angle iron?

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Hey folks Ive looked around on here for a while, but this is my fist post. I have done a good bit of welding, but one problem I always have is warping, and twisting. What can I do to help prevent this? I will give my latest example, welding a shelf out of 2"x2"x1/8" angle iron. the shelf is 2' wide by 16' long with a brace running across it every two feet. I started on one end welded the back side of the first brace, on say the right side, then went to the other end and welded the front left side. I dont know if that made any sense but I went from one end to the other criss crossing, working my way to the center, and it twisted. If any of yall could tell me where I went wrong, or what I need to do differant it would be greatly appreciated. Thanks for your time.
Reply:Put your work in a jig that will prevent any warping! remove it after it cools.AEAD 200LE, Lincoln precision tig 185, Millermatic 251, Spectrum 625 extreme, Victor torch , Smithy 1220LTD. and  Do all C-4 band saw ,  Always adding.
Reply:I would like to order five of these anti-warping jigs. I would also like to order one for Stick-Man's brain.  Last edited by tbone550; 02-01-2012 at 09:54 PM.Reason: Added to my order :)
Reply:Diagonal bracing most likely would have stopped things.  If you tack welded a couple of 8 foot pieces diagonally across the framework you would have had better luck.  From your description you created a series of rectangles.  By creating some temporary triangles across the frame you stop things from moving.  Once cooled snap the bracing off.  A rectangular shap will hinge and move but a triangle is limited by the length of its sides so it cannot hinge at the corners.
Reply:You must fust undastand, Gwassshoppa, Misa Swrink is vewy stwong. Warping is gonna happen no matter what, when you weld something it's going to shrink and warp. I think you know this already, when you mentioned how you tried to move around to avoid the warping. What you need is a plan of action that will, ideally, cancel all the shrinkage. Try to plan for the direction the shrink will move your joint and then counter it with the opposing joint. It sounds like your plan was exactly opposite of what it should have been. When welding up a ladder shape you should move steadily from one end to the other, finishing each "rung" with a consistent and correct pattern, not jump from one end to the other.It is impossible to hold material that thin in a jig, then weld it up, and expect it to stay. Especially angle iron, square and round tube give you great torsional rigidity, angle has very little. I'm guessing your shelf is fairly flexible in twist, until you get it bolted to the wall. So, I'd say, don't even bother with a jig or clamping it down, other than just holding where you want it, just lay it on a table or saw horses and you will get a better idea of what the warping is and how to deal with it. Also, the direction you weld each joint will have a huge impact on the direction Mr. Shrink will pull. If you could post a picture of the shelf, and explain the order and direction you welded each joint. I think I could tell you how and why it twisted.Last edited by fortyonethirty; 02-02-2012 at 12:22 PM.Ian TannerKawasaki KX450 and many other fine tools
Reply:Gave my last copy of Mr Shrink away.  It was on VHS.  Is it availble anywhere nowadays??
Reply:Clamp it down to a steel table before welding, it will eliminate a huge amount of shrinkage issues.
Reply:The Lincoln bible has an entire section about warpage,  what causes it and how to use or control it. Overwelding increases it without doing any real good, peening a weld while still hot can reduce it...but explaining all the aspects here is beyond me right now so I'd suggest your looking at that book would be the best way to learn some of the basics.