Avoiding distortion on square tubing frames?

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So it seems every time I make a simple frame type shape out of square tubing, it distorts on me and doesn't lay flat anymore.I am literally talking about putting 4 mitered pieces of 1" tubing together in a square and welding all the edges. (using MIG)The order I welded it in was 1. tacked all edges2. inside corner fillet welds3. mitered edges welding away from the inside corner.4. outside edge.What am I doing wrong here?www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:You really need to build some sort of jig for holding things like that square and straight. I make mine where I can complete most of the welds beyond just the tacks. I should add that nearly everything gets clamped in some fashion while welding, even if it has already been tacked. Even if you have to shim under it to allow for weld beads. Welding away on lighter things with out clamping is asking for warpage. Attached ImagesLast edited by Sandy; 11-05-2014 at 10:55 PM."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:I have know idea, but its good to hear you have a procedure!the procedure I adopted (because I was taught this way)tack outside top and bottom, square, tack inside top and bottom, weld outside corners, weld top, flip and weld bottom, and do inside corners last.reason being that in theory*, the inside fillet weld has the greatest potential for warpage, and the outside corner weld has the smallest potential for warpage. start with the smallest and finish with the biggest. so that when you get there, your already "locked in"another bonus to that procedure is that your two corner welds end up being welded in opposite directions, which may mean jack-shoot lol, I don't know because that's all I have ever done. with small tubing, taking the offending corners and slamming them on the concrete floor to get the wobble out was highly effective, but rarely necessarybosses stuff:trailblazer 325maxstar 200my stuff:sa 200fronius transpocket 180100 amp Lincoln w/f97 f350 DITKevin
Reply:I had it clamped to my table but the problem is my table is more of a workbench style, its wide and narrow so only about 2.5' deep. I can't fit the entire thing on it to clamp it all down in one shot.www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:and another note on my procedure above, it only works effectively if you slightly over-miter ( I always aimed 45.5 deg) your cuts to guarantee no inside corner interference to meet inside/outside dimension requirements. but that is always marking/ cutting to the outside of the miter.opposite would apply if marking/ cutting from inside.that brings up another point that if your saw makes nice miters, but doesn't make them strait down, your in for some wobble. hows your saw?bosses stuff:trailblazer 325maxstar 200my stuff:sa 200fronius transpocket 180100 amp Lincoln w/f97 f350 DITKevin
Reply:You need to understand how metal pulls when you weld it. If your corner is set at 90 and you weld the inside corner, it will pull towards the weld and right away your corner is now less than 90 deg. There are a number of ways you can combat this. #1 you can tack all 4 corners of a joint ( 2 on each side of the tube) and check square. Then weld. I'd tack the sides vs the inside/outside edges. ( see #2) #2 If you weld on the sides vs the inside/ outside corners, the angle will stay square, but it might twist some. That would be because the weld would pull the pieces "up" rather than towards the corner leaving the corner at 90 deg. #3 You add some "extra" to your corner angles. Since you know if you weld the inside angle it will pull towards the weld, you set up the angle at say 95 deg vs 90, so the piece is splayed away from the corner. Now when it pulls the piece pulls straight. It takes a bit of practice and testing to figure out how far something will pull when welded. Some guys will set the outside tight lets say, then gap the inside 1 /16" and weld. When it pulls, the outside opens up to a similar gap so it will be square when you weld.#4 Gapped tacks. Rather than but everything up super tight to begin with, leave yourself some room when you tack. Similar to what I just described, set things up so there is a 1/16" gap. Tack the corners on the inside ( or outside) 1st. Check square and see where things need to go. Since the tacks are small and you have a gap, you can  pull/push the pieces back to 90 and tack again.#5 Change the joint design. Not as easy with square tube, but easier with angle iron. Instead of cutting miters, cope the joint. Now instead of welding inside/outside, you are welding at 90 deg to the corner, With tube, you'd have to cut 3 sides of the tube away and leave 1 "flap" sticking out, then cut the other piece short by the thickness of the material. Now the material will help hold against pulling the corner better than on a miter. Tack where the flap starts on the outside where the two pieces meet. Than tack inside corner or outside corner, then the other corners..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I've taken that clamp and others and welded one corner at a time and when you get to the last corner it'll be a fraction off for the last two fitting together. All you have to do is smooge them together, clamp and weld. It'll lay flat too except for where the beads hold it off the table. With a decent jig it doesn't matter where the rest is at. You're only interested in what is in the jig. It helps to weld opposites (top then bottom) (inside then outside)."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Originally Posted by BrooklynBravestI had it clamped to my table but the problem is my table is more of a workbench style, its wide and narrow so only about 2.5' deep. I can't fit the entire thing on it to clamp it all down in one shot.
