beam help

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i have a W 10x30 beam(i think) i would like to cut it down to a 6" web.its gonna be about 70" long.should i take 4" out of the middle,or slice it and slide it together lettting the web overlap itself?if i slice it and overlap the web the flanges wont line up which im not concerned with.....but i am concerned about it being straight after welding.so...my question is do you think i can keep it straight?
Reply:I would think you will have a hard time keeping that straight.   How do you intend to cut it down ?  With a Torch ?  That will cause some distortion, then when you reweld it will probably distort even more.I dont really have a good answer on how to keep it straight.  Maybe you could cut it, weld it and flame straighten it later ?  I dunno im only a newbie apprentice comming up with ideas !
Reply:When you cut it, stagger the cuts so you dont get one area too hot all at once and also stitch cut, or do about 4" of cut and then leave a 1/4 inch un-cut. Let it cool all the way, then come back and nip the little stitches out. This should help...Maybe clamping some kind of a strongback to it would help also....
Reply:trade somebody for the size of I beam u want? If you over lap the two webs it would be faster and probbly keep it straighter, sounds stronger too. but as an extra caution to keep the 2 flanges paralell to eachother i would make some blocks the size of inside to inside of the flanges and clamp them on either side of the web, to keep the flange from pullin crooked, if that makes sence.Nothing Ever Got Done By Quitting, Never Give Up.
Reply:The cut will create more warp than the weld.   I'd follow TEK's advice .....  otherwise, just cut it,,,,  and pull and push as you are tacking up, to maintain the dimensions you want, as you are tacking up.  Clamping or tacking one side to a strongback isn't a bad idea, either.What's the application?
Reply:Originally Posted by mark8310The cut will create more warp than the weld.   I'd follow TEK's advice .....  otherwise, just cut it,,,,  and pull and push as you are tacking up, to maintain the dimensions you want, as you are tacking up.  Clamping or tacking one side to a strongback isn't a bad idea, either.What's the application?
Reply:when you weld it back together stich weld and jump fom side to side and short welds like 1 rod. Also try back welding so if your starting on the left side of the beam and overall moving to the right. then start lets say 12" inches to the right and weld to the left. then move down the beam to the right and start a new weld. but weld to the left. I call it back welding and it will control warping very much. also if your not in a hurry just weld a little and let it cool and then weld some more.
Reply:Could you use it as a "T" instead of "I" for your project?
Reply:Harry  -If I had logged in earlier and read your post before you cut it, I may have been able to save you some hassle.  The way that beam depth reduction is usually done in heavy temporary i.e. not pretty, construction is to first weld on two flat bars perpendicular to the web to become your new bottom flange, at the height on the web that you want to make the new bottom of your beam. This could also be done with back-to-back steel angles, with welds at the top of the vertical legs and at the heels of the angles. Then you cut off the remaining web and original flange. Maybe try it next time.Miller XMT304 w/22A Wire FeederLincoln Electric 3200HDHarris OxyAcetylene TorchesHyperTherm Powermax 45