Recently I built wheel kits for two generators. The handles were U shaped hinged to a cross bracket on the end of the generator. The handles are I in.X 1/8 square tubeing mitered at the outside corners for a 90. I clamped the parts securely to the table and tacked outside of corners first then inside then on top. I let it cool for a bit -flipped it over-welded outside of mitre-flipped again and welded other side of miter then finished welding outside and inside of corners. The open ends of the handles came together aprox. 3/16 in. This was not a problem in this case because I welded on the hinge brackets after to fit the handle. I have had this happen before and its not a problem if I am fabbing the whole thing and can be worked around. Problem is if I have to fit to something existing. Wondering what I am doing wrong?
- LtBadd
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You're not doing anything wrong per say, this is the reaction of the stress introduced by the welds. You don't say but I presume this is steel tubing.
In the future you can adjust the cut of the angle to allow for shrinkage. I believe Jody has a video where he addresses this issue and shows a welding sequence to minimize the effects of distortion.
I wish he had a method to index the topics in the videos, making such things easier to find.
In the future you can adjust the cut of the angle to allow for shrinkage. I believe Jody has a video where he addresses this issue and shows a welding sequence to minimize the effects of distortion.
I wish he had a method to index the topics in the videos, making such things easier to find.
Richard
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Thanks. Yes it is steel tubing. I think you are suggesting widening the mouth of the U a bit to compensate which would help. In this case each part of the frame is only 12in. I am wondering if it is more of a problem with smaller material. I just welded a yoke ( rear trailer frame -2-2X4X1/8 side posts to a 2X3X1/8 cross frame ) again U shaped and it only deflected in 1/16in using the same sequence. this was also welded flat clamped to the bench. Did I get lucky 
Homeboy,homeboy wrote:Thanks. Yes it is steel tubing. I think you are suggesting widening the mouth of the U a bit to compensate which would help. In this case each part of the frame is only 12in. I am wondering if it is more of a problem with smaller material. I just welded a yoke ( rear trailer frame -2-2X4X1/8 side posts to a 2X3X1/8 cross frame ) again U shaped and it only deflected in 1/16in using the same sequence. this was also welded flat clamped to the bench. Did I get lucky
Every weld you do is different, you will NEVER have 2 welds exactly the same, its just impossible so depending on the heat, angle, argon flow or wire speed or whatever you are using, it all matters. What the temperature is where you are working, how the piece is laid up, all those things play in so its not that you got lucky, its just different.
In most cases you can just pry it back if you need to, Whenever I build stuff I don't worry too much about warping, only during tacking because as I go along welding things onto it, parts of the frame will shrink and expand and its just how it goes, I don't have a magic genuie to tell me which sequence to weld in, but I do have a bunch of steel pipes and pry bars to get em straight again
if there's a welder, there's a way
Simple tactics: brace the parts (install a temporary brace between the legs) while you weld. Or even tack the legs while you weld to hold them. Once cooled, cut them loose. Keep thin walled tubing firmly secured during fit up, tacking, welding and cooling. It pulls and twists a lot more than you realize.
You can also change the sequence (as was mentioned) to evenly pull the part as you weld. Frequent checking with a square or level helps. Slowing down and not trying to "get it done" also reduces the distortion by applying less heat for shorter durations. The more you weld, the longer you weld, the hotter parts become, the more they move. Sounds obvious, but it takes real discipline to wait to prevent it. Especially when you're staring at 15 seconds of welding you KNOW you can whip out and make progress. Use the idle time to prep or fit up the next batch. Jump around with your work and you'll see a marked difference.
You can also change the sequence (as was mentioned) to evenly pull the part as you weld. Frequent checking with a square or level helps. Slowing down and not trying to "get it done" also reduces the distortion by applying less heat for shorter durations. The more you weld, the longer you weld, the hotter parts become, the more they move. Sounds obvious, but it takes real discipline to wait to prevent it. Especially when you're staring at 15 seconds of welding you KNOW you can whip out and make progress. Use the idle time to prep or fit up the next batch. Jump around with your work and you'll see a marked difference.
Here is the video with Jody and although it is shown with a square tube (not mitered square tube), you can gain some valuable info by watching it. 
https://www.youtube.com/watch?v=0pf-qQDslhU
Like all the others have said, it can be controlled but it takes a little thinking and some luck to find the correct formula.
https://www.youtube.com/watch?v=0pf-qQDslhU
Like all the others have said, it can be controlled but it takes a little thinking and some luck to find the correct formula.
Thanks for the help. I did watch the video and it was very informative and I see there are more videos which I am going to watch when I have time. Nice to know I am not a total klutz and now I will play around and see if I can improve a bit. The lazer pointer demonstration was genius. As I said this is not a real problem for me but I am always trying to find a better way and there usually is. 