Reply:Also should probably mention I am using an abrasive chop saw. Not ideal by any means for making miters... The corners of the particular piece i was assembling were acute. It screwed up the dimensions of the square shape by 1/8" all around. But it was an even 1/8" so I don't think it will cause me any trouble on this one. Over mitering next time is a much better idea then allowing it to be under...www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:Ever notice after its all tacked up and you have welded the first outside flat face that if you allow it to cool it will not be square to it's mating part.  But after welding the other opposing side it will pull itself back to pretty much square.  Metal moves when heated to liquid and cooled, you have to learn to use that to your advantage.  Good luck......Measure with a micrometre, mark with chalk,  cut with a torch.Never force anything...just get a bigger hammer.RoyOld Airco buzz box approx 1974Lincoln mig pack 15Lincoln 175 square wave1954 9" south bend lathe
Reply:I have a Bessey right angle welding clamp (WSM-9) and it works great for building frames.
Reply:Chop saws almost never make accurate miters to begin with. The blade always tends to wander or walk. Some guys will scribe their actual cut line, then rough cut with the chop saw and then sand/grind to the scribed line.  Big stationary disk sander is perfect for sanding corners to 45 deg. I know others who try to "fudge" the way the saw walks and compensate on the fence. They'll cut a test piece and check it for 90. If it's off by say 1/16" on the inside edge, they'll adjust the fence a bit positive, then take another test cut and see if they are closer to 90 deg.  I've also seen guys who will do what I suggested at the end of #3 above and use the off mitered cut to their advantage. They'll fit things up and leave the gap say on the inside, then when they weld, it pulls straight and they can weld the outside up..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:When it comes to building things out of square tube and having them end up with a high degree of square-osity there's way more to it than just the welding.   As DSW and some others here have already mentioned the first critical step is cutting all your parts just as accurately as possible.   No amount of welding skill or complicated welding sequence will ever compensate for a poor fit up.   Besides getting your saw set up right and learning how to use it so that you can get repeatedly accurate cuts efficiently you also need to have a decently flat table top to work off of for fitting up on and a large selection of clamps (and other aids) to hold things in place for tacking.   In general what I like to do is get as much of an assembly tacked up as possible before beginning to weld it out.  Often times this entails getting some of the parts tacked up into smaller sub assemblies and then fitting them together into the larger weldment.   You need to have a flapper disc on a grinder handy to flatten off some of the tacks so that when you flip things around they'll clamp back down flat to the table.   You also need to watch your table top surface to make sure you don't have spatter balls under parts you're trying to clamp flat.When it comes to the welding sequence I always try to make all the butt (mitered or square) and out side corner welds first.   I save the inside corner (fillet) welds for last and then always try to make them in opposing pairs so that they offset each others tendency to pull things out of square.   The whole time I'm welding out I've got a square handy and am constantly checking things to help me decided where it is I want to weld next.   And as much as possible I like to keep things clamp hard to the table while welding.
Reply:Originally Posted by HT2-4956When it comes to building things out of square tube and having them end up with a high degree of square-osity there's way more to it than just the welding.   As DSW and some others here have already mentioned the first critical step is cutting all your parts just as accurately as possible.   No amount of welding skill or complicated welding sequence will ever compensate for a poor fit up.   Besides getting your saw set up right and learning how to use it so that you can get repeatedly accurate cuts efficiently you also need to have a decently flat table top to work off of for fitting up on and a large selection of clamps (and other aids) to hold things in place for tacking.   In general what I like to do is get as much of an assembly tacked up as possible before beginning to weld it out.  Often times this entails getting some of the parts tacked up into smaller sub assemblies and then fitting them together into the larger weldment.   You need to have a flapper disc on a grinder handy to flatten off some of the tacks so that when you flip things around they'll clamp back down flat to the table.   You also need to watch your table top surface to make sure you don't have spatter balls under parts you're trying to clamp flat.When it comes to the welding sequence I always try to make all the butt (mitered or square) and out side corner welds first.   I save the inside corner (fillet) welds for last and then always try to make them in opposing pairs so that they offset each others tendency to pull things out of square.   The whole time I'm welding out I've got a square handy and am constantly checking things to help me decided where it is I want to weld next.   And as much as possible I like to keep things clamp hard to the table while welding.
