Welding Problem

[lawndoc]

I had my frame all welded and square until I welded on the axle mounts. The frame is now bowed in the middle about 3/4" up. I figure this came from the amount of heat in the steel when I welded on the axle mounts. I guess the frame is now scrap. Any suggestions on keeping the frame from bowing when welding these brackets on? Please help.

[D. Tillery]

What material did you use for the frame? You may be able to bend it back. That would be my first suggestion.

If you start over either weld a little then let it cool and weld some more. EG weld an inch on one mount, move to another weld an inch, move, let cool etc. But you would still probably get some warpage.

Or you can pre bend and clamp in the opposite direction, weld, let cool and release back to straight.

Or weld the bracket to a piece of plate then weld the plate to the frame. This can spread the heat but you should still weld a little at a time.

Hope that helps, D. Tillery

[lawndoc]

I used 2x2x1/8 tubing...

[David Grason]

I also really think you can bend it back. You haven't done the unforgivable here.

I'm also building my frame from 2x2x1/8. Mine is bowed slightly but not a whopping 3/4 inch up. I'm simply going to heat the entire length of the frame with the oxy/acetyline until I can coax it back. I've run into this before and it's a simple case of heating slowly and being patient. And I do mean PATIENT. This material is actually pretty forgiving. Before I panic, I'm going to flip the frame over and weld up the other side. I need to do 100% welds anyway. This will probably pull a lot of the distortion back out and then I'll only have a little to worry about. I have a heating attachment that replaces the cutting torch that throws a HUGE amount of heat. (Of course, it uses a lot of fuel, too.) Then I place the frame back into the jig and use a couple of come-alongs or weights while I slowly apply the heat. I'll let you know how it comes out.

In the future, I'm going to add more cross members to my jig and really clamp things down to avoid this. Also, I've already learned to weld just a little bit at a time. That's probably why my frame is not near as far out of alignment as 3/4 inch. I'd say that my frame is probably 1/8 of an inch. It's almost not even detectable but like I said, I've run into this problem before so I knew to be looking for it. I built a car carrier a couple of years ago and got a really noticable bow to it. But with the intended use that it would get, I just decided to live it on that trailer. It doesn't hurt anything. But with a project that starts out with metal working and then switches to wood working, I'd really like to have that frame is as darn near perfect as I can get it. Otherwise, I feel that this is the type of mistake that can amplify itself down the road. Lordy, I hope not!

With all the guys out there building their own frames, I'm really surprised that this hasn't been discussed earlier. You gotta know that others have run into this. So, did they just build their tears anyway and simply hide the distortion?

[David Grason]

Ok, I'm back. You're not going to believe this but I went straight out to the shop after the previous post and started heating the welded areas where I had mounted the axle brackets for the Dexter Torflex. I got 'em glowing red and the distortion popped right out. So I clamped them down and now that they've cooled, the frame rails are straight as an arrow. I only heated the axle bracket welds, though. I did NOT heat anything else. I figured that it was when I welded on the axle brackets that the distortion occured so I might as well start only with those and see.

Try this and tell us what you get.

[lawndoc]

Don't have access to a torch so I have clamped a piece of tube steel above the axle mount and straightened the frame, now I just have to figure out what to do next. I think while I have the frame straight I am going to weld in a piece of tube steel on the inside while I have it clamped and h0pefully the extra tube steel will hold the frame straight when I take the clamps off. Do you think this is a good idea. Also I took another measurement and I am only warped 3/8" and its right above the axle mounts. It just looks alot worse than it really is I guess. I think I'll try this before starting over and wasting $300 worth of steel and alot of work.

[ALAN GEDDES]

I managed to warp the current frame a little on the right rear. When bolting floor and cabin to it it pulled most of out. I can live with it now. Got to watch that heat when welding and I know better. Oh well !

[D. Tillery]

Lawndoc,
Adding a cross brace to hold it will probably bend the piece you anchor to and you will end up somewhere in between when you unclamp it.

I would not have really suggested heating it to bend it back into shape. Heating and bending tubing is tricky as it tends to collapse. I would bend it cold back into the shape you want. You can overbend it and when it springs back it will be in the right shape provided you bend it the right amount. Work with it until you get it right. Use some plates to spread out the bending force at your force points so you won't dent the tubing.

Useing a come along, like David said is a good idea. Even making a large "pipe bender" out of scrap and an old tire rim. Heck, back when I had less equipment (and less sense) I applied force with the weight of a vehicle to unwarp a piece of 1/2" plate. You still have alot of options before you start over.

D. Tillery

[lawndoc]

Well I ended up clamping a piece of tube steel to frame with a piece of pipe between tube steel and frame at the point of where frame was bowed up. With 2 heavy C-clamps I managed to get frame back straight. At this point I welded a 3 foot piece of 2x2x1/4" tube steel in the inside of the frame at the axle mounting bracket, using less heat and small welds. After taking the clamps off it was perfect. This site is great, if it was not for this discussion I would have probably scrapped the frame and built a new one and done the same thing again. Got to watch the heat from the welding. I think it will turn out ok. Next time I will make the outer frame work out of 2x2x1/4" tube and cut back on the heat and not burn in a 8" weld all at once.


thanks guys
scott