OK, I just don't get it

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I'm just a light hobbyist welder, I've got a Millermatic XP130 w/ flux core wire only. A couple months ago, I built a two barrel trash can cart with wheels that I can pull my trashcans out to the street on trash day. I tried hard to make everything with exact sized cuts and to square everything as I went. Regardless, the finished project has a slight bow to it, the left front wheel and back right wheel teeter-totter maybe 1/4 inch. Now for today. I''m building a deer hunting box blind, 5' x 5' square and 6' tall. Once again, I measured everything twice, used a bubble level and a square to get everything square and straight. I've got the floor framed and welded, the 4 corners poles square and welded and the top is framed and welded, all out of 3/4" 14ga square tubing (just like the cart was built out of). Just like the cart, the front left and back right corner teeter-totter back and forth about 1/4"..... WTH is causing this ?
Reply:Metal shrinks when it is welded and it will draw itself in different directions.  it is something that you have to learn to overcome. Ever wonder why three legged tables are so popular?Two turn tables and a microphone.
Reply:It helps to restrain the frame work when welding. Just clamping it to a welding table eliminates a bunch of the problems. Then you need to learn how to straighten things with a torch or mechanical force. Post up a picture of your frame and I may be able to help you figure out how to straighten it out.
Reply:The order of welding and learning how to weld things and keep control of shrinkage and warping is not taught in many welding schools. That is ONE of the things that makes a good welder. Not just running a nice bead but knowing which weld first and if there will need to be back stepping etc.,.I would like to teach that if a opportunity came up.AWS certified welding inspectorAWS certified welder
Reply:Originally Posted by rico334I'm just a light hobbyist welder, I've got a Millermatic XP130 w/ flux core wire only. A couple months ago, I built a two barrel trash can cart with wheels that I can pull my trashcans out to the street on trash day. I tried hard to make everything with exact sized cuts and to square everything as I went. Regardless, the finished project has a slight bow to it, the left front wheel and back right wheel teeter-totter maybe 1/4 inch. Now for today. I''m building a deer hunting box blind, 5' x 5' square and 6' tall. Once again, I measured everything twice, used a bubble level and a square to get everything square and straight. I've got the floor framed and welded, the 4 corners poles square and welded and the top is framed and welded, all out of 3/4" 14ga square tubing (just like the cart was built out of). Just like the cart, the front left and back right corner teeter-totter back and forth about 1/4"..... WTH is causing this ?
Reply:Walker-  Here's a couple pics. The first pic, the red dots in the corners are the sides that teeter-totter just a bit, the blue dot sides are equal. I'm thinking of hanging heavy weight from the top corners of both red sides when I put the siding on, hopefully if planned right, this maybe should take the warp out it when they're secured to the frame.
Reply:As a hobbiest, you won't have much experience with distortion/weld pull, but the more you do, the more you will learn how welding sequence can minimize, if not eliminate it altogether. Use cross bracing or gussets wherever possible.Practice by tacking a number of uprights to a length of your 3/4" tube,Tack them nice and square, and observe the results when you weld them in place. The first weld will cause them to lean in that direction and the tube will bow upwards. Once you get a handle on the warping, you can place uprights on both sides of the tube, and sequence your welds to keep everything nice and square and straight.Nobody can teach you in a few minutes, but with practice, you catch on. I actually find it easier to start with a frame that is slightly out of square and pull it into shape as I weld it out, than to start out with one that is bang on and have to keep it that way. Good luck!
Reply:Originally Posted by dave powelson4-fabricators waste all kinds of silly time, anticipating distortion, checking tack up, fit up, distortion, measuring things by more than one method, making corrections as the weldment progress.checking and compensating square readings against diagonal measurements. Some of them--actually use or make their own shop layout drawings--talk about waste of time!
Reply:Its called preheating and post heating look it up thxHobart mega arc 250 Airco dipstick160 air liquide cutting torches arc air gouger and so many more goodiesIf you cant dazzle them with brillants baffle them with bullsh$t
Reply:Not that it has to be this fancy.Just use welded nuts and bolt leveling feet.http://www.carrlane.com/catalog/inde...3C3B2853504055