So how critical is a flat frame?

[Robbie]

Something evil this way lurks... on my trailer project! BAAAHHHHH! I was out in my garage last night standing at the rear of my newly fab'd trailer frame and as I looked to the front it looked like the front cross member was slightly bent at the ends. Hoping it was an illusion I grabbed a tape measure and a straight board and got to checking. Sure enough, each of the front corners are bent down about a 1/4"! I stewed over it for a while and realized it must have happened when my neighbor (the one who helped weld it) was welding the A-frame part of the tongue. We had the trailer upside down and as he welded it on the bottom he was kneeling on it and when the tube got hot it must have conformed to whatever dip was in his garage floor causing the bend.

What do I do now?!!?!?!?!?

Is my trailer no good now? I am worried that if I leave it how it is and bolt my cab down to it that the bend will cause stress on the cab and crack some joints loose. The cab is not skinned or sealed yet so I can still seal it fine I just don't want the floor to buckle and break loose or something?

Pics of the trailer can be seen in my build thread here:

http://tnttt.com/viewto ... &start=105

Any help, tips, advice is appreciated!!!

Robbie

[gregp136]

I am sure for many they would start over. Since I reuse a lot of stuff, I adapt. I would put a half inch shim between the trailer and the floor, and that would level it out.

Greg(and Laurie)

[Oldragbaggers]

Wow, that is such a beautiful trailer too. I agree with Greg, I would find a way to adjust it.

[Robbie]

I thought of setting the corners up on jack stands and reheating at the bend points and then standing on or hanging weight from the center to pull those corners up. But I guess I should just set the box on it first to see how "out of plane" it really is and if those are the only spots. Shimming isn't a bad idea. I think if I shim it I will just hang the aluminum sides down to the bottom of the frame to cover the gap and just use a bunch of roofing silicone in the gap.

[corncountry]

When you weld on only one side of thin material, such as sq. tubing, the weld will pull on the material making it warp. You could shim it or lay some more weld on the opposite side of the warped tube. It will probably pull back most of the way.

Jim

[Steve_Cox]

1/4" in the front corners isn't much to worry about. As you clamp, glue, and bolt the structure on, it will conform quite a bit. A quality construction adhesive/sealant will make small gaps disappear. With my teardrop I went through that angst and heated and tortured the frame into submission and got it within 1/10" in level, (while sitting on jack stands) Only to find lumber irregularities caused gaps greater than that at a couple of places during final assembly of the walls to the trailer. Bolts and construction adhesive made the gaps disappear.

[aggie79]

1/4" in the front corners isn't much to worry about. As you clamp, glue, and bolt the structure on, it will conform quite a bit. A quality construction adhesive/sealant will make small gaps disappear. With my teardrop I went through that angst and heated and tortured the frame into submission and got it within 1/10" in level, (while sitting on jack stands) Only to find lumber irregularities caused gaps greater than that at a couple of places during final assembly of the walls to the trailer. Bolts and construction adhesive made the gaps disappear.

Robbie,

I'm with Steve. I'm not sure that I would worry about 1/4" of bow.

I built my teardrop in the same manner as you constructing the teardrop shell first, then mounting it on the frame. When I picked up my frame from the welder, there was a 3/8" upward bow at the axle mounts. I used the brute force method - see picture below - to take out about 1/2 of the bow.



Before I set the teardrop on the frame, I applied window wrap to the frame. The wrap I used is that pliable, bitumen type membrane. The purpose of the wrap was to make up any gaps in the frame and to seal the deck screws I would be using to attach the shell to the frame. (I used the self-drilling, self-tapping deck screws at 6" o.c. into the frame rails.)



When I set my shell upon the frame, I supported the frame at the corners. As I started fastening the shell, it took out the remainder of the bow completely.

Take care,
Tom

[doug hodder]

Since I don't have a lay out table for welding, I have mine pull that much all the time when welding, no matter how careful I am on how I weld it up. Especially if you weld up spring hangers on the bottom side of the frame. I wouldn't sweat it.

Getting the frame square in the horizontal plane and squaring the axle to the hitch point is much more important, you can live with the 1/4". Others opinions may vary. Doug

[oregonguy]

about the only way I know of to avoid this outcome is to tack a large piece of plate steel to the opposite side of the material you'll be putting major welds into. You need to use a very substantial piece of plate steel so that it can resist the force of the warp that happens as the welded steel cools. The tack welds are strong enough to prevent the material warping away from the plate, and are easy enough to grind back down once the material has cooled off completely. Takes a lot more time to do it this way, but the results are nice.

Some guys will also let it warp, then go back and heat the other side with oxy/acetylene torch with a rosebud tip. This is tricky but, you can actually warp it the other way, back to straight, if you're careful...

Like everyone else says though, a minor warp isn't going to effect much if you know it's there and can work around it.

[Shadow Catcher]

1/4" is well with in what you can expect and trying to correct it probably not worth the effort. As a weld inspector of many years I would say live with it.

[Robbie]

Thanks for all the tips and reassurance everyone! My heart sunk when I noticed it like all that work and money was wasted. I am going to use the window flashing and some roofing adhesive when I set the box down for final fitment and just let the adhesive and flashing take up the gap and then bolt it down. I'm glad this seems like a common issue and can be worked around. Looks like I'm still on schedule for primer today!

[gww25]

As everybody has said 1/4-inch horizontal differences aren't to bad but if it was warped in one direction check to make sure that it's not also 'twisted' or 'torsioned' or even out of square as this can pose a problem with the axle and tracking once you get it on the road. I would triple-check every dimension and level in all three directions, X,Y,Z before you make a final decision on what to do and how to do it. Chances are that you won't have to do anything.

[bdosborn]

Getting the frame square in the horizontal plane and squaring the axle to the hitch point is much more important, you can live with the 1/4".

x2.

Who was that other guy who's frame was 1/4" out and he was all wound up about it? He took his trailer to the ITG and everyone that saw it (and knew him from the forum) would say - "Nice trailer but the frame is crooked".



Bruce

[Robbie]

Well I got the frame all primed up today and noticed the side rails where the hangers are welded are bowed a little too. I'm hoping since the frame is such thin gauge tubing that it will somewhat conform to the trailer box and get pulled straight when it's all bolted together. I guess we'll see!!

[len19070]

Warping while welding happens all the time and as others have said, 1/4" isn't too bad nor anything that can't be compensated for.

When I built a big frame for an "Over the wheel" build because of the method I was using I almost expected it.



I could see on the cross members more than 1/4" bow in 2' even before I started welding it.

To counteract this we clamped another piece of angle on top to keep it straight, then welded.





Happy Trails

Len