Flame Straightening

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Hello, I am totally new to this forum. I am building two ice fishing house skids out of 6" x 3"  1/4 wall tubing. They are 24' long and the 6" dimension is placed vertically. After welding the necessary add ons, the lengths of tube have bowed laterally and I would like to try flame straightening them. I have been searching online for books or just good information and you'd think I was trying to find out how to build a space shuttle. In fact I would probably have better luck finding information on how to do that. Ha ha. Anyway, I am hoping some awesome welder out there would be kind enough to give me some information on how to do this right. Thanks, Bryan
Reply:OK --- Short course in straightening.Material needed: 3' long piece of the tubing that needs to be straightened (drop off / scrap piece).Oxy/Acetylene torch with a Victor 0324-0110 6-MFA-1 HEATING NOZZLE or equal.Spray bottle full of water.Block up your tubing. Heat a "wedge" shaped area until it's red hot. See photo.Spray the water on one side of the tubing (The side you want to shrink).... Continue the process until the tube is straight.Thanks,Hobo Attached ImagesLast edited by hobohilton; 09-12-2012 at 07:07 PM.Lincoln SA200's... at least 15 - 20. They come and go. Growing partial to the "Short Hoods" in my old age. Last count on Short Hoods was 13 in possession.
Reply:Hello wanbry, I will try to attach a link to some of the better documented information concerning straightening, bending, etc. as it relates to welding. I have the John Stewart book in this link it is a really good reference and read. Good luck and best regards, Allanhttp://johnstewartbooks.weebly.com/ Sorry, I noticed that it is rather pricey so you may wish to see if a local library or other resource might have a copy that you could go check out or read. I should add that hobohilton has given you some good information as well, not to take anything away from him. When I do my shrinks on tubing I use spots on the bottom face of the tube that is opposing the internal bow as opposed to a wedge. Just a personal difference and the way that I was shown/taught. General rule: a spot/area that is heated will expand, but then as it is cooled it will contract slightly more than it initially expanded.Last edited by aevald; 09-12-2012 at 07:19 PM.aevald
Reply:wanbryIn addition to the recommended references; in practice the key to effective heat shrinking is rapid heat-input.  Is is a kin to using a hammer.  You don't beat something to exhastion with a small hammer, you hit it once with the appropriate weight hammer.You have to exceed the effective shrink temperature before the heat is conducted away. The heat in-put rate has to exceed the dissipation rate in a very consentrated area; and in a manner of seconds. If you use too small and/or too few rosebuds all you are doing is burning fuel. On 6 x 3 x .250 tube I wouldn't take this job unless I had two Victor Journeyman size rosebuds on big bottles - two rigs, with a garden hose.  So equipped, it is play  -  not work, because you get results.Opus
Reply:Lincoln has a small book entitled "Metals and How to Weld Them". It has a very short but very informative section of the effects of heat in a small zone and the surrounding areas under compression. That section is "Effects of Expansion and Contraction". It helps one to get your head around the concept. Once you understand the concept you can slowly expand your thinking as to what is needed on a large scale. Experimenting helps. Once you dive in to the real deal take small bites. You can easily get some pretty radical results that are tough to get undone."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:wanbryNever pass an opportunity to acquire or review a Lincoln Weld book.Thank Sandy for this specific reference.  This source affordsunderstanding from the top-down [result-backwards], before you begin.  Too often this forum addresses the 'what I did', and not the why; as a result, the done falls short.All of the Lincoln Welding references are written for comprehension andwell illustrated.Understand first, equip second, execute last; don't mix the order.Opus
Reply:Do a search on this forum on flame straightening....  lots of photos.   You might cinsider the amount of heat put into the material in order to shrink it.  Try to duplicate the amount of heat put in the weld with an equal amount of heat on the opposite side of the tube.   As mentioned it is best to heat to red quickly before the surrounding metal heats and expands.  It is prudent to take your time and do not use massive heats or you might shrink it too much.  In some situations firms will simply run weld beads on the outside of the tube to duplicate the welds used to make the Tee connection on the other side of the tube.
Reply:Originally Posted by hobohiltonSpray the water on one side of the tubing (The side you want to shrink).... Continue the process until the tube is straight.
Reply:Originally Posted by wanbryI have been searching online for books
Reply:BIG effing rose bud and the tanks to back it to start, then finesse, experience, and luck take over.Disclaimer; "I am just an a$$hole welder, don't take it personally ."