Reply:One of the handiest things I've got to help with fit ups is a heavy piece of angle iron that I had a machinist square up on the mill for me.   I took him a 30" piece of it and after he milled it I put it in the saw and cut off a half dozen 2" pieces from it.  You can see where I'm using two of them in the above picture to hold things square and in place for tacking.   As far as I'm concerned those magnetic holding tools they sell for  doing this are nothing but a huge PITA to try and use.   I pretty sure I'll never waste any money buying any of them ever again.  Another handy tool I can highly recommend is that modified yellow 4" wide chisel you see laying on the table.   If you run it against the belt sander to get rid of the chisel point and make the end square (like you sharpen a putty knife) it makes a great tool for not only keeping the table top spatter free but also cleaning up any spatter beans on what your working on.   Next to the clamps it's probably my most used hand tool.   I even prefer it over a regular chipping hammer when stick or flux core welding.
Reply:May have already been said, but...............don't weld it all up too fast.
Reply:Originally Posted by BrooklynBravestSo it seems every time I make a simple frame type shape out of square tubing, it distorts on me and doesn't lay flat anymore.I am literally talking about putting 4 mitered pieces of 1" tubing together in a square and welding all the edges. (using MIG)The order I welded it in was 1. tacked all edges2. inside corner fillet welds3. mitered edges welding away from the inside corner.4. outside edge.What am I doing wrong here?
Reply:This picture helps show more of how I tack things up in smaller sub assemblies and then start combining them to get the finished item.   These two corners you see sticking up in the air were both tacked together from the two pieces that make them up while they were clamped flat to the table.  Notice I only tacked the two out side corners of each one.   Next I had to make the two inside halves of the mitered butt welds (and then flap disc them flush) before fitting in the horizontal member that went between them.   But I got that horizontal member fit and tacked in there before doing any of the rest of the welding you see in the second picture.  Those welds were made in place (down hill) with and .035 wire run in pulsed spray mode.   That horizontal member was the last piece that went in to that frame and that's why I started welding things out.  If I'd of had more main pieces of the puzzle to go I wouldn't have made those welds until I got them tacked in/on.
Reply:Wow your fitup is truly flawless.You bevel all the ends with a flap disc I guess? I assume they're also bandsaw cut.www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:Brooklyn,I wouldn't go so far as to say my fit ups are  "truly flawless" but I do put considerable effort in to making them just as accurate as possible.   A 60 grit flap disc on a 4.5 inch grinder is definetly your friend when doing this kind of work.While those pieces were cut on a band saw there's no reason you can't get just as good a fit up using a 14" chop saw to cut your pieces.   It's just not as efficient (production wise) because you've got to pay a lot more attention to the small details when using a chop saw to make sure all your pieces come out like you need them to.   Another really handy piece of equipment to have on hand for this kind of fabrication work is a belt sander.  It's the best thing for that last little bit of fine tuning of the angles and lengths of parts (especially when using a chop saw).
Reply:Originally Posted by BrooklynBravestI had it clamped to my table but the problem is my table is more of a workbench style, its wide and narrow so only about 2.5' deep. I can't fit the entire thing on it to clamp it all down in one shot.
Reply:Would something like this work on metal?http://longisland.craigslist.org/tls/4741837513.htmlwww.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:Some times if some things to big for the table you have to tack part of it up, reposition it and then tack the other half up.   You can have parts of it hanging off the table and still be able get things squared up and clamped securely with the aid of some other pieces of material.   Some times to big of a table can be just as much of a PITA as to small of one.
Reply:Originally Posted by BrooklynBravestWould something like this work on metal?http://longisland.craigslist.org/tls/4741837513.html