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I have a small project for a customer that I am doing and I need some help from the group. I welded some seat brackets onto a 1.5" sch 40 6061 pipe for a raft frame. They provided a jig for alignment to make sure that the loaction of the mounting hole will line up after welding. I was able to get them to fit the bracket after the first welding set. Once I fliped it over to finish the weld I could not get at while it was in the jig the pipe warped a little bit, now the holes don't line up and the pipe has a bow to it. Is there a way I can take out the bow in the pipe? That would make the brakets fit again and the pipe it's self need to fit into another fitting. Not sure if i can clamp it to a the table and apply heat or if there is anohter meathod. I tried to bend it back cold and did not do much.



Reply:Can you get some pipe with a close fitting inner diameter? Or a sleeve? And bend it.You could heat it or bend it some other way, but risk putting kinks in it.As much as possible these days i put a preset bend in stuff i know will warp. Like this job - I clamp the flat plate to the jig table with a bit of 6mm bar under the middle. Takes a bit of trial and error, but some of these came out perfect. The rest needed a slight amount of finesse after welding... with a press and a hammer.

Murphy's Golden Rule: Whoever has the gold, makes the rules.
Reply:Hey there,I have had very good results with flame straightening 2" steel box tube in the past. There are many videos on it. I am not quite sure how/if it will work with an aluminum pipe the same way though - I could see it going south very rapidly and uncontrollably once a certain temperature is reached - while the steel in the 2" box tube flowed pretty forgivingly. But - perhaps a combination of heating and mechanical straightening using a slightly smaller diameter pipe cold work - or - perhaps flipping concave side down, ratchet strapping the ends and heating in at the bend apex - then tightening a little etc. But again - not sure how easy this would be with aluminum...might end up with a flat spot........good luck. let us know what works - if anything.
Reply:Don't go at it with heat, you'll take out whatever temper the metal still has after welding. That can be straightened cold. Your pictured method didn't have enough force or leverage. Additionally, i'd support the pipe outboard of the brackets. Your distortion is going to be centered on the welds, that's where you'll want your pressing force on the top, not your lower support. Use soft wood or similar to pad the support blacks and the clamp. You don't want to accidentally dimple the pipe with point loads. If you've got a tube that loosely fits over the pipe, or fits inside, you can use that as a lever arm. If you have a table heavy enough, flip the thing over, where the outside of the end is even with the edge of the table. Clamp down the supported end, and use the tube as a lever arm pushing down. |
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