Avadon Posted March 10, 2017 Share Posted March 10, 2017 I'm trying to weld an inverted T shape (and failing horribly). My shop is full of things I've welded successfully so I'm curious what's going on. I've tried to weld this twice and now messed up a lot of material. Let me explain my process. I am trying to weld an inverted T shape. I put one side of the small part of the T-shape in the vice and weld the long piece so that's sticking up in the air (over my head) at 90dgs. But everytime I weld this, even if I use tons of clamps and braces the small part of the inverted T shape warps/bows upwards towards the long part. The material is 1.5x3" rectangular tubing with 1/8'th wall thickness. And I'm welding the broad side to broad side. I used angle iron at 45dgs to brace the long pieces so it stays dead perpendicular. But the problem is the either goes on one side or the other or sometimes equal on both sides and throws it all out of alignment. The material I used before was thinner and I blamed the warp on that. Now i'm using 1/8'th and it's still happening. I'm using tig welding and making very small tacks and letting it cool in between. But it seems that it's still warping the short piece. I thought about going up in wall thickness to something crazy like 1/4" but to me I think the problem would still occur when you pour enough heat in to get the weld it will still warp the piece since you're putting heat on one side and not on the other. I can't believe such a simple weld has perplexed me but I'm not sure I've welded much rectangular, or maybe it would happen with any material? Maybe the answer is to vice it to a desk or something flat with immense force in the hopes of counter acting the small piece from warping up? Or maybe heat both sides of the small piece before welding? I'm really at a loss since I've tried to complete this weld twice (with different material) and failed. Oh and I did think about clamps like this (below) pr even a clamp for "T" shapes but I don't think they'll stop the piece from warping. http://www.trick-tools.com/Deluxe_Welders_Angle_Clamp_Large_WAC45_1325 Link to comment Share on other sites More sharing options...
Glenn Posted March 10, 2017 Share Posted March 10, 2017 Can you tack or short welds one side, then tack or short weld the opposite side, to equalize any stress from the welding? Then come back and complete the welds in short sections, and on opposite sides, balancing the stresses as you go. Link to comment Share on other sites More sharing options...
Jim Coke Posted March 10, 2017 Share Posted March 10, 2017 Greetings Avadon, I would suggest clamping your tube stock in the T form to a flat plate first. Pre-heat the area to be welded evenly. If you have a MIG welder tack weld the sides first alternating for even heat . I would than tack the center of the T than remove the clamps and do the same on the bottom .. Check for square than pre-heat the area again and finish TIG welding the joints starting at the center of the joint evenly . Maybe John M will chime in with some suggestions I'm sure he has been there before . I wish you well in your project. Forge on and make beautiful things Jim Link to comment Share on other sites More sharing options...
John McPherson Posted March 10, 2017 Share Posted March 10, 2017 Long, convoluted answer including all the relevant physics and metallurgy: nah, ain't nobody got time for that. Short answer: Water is about the only thing that expands as it transforms from a liquid to a solid. Steel contracts with a force of 70,000 pounds per square inch. Ergo, warpage of the weldment. Restraint only goes so far, and still leaves residual stresses in the steel that need another step to address. Peening, post-weld heat treatments and flame straightening are all time-honored procedures in fab shops, Stitch welding and counter-welding are methods to help avoid and minimize warping from the start. Best advise: figure out how much distortion you are getting, and put that many degrees of axial tilt in the fixtures, so that it welds up to 90 degrees when cool. Sort of like pre-curving a knife blank downwards before setting the bevels, so that you don't end up with a banana. Link to comment Share on other sites More sharing options...
jeremy k Posted March 10, 2017 Share Posted March 10, 2017 This problem can easily be straightened after welding while still hot by backing up the short ends of the "T" and applying pressure on the opposite side of the weld (in the center of the short part) by press or hammer. The shortest answer I can supply: As John say's, the steel is contracting at the weld - so you have stresses on one side of the broad side and nothing on the other hence the bending. One needs to equalize the force on the opposite side by slightly bending in the opposite direction. Put a piece of 1/8" plate on each contact area to protect from marring/denting the surface during this. This can also be done with controlled heat straightening but that is more than I can explain via text. Link to comment Share on other sites More sharing options...
