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help! I warped my frame welding

Started by kelLOGg, September 06, 2006, 07:39:08 PM

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kelLOGg

I was welding a gusset to the underside of my rails which are 3 x 6 x 3/16  23 ft long and later noticed a bend at the weld site. The frame normally has a 1/2 inch crown. It is now about 3/4 inch which cannot be removed by jacking the end jacks. I cut the welds out with a torch at Cook's suggestion to relieve the "drawing" caused by the weld but it did not help. Before I try other approaches I want to ask if any of you have experience in correcting such blunders. >:( According to Cook I could have welded all day on the side of the rails but the bottom is a different story. My gallery pictures of the mill may help.
Thanks,
Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

VA-Sawyer

Run a bead on the top of the rail and 'draw' it back.  I have fixed many a weld problem that way.
VA-Sawyer

rebocardo

The only real way to get a bend out caused by heat, without wrinkles, is to reheat the metal and bend it back. This can take a bit of finesse because you might have to cut thin relief lines and then weld them over once you have a straight frame.

You probably do not have the skills (I don't) or tools (torch and rack) to do a proper job. Your best bet might be an old guy at a body shop.

Once the metal has cooled, cutting out a weld only makes a hole and weakens whatever it was cut out of.

The question is, what kind of metal (mild steel?) and do you have pictures? I guess it is some kind of sawmill track, one picture is worth 1,000 words though. Does the straightness of the frame effect the squareness of the cut or is it just so the head can move down the log?

The reason for suggesting a body shop is they usually have the racks and equipment for pulling and measuring and TIG welding.



4woody

I may be wrong  but i dont think 3\4 is much on 23 foot an with a good eye some chains & and string and a jack   you can fix it with out kinky it

4woody

i like 4 weeldrives have wrecked & fixed many like this dont try to get it all out in one place work  back in forth a little bit at a time

UNCLEBUCK

I know tack welding first will prevent alot .  When I practice welding aircraft tubing I can make the metal move alot. Completed airframes that have a bend or bow usually get straightened right out with heat from the torch . 3/16ths you might be there awhile .   When the shop in town removes cylinder sleeves they weld a bead down the sleeve wall every 90 degress and it just pops loose .  I would say va-sawyers is what I would probably do or else get a new piece and use this piece for other parts .
UNCLEBUCK    bridge burner/bridge mender

Sprucegum

Slow and easy now : let's take it one step at a time and fix this thing  :)

I am assuming your rail is a rectangular tube and you welded right on the bottom. When you did this you put a certain amount of heat into the steel in that spot. I won't go into detail about the expansion and contraction of the steel that went on there - unless you want it.

What you want to do now is cause the same amount of expansion and contraction on the top side of your tube.

You can do this with your torch and a little patience. Just heat the top, and a bit down each side, right above where you welded until you get it red, a nice cherry red.

NOW HERE'S THE TRICK!

Cool it quickly with a rag soaked in cold water. Get it right down to where you can put your bare hand on it then check the bow.

If its didn't move far enough back do it again.   

Good Luck

UNCLEBUCK

 When I straighten aircraft tubing with the torch I cool it slowly backing the torch off a little at a time so it wont shock the tubing and crack it and also makes it stronger . Probably different though for box pipe .  Amazing what heat can do isnt it
UNCLEBUCK    bridge burner/bridge mender

4woody

try the chains an jacks it worked trailers to for me

scsmith42

Bob, do you have a rosebud torch?  If so, heat your tubing up all around and very gently bend it back.  Since you still have to reweld the gussett, you might want to bend it more than needed, so that when the gussett is welded on you end up where you wanto to be.

Another option is to heat the tubing all around, and then cool the side opposite where the gussett is in order to shrink it more than the bottom.

One thing to keep in mind is that when you weld on one side of some tubing, the weld metal that you're adding is going in very hot.  When it cools, it contracts, and this is one of the things that contributes to the bend. 

If you want, you can run your mill by my farm (I'm about 30 minutes from Durham) and we can straighten it together. 

Regards,

Scott
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

kelLOGg

Hey, guys

Thanks for the responses. I wish I had a dig. camera to convey the problem quickly. The suggestions are all consistent with other advice I've gotten.
The bend may not amount to much over a 23 ft span but it all occurs between two bunks (where i was welding) so the lumber is shy by about 1/4 inch in that area. It is mild steel (1018).  Thanks to Scott for your offer. I'll be in touch.

Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

willknot

Hello Bob, did the same thing with mine , same size tubing exactly, It is a piece of cake to straighten with heat, one thing to remember when straigtening with heat it will get a lot worse before it gets better, What I mean by that is you will need to heat the high side therefore it expands causing the bend to get worse, but i guarantee you after it cools it will be a lot better. Heating steel and letting it cool shrinks the molecules tighter therefore pulling it shorter and thus straightening your rails.With a soapstone and square on the highside put 2 lines about 3" apart across the tube right beside your crosser, then on each 6" vertical in the centre of the 2 lines draw a " V " to the bottom on both the outside and inside of the rail. Now heat the area starting at the top 3" and work your way down both sides to a point on the bottom of the "V" until the top and both sides and top are cherry red and let cool on it's own. The reason you heat down the sides in a V  is you want it to shrink less as you get near the bottom. This minumizes wrinkling of the sides. Each area you heat can only be done once. If you find you like to go a little more in that area layout lines and do the same thing right next to it but i doubt you will have to.You will have no trouble getting your rails straight.Take the bull by the horns and do it.  :D Good luck

Willknot

kelLOGg

Willknot,
Your approach sounds good but I don't know the term "crosser". Is that a bunk? I welded the gussets on the underside of both rails so there are two on each about 10 inches apart and they are between bunks. I'm not clear just where you think the V patten should be.

Thanks
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

scsmith42

Bob,. I think that what Willknot is saying is if you imagined a wedge shaped cross section of your rectangular tubing, with the point of the wedge being on the center of the gussett and the wide portion of the wedge being on the opposite side of the tubing, by heating and shrinking all of the steel in the wedge you will offset the effect of the welding material that was added, and thus straighten the bend out after it cools.  Heating in a wedge pattern is important so as to minimizes additional stresses / warping as the tubing cools.

His philosophy is right on target.  I'm going to try to paste a sketch of the concept below.  Scott









Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

woodbowl

Before doing anything, consider this. I am concerned about the pressures of it's own weight and attitude that may influence the final shape after reheating.

Did you have it jacked up and level when the gussets were welded?

Was it sagging on the ends or just one end?

The larger Cook mills are welded with a "crown up" shape, as seen while resting on the wheels. At the job site, the back is jacked up first, then the front untill the frame is level. It uses it's own center weight to keep the end jacks in contact with the ground, rather than continuosly trying to redistribute settled jacks as on a flat rail system.

I'm not sure if your MP-32 has this feature or not.
Full time custom sawing at the customers site since 1995.  WoodMizer LT40 Super Hyd.

kelLOGg

Thanks for the clarifying drawing, Scott, that is what I thought Willknot meant. It makes sense to me. Woodbowl, I failed to level the mill when welding the gussets. The rear was hanging free with the sawhead on it. :-[I thought that was the source of the problem but Cook seemed the think it was welding on the BOTTOM of the rail that was the problem. If I back away and observe it in with the rear jack off the ground it seems that the rear is sagging. Before welding the mill had a 1/2 inch "crown up" shape which I jacked to flat as you described.
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

willknot

Helllo Bob, What I meant by crosser is bunks but I don't recommend trying to straighten it right at the bunk but right next to it, with your rails sitting with high side up the parallel lines should be across the top of the rect tubing, that is the 3" width and looking at it from the side the V should be drawn down vertical along the 6" width to a point on the bottom. It is next to impossible to try to straighten it right on the bunk so just go right beside it were it will pull without the stresses of the welds and you won't notice the difference if your right adjacent to the bunk it will be straight.I am talking one line of the 3" line flush with one egde of the bunk. Hope this helps.

Willknow

kelLOGg

Hey FFers remember this post?
It's been a long time since I updated you and that's because I had with some unsuccessful attempts at trying to correct some goofy welding. In the mean time I have concentrated on a dry kiln so now I'm back with good news  8). The mill is straight now thanks to a local auto body shop owner who was willing to work with me in straightening the frame. (Pure luck - I called all over for body shops but say "sawmill" and you hear "click" or "sorry it's not a Lexus" and he was only 6 miles from me!!). He has a frame machine which consists of steel plates in a poured concrete floor forming a network of anchor points. I backed my mill into his shop and he connected chains around the sawmill frame and attached them to the plates and applied force where needed via a pair of hydraulic rams. It took a bit of setting up but eventually we (he) got it done! It was far more force than I could generate at my place. And he did it w/o heat. Today I just sawed a 20 foot pine with no more than 1/16 inch variation over the length. I'm OK w/ that. Got photos but I can't upload them satisfactorly. Maybe later.

Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

scsmith42

Bob, I'm glad that things finally worked out.  I think that one of my neighbors knows that body shop and was working there when you brought your mill in!

Scott
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

fat olde elf

Hey Tarheel neighbor !! Glad you got your frame back in shape.  Hope you have as good results with your kiln efforts...Keep the Faith.......FOE aka Paul R.
Cook's MP-32 saw, MF-35, Several Husky Saws, Too Many Woodworking Tools, 4 PU's, Kind Wife.

kelLOGg

Scott,
That's right - I think his name was Mac. I asked him where he lives and it sounded awfully familiar so I asked if he knew you - sure 'nuff. Voila - small world.

Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

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