Need help with pull welding

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I'm a hobby welder and should have known better but I was rushing Ok I screwed up and put a little too much heat and pulled this frame from being flatIt is still square but the back left corner is lifting off the tableI need to know which side of that corner I should weld to pull it back flat. Do I weld the top side or the bottom side? I'm open to other solutions too that hopefully don't include cutting the frame lolBtw I'm building an electric radio flyer go kart so I'll post more as I go along after I fix this
Reply:I think what's happening is that all four corners want to pull inward. Thats because there's more weld contact area on the inside corner welds than the outside ones. They want to be something like 89 degrees instead of 90. But that can't happen, so the frame equalizes the strain by turning "pringle" shaped.Do you have a hydraulic jack? You might be able to relieve some of the strain by placing the jack widthwise inside the frame, about a foot from the rear end, Then you cut a short piece of that 2x4 as a spacer block if you need it.  also do this with the front end as as well.  See if that brings it back into square. There are other methods you could use, for example, get creative with a 5 lb smith hammer.  Other things I'm thinking of involve tack welding parts of it to a large-size scrap of leftover I-beam. then using a pry bar. But I don't think you have any large I-beam laying around, unlike myself.Last edited by Joshfromsaltlake; 04-13-2012 at 06:59 AM.
Reply:Do you have a torch?
Reply:Put the frame down on concrete and  place  short pieces of 2x4 under each corner except the high corner.  While someone stands on the far corner you stand on the corner that is free and push it down with your weight.  Take it slow or you might over bend it.  If you need more bending then double the thickness of 2x 4  to 3 inches and try again.
Reply:Thanks for all the replies so far. I don't have a torchI suppose I could just bend the frame back to flat that was my first thought but I thought there might be other ways people would do it so just tryin to learn more than one way
Reply:Lacking a torch, I've sometimes had luck with "back beading".  You weld on the opposite side of the joint that made it pull in the first place.  Sometimes it works, sometimes it doesn't.  Adding some force to pull it in the right direction, while welding, will sometimes make it go back to where you want it.Determine which direction it pulled.  Then do the above.I would imagine the pulling occurred at one of the circled joints, you'd weld on the side that's facing the table top.  And you'd sometimes have better luck if you welded just off to the side of the joint, towards the side you want to pull.  You can grind the weld off later."Any day above ground is a good day"http://www.farmersamm.com/
Reply:ie. turn it over, put a brick or something on it to hold it flat, then weld at the right areas after you've determined which joint messed up"Any day above ground is a good day"http://www.farmersamm.com/
Reply:the brick doesn['t have to squash it flat, but enough weight to persuade it to bend when heated/cooled"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Farmersamm - that's sort of what I'm trying to understand. So say the corners circled are the only corners not touching the table. Do i weld on the side facing up or the side facing down?I plan on clamping it down to help persuade it in the right direction while welding once I figure out the right side. Thanks for your input!
Reply:Welds shrink.
Reply:Daddy - so with that I'm gonna assume I should weld the top which should shrink/pull it together back flat
Reply:I'm just learning, so take this with a grain of salt. But I thought welds shrink towards the weld. So if you were welding beads left-right on top of a flat sheet, the sheet would end up bowing upwards. The top and bottom ends of the sheet would move up, away from the table. If I have that correct, I would have thought you'd want to weld the *bottom* side of the frame, not the top side, to pull it back down? Please correct me if I have this wrong.
Reply:It's kind of hard to give specific advice on this without seeing it in person, but I think lotechman's approach is what I would try first.  Samm is giving you more ways to try, but he also says you have to understand where it failed/pulled. The corner that is in the air may not be the one that pulled. Again, without seeing it, hard to say.
Reply:This might helpThe weld does indeed shrink, it's the principle behind back beading.  It can pull it back to where you want it.  Sometimes you need to do a few welds along the arc to really get a nice job, but sometimes just the one will do"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by daddyIt's kind of hard to give specific advice on this without seeing it in person, but I think lotechman's approach is what I would try first.  Samm is giving you more ways to try, but he also says you have to understand where it failed/pulled. The corner that is in the air may not be the one that pulled. Again, without seeing it, hard to say.
Reply:DSW, is there a suggestion for how to at least minimize that warping? Say you're making a square frame, similar to cboy's. Could you, say, tack the inside and outside corners on top, then flip it over and do the same for the bottom. Then go back and do all the welds for real? Would the tacks help at least hold it square, without adding too much heat in the process? Would clamping it down while welding help? Or would it simply hide the warping until you remove the clamps?
Reply:Originally Posted by RedOctobyrDSW, is there a suggestion for how to at least minimize that warping? Say you're making a square frame, similar to cboy's. Could you, say, tack the inside and outside corners on top, then flip it over and do the same for the bottom. Then go back and do all the welds for real? Would the tacks help at least hold it square, without adding too much heat in the process? Would clamping it down while welding help? Or would it simply hide the warping until you remove the clamps?
Reply:Originally Posted by RedOctobyrDSW, is there a suggestion for how to at least minimize that warping? Say you're making a square frame, similar to cboy's. Could you, say, tack the inside and outside corners on top, then flip it over and do the same for the bottom. Then go back and do all the welds for real? Would the tacks help at least hold it square, without adding too much heat in the process? Would clamping it down while welding help? Or would it simply hide the warping until you remove the clamps?
Reply:Google "flame bending"You can do the same thing with the heat from an arc welder.
Reply:Doug makes a great point about fitup. It is likely that a small difference in the gap between your parts caused the joints to contract differently, leaving you with the problem. Perfect fitup is really important to minimize the effects of shrinkage.
Reply:How much is it actually warped. If this is going to be a go kart is there anymore major frame work that needs to be done. I have fixed a few go karts for some kids that I didnt build and it seems like they are generally pretty warped from just the abuse they take. I can understand wanting stuff flat, God knows I have spent hours making things flat using many of the suggested ways above but I guess im wondering if its worth it to spend a bunch of time making it strait if after the first hard bumb it slightly twisted again. Cool project by the way looking forewrd to more pics.DSW lots of good info.Last edited by KD Welding; 04-15-2012 at 10:04 AM.
Reply:thanks again for all the great feedback. DSW - i actually tacked up everything being really careful to keep it all square realizing it would pull some. I was doing so good too, then i rushed the last few joints cause i was getting tired and when i unclamped from the table i realized i screwed it up. lol I appreciate your diagrams, that helps explain clearly what i was sort of imagining in my head!I will be trying to figure out which side needs to be flatened this week using some of the suggestions here.sbchp355- you make a good point about if its going to get tweaked after the 1st ride. I hope not but its entirely possible.The kart will have another cross bar in the middle of the frame in front of the rear axle after i mock up and tack in the rear axle mounts. other than that it will have just some tabs welded in to mount the radio flyer tub.The next step is getting my rear axle setup all put together and mounting it. Then I will figure out what kind of rake i'm working with to mount my front spindles.Will post more as i continue Last edited by cboy; 04-15-2012 at 02:57 PM.
Reply:Cut it straight,or mitre, and tack it right to begin with, then work at it peening the welds with your chipping hammer right after welding.Try not to over weld.Last edited by pistolnoon; 04-23-2012 at 03:11 AM.