Avadon Posted March 11, 2017 Author Share Posted March 11, 2017 Thanks for all the great advice guys. I choose the easiest method, cut the existing structure apart and use it for scrap. Then I went and bought new material. The new material is the short part of the "T" and it's 3/8's wall, very thick stuff. I didn't have a lot of confidence in heating the old structure up and bending it back into shape like suggested so I scrapped that idea. I figured if I weld the long piece which is 1/8'th wall to the 3/8'ths material I should overcome the problem. But to be sure I took the 3/8's stock and I used a ton of clamps to clamp it to the desk. I also heavily clamped two 45dg angle iron members as suggested above and I clamped a brace to the back so it's butted up heavily and not going anywhere. Total I think was 10 bar clamps. haha It's not going anywhere. I also was very easy about the tacks this time. Put in 4 tacks, then cooled it all down. Then I went back and put in more tacks and then cooled it all down again. Tommorow I'll carefully weld it in, only doing small sections at all time and not making it very deep. It doesn't have to be the deepest weld as it's not holding much structure. This is the base of a "Eric Thing" forge. So there will be two other arms coming off that bottom T shape and casters will attach. The top long part of the inverted T will hold the cone like shape of the forge chamber. I've welded a lot of things before but never seem to run into this. Might be that most of the things I weld do not have disconnected ends on both sides and thus don't warp so easily. Thanks for the help, all. I'll know after I finish welding it tommorow if it still stays true Link to comment Share on other sites More sharing options...
bubba682 Posted March 11, 2017 Share Posted March 11, 2017 Now i know why i cant get any c clamps in canada lol you bought them all.What i would do is just tack in the temp bracing like ya did also if it warped i learned a nice trick years ago.Heat up the back side of the warp with a torch then get a bottle of water and start pouring it a little out at time on the heated side it will straighten you just got to play with the heat and water to get it where you want. Link to comment Share on other sites More sharing options...
Avadon Posted March 12, 2017 Author Share Posted March 12, 2017 16 hours ago, bubba682 said: Now i know why i cant get any c clamps in canada lol you bought them all.What i would do is just tack in the temp bracing like ya did also if it warped i learned a nice trick years ago.Heat up the back side of the warp with a torch then get a bottle of water and start pouring it a little out at time on the heated side it will straighten you just got to play with the heat and water to get it where you want. Haha I did. I have about a dozen of those HART clamps and I love them. Don't know if you can get them up where you are. That's a good idea. But I don't know how you'd get the torch to the back side. I like the idea of tack welding the 45dg braces. I thought about that but the clamps were on there so tight I thought it might be unncessary. I filled in the welds today and so far it looks really good. Only will truly know when I take off all the clamps Link to comment Share on other sites More sharing options...
bubba682 Posted March 12, 2017 Share Posted March 12, 2017 If it warps when you take the clamps and braces off lay it down and heat up the bottom then throw water on that side till it comes back to were you want it.I've used that trick alot makin weight liften gear for guys it works good.Usually once ya brace it and tack it it stays true usually lol.And how bought sending me up a few clamps lol...... Link to comment Share on other sites More sharing options...
Alan Evans Posted March 12, 2017 Share Posted March 12, 2017 jeremy k and bubba682 refer to heat straightening...I know the process as "heat triangles" so that may give another line of research / help with googling. Very effective process, I have bent and straightened Channels, RSJs and Universal Columns in both planes with it. The slight disadvantage in this instance is that it puts even more tension onto the weld area. But it is a quite normal procedure. A couple of similar sized weld beads on the back of the TEE bar (immediately opposite / in alignment with / and parallel to the tee fillets) can do the same job and be almost invisible if you grind a Vee first. If this is just for a base frame and is going to have castors why worry about the distortion anyway? It will be strongest left as laid and should not worry the castors. If it was sitting on direct on the ground a plate welded on as a toe at either end would prevent it rocking on the centre... Alan Link to comment Share on other sites More sharing options...
bubba682 Posted March 12, 2017 Share Posted March 12, 2017 Yes Allan you can back bead but me i find it easyier to heat it and eyeball it strait or when im feelin real craftsmanly i'll use a square lol..Plus its fun playin with the heat lol and i will also tack it to heavier material we call it strong backing here i find c clamps are useless once ya start pourin the weld to somethin.What do you think.. Link to comment Share on other sites More sharing options...
