY from the weld. I just figured with all the experience here someone would be able to say why?

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    Re: Weld pulled the other way?

    Quote Originally Posted by mla2ofus View Post
    Maybe I'm seeing things wrong but it appears to me it did exactly what happens when a bunch of weld is applied to one side of a joint with little weld on the opposite side. Only thing I see to do is grind out the thick weld and start welding by alternating sides equally so each weld is counteracting against the other. If the inside weld interferes with the two bolts/washers you can grind out enough to relieve this. Without sufficient weld on the inside it could start cracking on the outside weld.

    There is very little to no load bending the tab side ways (across the welds). When the brakes are applied, wheel rotation will have the caliper pulling down on the bolt end, so that 3" of weld will see compression on the bolt end and tension on the other end, in essence its all longitudinal to the weld.

    Yes any weld shrinks when cooled, some times you cant see or barely measure the distortion, but its there, if nothing else the stresses are. This shrunk AWAY from the weld. Thats what has me stumped!

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    Re: Weld pulled the other way?

    Quote Originally Posted by ronsii View Post
    Without seeing actual pictures of the tacks... how big they were how DEEP they were and things like that it's really hard to guess on anything I can tell you I have had things pull a long time after I checked them just from differences of how things cool... sometimes it can be several minutes before things change.

    Given the little overlap, the tacks were not too bad (small), but I was careful not to blow through the corner. It was let cool before removing, and between each pass when welding. Checking angle after cooling. It pulled from the root run, but pulled AWAY from the weld.

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    Re: Weld pulled the other way?

    Are saying it pulled "away" from the tacks 'cause that's what I see in your pics. That's understandable given the amount of weld opposite the tacks. By checking the angle every pass, by the third pass you should have been able to see what was happening and why. Like I suggested grind it out until you can bend it back to the desired angle or get it loose and start over. Only this time tack each side equally making sure it maintains the angle then make a full pass down each side and if you have one, use an air chipping hammer to peen each weld to relieve the pulling of the welds. Then heavily peen each pass on the outside corner to relieve stress pulling. If you're using a mig I'll suggest using 1/8" 7018 stick instead.
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    Re: Weld pulled the other way?

    Quote Originally Posted by mla2ofus View Post
    Are saying it pulled "away" from the tacks 'cause that's what I see in your pics. That's understandable given the amount of weld opposite the tacks. By checking the angle every pass, by the third pass you should have been able to see what was happening and why. Like I suggested grind it out until you can bend it back to the desired angle or get it loose and start over. Only this time tack each side equally making sure it maintains the angle then make a full pass down each side and if you have one, use an air chipping hammer to peen each weld to relieve the pulling of the welds. Then heavily peen each pass on the outside corner to relieve stress pulling. If you're using a mig I'll suggest using 1/8" 7018 stick instead.
    No.... it pulled towards the tacked side, when welding the outside corner.

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    Re: Weld pulled the other way?

    If you made a jig you could weld it and then heat it up and slow cool to stress relieve it. You attempted to weld it and it warped. Getting snarky when someone's trying to offer assistance isn't a good way to get responses in the future. Peening welds can relieve some stress but doesn't necessarily stop weld distortion on cooling. Over peening adds more stress. Peening has to be done when the weld is still hot.

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    Re: Weld pulled the other way?

    Quote Originally Posted by Welder Dave View Post
    If you made a jig you could weld it and then heat it up and slow cool to stress relieve it. You attempted to weld it and it warped. Getting snarky when someone's trying to offer assistance isn't a good way to get responses in the future. Peening welds can relieve some stress but doesn't necessarily stop weld distortion on cooling. Over peening adds more stress. Peening has to be done when the weld is still hot.
    Mate it’s very frustrating when the info is given, more than once and it still has to be repeated. If people did more than skim read we could all save time energy and frustration. The info is in the first post. The frustration comes from the responses going down a path that is the opposite to what happened and it getting further from the original problem and question. This is common on forums but seems to be very common here.

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    Re: Weld pulled the other way?

    I'm guessing it's because the root opening is very large putting a lot of heat on the opposite side. Due to less side mass I could see how it could pull that way. Putting 1 or 2 small strong backs before welding would definitely help.

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    Re: Weld pulled the other way?

    So..................of course it pulled towards the right side. It's the way the weld will contract when cooling. Not a real surprise here.

    Woulda pulled either way, even if you'd supported the heavy side (shrug)

    If you want straight, you gotta offset. Tack the joint offline...............not a 90, but an accute angle leaning to the left. You gotta anticipate the shrinkage.

    Cut it apart, and start over. Probably won't pull square if you add a bead on the left side.

    Put the stuff together with all the bolts, then tack it on left side. Take the bolts off that hold the heavy stuff, and tap the remaining piece over to the left a bit, then weld. It's a matter of judgement, and ya might wind up straight when done. It's a tough one.

    I sometimes do stuff that has to be straight. Usually I weld it first, as best as I can, then machine it.

    Fixturing won't get you there, it'll always be off a bit when it cools. Like I say......you gotta tough one going.

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    Re: Weld pulled the other way?

    Quote Originally Posted by M J D View Post
    I'm guessing it's because the root opening is very large putting a lot of heat on the opposite side. Due to less side mass I could see how it could pull that way. Putting 1 or 2 small strong backs before welding would definitely help.
    Ok. I’ll be making another one, that one is scrap now. It ends up with a back brace perpendicular to the upright, on centre between the four bolts. I had left that out for ease of continuous fillet weld and I didn’t want the upright bending under cooling ( which it may do) of the outside corner weld.

    It may be easier to set it all up, tack and then tap it over more to allow for shrinkage, given now I have an idea how much it will move

    Funny thing is, this is the second side of axle assembly. The other side pulled a little but no where near this side ( was easily able to adjust the caliper alignment with a couple licks of a file on the bolt mounting surface)

    **** just happens I guess ( but knowing why can help avoid it in future)

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