warping

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other than tons of tacks on the joint, what are some other ways to help prevent warping?, i'm working on 1 1/2" x 1/8" sq tube on 45° corners, the length of the frame i am making keeps warping out of true..thanksStangnetShop Full Of Stuff. Joey
Reply:Joey, for starts I would clamp it down to a table.  Spread my welds out.  Kinda like how you are suppose to crisscross your lug nuts on your car, same basic idea, but with the welds.  In other words, do one weld, then go to another side of the part.  Weld one weld, go to another side.  Once all sides have been welded, go to the first side and make another weld on a differnt joint.  Continue as such.  Hope this helps.  Good luckCHRIS
Reply:And try not to get the joints to hot.
Reply:Originally Posted by TxRedneckJoey, for starts I would clamp it down to a table.  Spread my welds out.  Kinda like how you are suppose to crisscross your lug nuts on your car, same basic idea, but with the welds.  In other words, do one weld, then go to another side of the part.  Weld one weld, go to another side.  Once all sides have been welded, go to the first side and make another weld on a differnt joint.  Continue as such.  Hope this helps.  Good luckCHRIS
Reply:You should look at your framework carefully.  When you say it is warping is it going out of plane or is it developing a bow along its lontitudinal members?.  If your frame is flat like a garden gate the approach is different than say a conveyor gallery supporting conveyor rollers and belting.
Reply:If all you're doing is 1/2 inch and/or smaller tube then something like this works pretty darn good. If it is small tack it all up and check for sqaure, then start welding. http://www.northerntool.com/webapp/w...ssearch=153807For larger material the first thing on the list is to build a jig for holding things square. I've made a couple of fairly large ones that I can use on up to 3 1/2 inch tubing. Still tack, check for sqaure, weld, check for square, so-on. Plan on every large bead pulling so learn to counter that. Often even when clamped some large pieces will spring out of square when the jig is removed. You can generally get about 1/2 to 1/3rd of that back by welding on the opposite side, so work things that way.1/32nd at a joint equals quite a bit out of square at the end so you can sometimes start out of square planning on it pulling in or out. All that checking for square is a busy way of allowing for cooling time.
Reply:To add to that, most shops have tolerance specs.  Last shop I was in was 1/32" due to fact it was sawmill equipment.  Being machines makes a differnce.   Another shop I was in was 1/4" max tolerance.  But I had a policy of never being out more than an 1/8".  At 30 feet an 1/8 of an inch grows a lot.  At 100 it grows too much.  Anyways, Most other shops Ive been in was 1/16" tolerance.  Ive always thought that was pretty fair.  1/32" works, but 1/16" is a lot easier to see on a tape CHRIS
Reply:Keep in mind that your weld is going to draw or suck up.  This is going to be most defined at the last point of welding.So let's say you fit up a mitered ninety (two forty fives) like I think you're talking about.  When you're done welding the distortion is your legs have a bow in them towards the inside.You can mitigate some of this distortion by tacking up.  Then welding your inside vertical first and your outside last.You can take tack up two joints and weld one up welding the inside first versus welding it last.  The welded last one will have more bow or distortion than the welded first one.  This is because your last point of contact will be pulling out or in your earlier points of contact.You can correct the bow with some heat applied opposite of the bow.  You can use a torch or sometimes just laying down a tack and then burning it away with a grinder will work.  Keep in mind when you first apply the heat the bow will exaggerate.  It will get worse.  But as it cools it will suck back.You can see the effects of this distortion often in welded pipe fence sections.  It's faster and easier to sew a weld down than up.  So some people just rock doing vertical downs.  Then they look down their fence line and every panel will have sags.  It just looks unprofessional at best and really sloppy at worst.If they had ran their beads vertical ups the weld draw would counteract any effect of gravity over time and the panels would look like they were done in a shop with a jig.The sag can be corrected with heat once again, but why should it have to be done in the first place?life is good
Reply:Hmm,  dang it harv youre the first to have ever given me that advice.  Ive tried a number of differnt technicques too.  Always was under the impression that downhand put the least amount of heat compared to uphand, so I never even bothered with the uphand.  Will have to try that.  That really errks me lol.  Oh well, you live you learn.  Thanks for the good input there Harv.  CHRIS