Kayteg1 wrote:
Snip..
I am a welder when I need it and as I mentioned- probably the best fix is add welded plate on the side of I-beam.
Question is how to get the beam straight, or preferable bend other way for the time of the welding?
Will the center of the beam sag, when you jack up the ends?
In the past I was using 2x8 C-channels as ramps for equipment loading.
But one of those 10,000lb backhoes bend the chanel.
My reinforcement was adding welded rebar on the tips of C. But I did not have 10k press to straight it before reinforcement.
What I did was weld one end of the bar to the channel, than with torch warm up the bar in the range of 600F and then quickly weld the other end of the bar to the chanel.
Than I did 3" welds every foot.
Rebar when cooling down, shrank and pulled the chanel straight.
Obviously having trailer on the top of the chanel makes using torch a danger job, but similar effects can be done with cooling.
Hi Kayteg1,
I have the plan of a combo fix, partly bolt on, partly weld on that I feel good about and will work and fits my shop. Here is the quick word version, I sense you can follow it.
Yes, as you said, it will use 2 sister plates, one inside, one outside. To straighten the beam, support the frame from spreading, then at the bend area, stop drill a hole approx 1" down from the top flange. Saw the beam up from the bottom to the hole and jack the back of the camper up until the frame is straight and maybe a slight bit more for camber. Put the inside plate on, bolted in place on one side of the cut only at this point. Using E7018AC rod with this high strength steel, weld up the saw cut with the inside plate as a backing plate for a full penn weld. Grind and polish out the weld and bolt on the outside plate with the I beam sandwiched in the middle. Finish bolting the plates both sides of the saw cut frame together. The bottom flange needs gussets to stiffen up the lower flange and a bottom flange reinforcement that will weld on. I need to add the bottom flange reinforcements to the door side too to balance out the frame strength.
I want to see what Lippert can offer since Doug gave me a lead on them. I will post my method here in pic's/drawings shortly and the Lippert call may alter the plan, possibly even for them to do it if that makes good sense after I find out what they can offer.
To your question on, will the frame sag in the middle of jacking up the end? I know I can lift a good amount of the side of the camper when I lifted the end 3" to bring the bottom of the frame straight. 2,300# is on the force jack to get the 3". This 10" x 9 lb/ft beam is fairly rigid. I could see the tire contact patch almost go to zero from something like 6 to 7" when I reached the 3" lift point. That's why I know I have to chain the frame down if cold working this back into shape is attempted.
As far as did the beam bend in the middle, I would say, not much if any. I had a string pulled along the bottom of the frame from the front spring hanger to the end of the frame to declare straight. Once the bend area went totally straight, that was the 3" lift at the end and I stopped. There was no large visible by eye bend in the 8 1/2 ft from the bend area to the end of the frame. If I put an indicator on it, I might get something, but we are talking in the less then 1/64" range.
Your 8" C channel weld shrink fix method. Good deal and ingenious. :C Yes I know about weld shrink and it if for sure real. It can work for ya, or against. At work we where making many 21 foot long 5 1/2 ft cylinders welded up from 3/8" rolled plate with 3/4" ribs ribs every approx 3 feet to make the cylinder. Those 360 degree welds at the ribs, both sides no less, create a massive amount of shrink and warp. It was close to 4" of overall length weld shrink that we had to make the parts in each section a certain % longer to account for the shrink. The shop guys had to dial in the weld procedure dead on to keep the cylinder straight and repeatable from cylinder to cylinder. After experimenting, they got the overall length even parallel within 1/16 which was amazing. We also used vibratory weld conditioning (the Met-lax process) which really helped.
So yes, weld shrink is a powerful thing. There is science in it and art/skill that comes from doing a boat load of it. Eventually the shop guys can predict what that shape will move by what weld process. But they have done this for years learning that.
Here in my camper situation, this one is different. Or at least with what I have to work with. The camper is sitting on top of the frame and the thin I beam is fatigued already in the bend area. I know that I myself do not have enough experience to start putting weld beads on the upper flange to attempt to predict the amount of pull it will take to bring this frame back straight. And then all the heat at the Darco membrane and wood frame area is a concern. That and the added heavy compression stress from shrinking to an already fatigued frame rail is a concern. I'm suspecting, don't know, Lippert may present the weld shrink method but I'll know more after I call them. I don't know if that process can pull it that much to lift the back of the frame 3". Or if it can, do I really want to?
From researching this, Artic Fox uses weld bead in the upper flange area to create camber in the frame behind the axles when new. They use to weld approx 2 to 3" weld bead on the top flange at an angle as they showed in their 2007 camper brochures. My buddies 2 year old Fox, has the weld bead on the inside radius of the upper flange. He can't tell if the bead is on top or not as the camper is sitting on it. They may have changed their methods. On his camper, this is only in the axle area on the upper flange.
I'm assuming they are using that heat shrink to force the frame rail upper flange into compression. Since the upper flange is in compression, it can take more stress as the top flange is normally in tension overhung off the back of the axles. You have to pull all that compression stress to zero before the tension starts, thus creating more beam holding power. I do not know this for fact, but I can see the science adding it to that it will work like that. Point is, they do this all the time and have learned the technique. And the fact there is no camper on top of the frame.
Give me a day or 2 and I'll have my plan up to see.
Thanks
John