Alan Evans Posted March 12, 2017 Share Posted March 12, 2017 I tend to use Vise-grips for light stuff, G cramps (C clamps to you!) just for wood work but I invested in a few Carver clamps for serious metal work. Most fabricators use them over here, are they available on your side of the Atlantic? I suggested the straightening beads in case the OP did not have Oxy-Acetylene to hand...but its true...more fun playing with fire! Alan Link to comment Share on other sites More sharing options...
bubba682 Posted March 12, 2017 Share Posted March 12, 2017 Are you talkin about the the tables with all the square holes and those clamps i'll have to look em up to see if there the ones im thinkin of.Just went and searched them i ve never used that style we do use them along that style but i havn't worked in a fab shop in years so they might have the exact ones but i'm not sure.I might have to order a set give them a try. Link to comment Share on other sites More sharing options...
Alan Evans Posted March 12, 2017 Share Posted March 12, 2017 33 minutes ago, bubba682 said: Are you talkin about the the tables with all the square holes and those clamps i'll have to look em up to see if there the ones im thinkin of.Just went and searched them i ve never used that style we do use them along that style but i havn't worked in a fab shop in years so they might have the exact ones but i'm not sure.I might have to order a set give them a try. Not the table no...they are the orange two piece clamps with the shrouded screw and the notched coarse adjustment. Alan Link to comment Share on other sites More sharing options...
the iron dwarf Posted March 12, 2017 Share Posted March 12, 2017 carvers are great, I have lots of them up to 6 foot tall and weighing a lot more than I do, also the straight bars in all 3 weights and clamp heads to go with them though I mainly use the common standard duty ones Link to comment Share on other sites More sharing options...
bubba682 Posted March 12, 2017 Share Posted March 12, 2017 I'm goin to have get a set now lol just checked the price wow ,and can't find any in Canada but if those prices are real I'll be tackin scrap to keep things square they ain't cheap... Link to comment Share on other sites More sharing options...
Alan Evans Posted March 12, 2017 Share Posted March 12, 2017 It is a good investment, you will not regret. But I choose my words carefully...investment equals serious money! I have 6 of the slightly longer reach ones than Iron Dwarf posted and couple of the big boys with a straight bar to use for spreading. Alan The Carver Standard-Duty Long Reach Rack Clamps have many uses. The most common include welding, metal fabrication, moulding box and die holding, plate fabrication, plastic and fibreglass moulding and maintenance work. The Carver T321-250 Standard-Duty Long Reach Rack Clamp has the following specifications: Capacity: 250mm (10in). Reach: 120mm (4.3/4in). Overall Length: 360mm (14.1/8in). Clamping Force: 5,650N. Weight: 2.0kg. The standard reach ones like Iron Dwarf's have double the clamping force:- The Carver T186-300 Standard-Duty Rack Clamp has the following specifications: Capacity: 150mm or 294mm Reach: 60mm Overall Length: 245mm or 395mm Clamping Force: 11,300N Link to comment Share on other sites More sharing options...
bubba682 Posted March 13, 2017 Share Posted March 13, 2017 They are nice by but i couldnt find a supplier here, right now though im gettin ready to build a hydrolic press so thats goin to cost a few bob so after that ya never no ... Link to comment Share on other sites More sharing options...
arftist Posted March 13, 2017 Share Posted March 13, 2017 Couple things in general; Stainless stick welds great with far less heat imput. Pre bending the offending piece in the opposite direction works well. This can be as easy as clamping the tee bottom to a stout table at each end with a bit of .25" round bar under the center. Finally learning to straighten warped metal is critical to working stainless. It is spooky at first but becomes less mysterious with experience. Large dead blow hammers are an important bit of kit for the stainless fabricator. Link to comment Share on other sites More sharing options...
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