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Homeade bandmill trailer bowing after welding - HELP!

Started by Timberline, August 31, 2013, 06:31:24 PM

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Timberline

This morning I had a perfectly level bandmill trailer.  Now it is not  :o  I was ready for paint but it still  needed the angle iron rails that the carriage rides on.  When I welded the angle on, the track bowed up at the ends.




 



 

The affect this has is the two end bunks are 1/16" higher than the middle bunks.  The five middle bunks are surprisingly close to the same height. 



 

The frame is constructed of 2x6" 1/4" tube.  The angle iron rails I welded on are only 1-1/4", 1/4 thick.  I have 48 little 1 inch welds per rail.  I've never sawed a log, so will this be a problem?  If so, how do I fix it?  I am so bummed  :'(

js2743

can you get it back to level if you wind the middle jacks down first leaving the ones on the ends up?

Timberline

Good question.  I tried that and that's how it was when I took the picture.  For some reason it is so stiff it doesn't change it at all  :embarassed:

Fla._Deadheader


Was the tube perfectly straight before welding the angle on ??

IF you have a torch, you might jack up the middle of the trailer on both sides a bit more than you need to gain, and heat the angle for several inches. That will allow the weight to stretch that angle just a tad.

Be observant and measure many times as you go. Be sure both ends of the trailer are hanging unobstructed and maybe you need a bit of weight on each end.

OR cut all the beads and re do the welds being more observant. I know which way I would go.  ;D
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

Timberline

It was straight.  I don't have a torch, but I like that idea.  The only problem is I could see the angle pulling from the heat and cause the rail to be too low causing more problems.  So you think this is an unacceptable thing to leave as is?  I can't imagine cutting almost 100 welds and then redoing it.  I really don't see how I can avoid it happening again.  I am really shocked that it bowed up like it did.

Ianab

At a guess the welding has caused some shrinkage in the top of the beam, causing it to shrink slightly. It only takes a fraction of an inch to be noticeable over that length.

The mill will still cut, but it's going to follow that curved path. Means that the cant will have a 1/16 dip in it. When you turn the cant over, that's 1/8" difference. Not the end of the world maybe, but it's going to bug you.

Not sure how to fix it, short of finding someone with chassis straightening equipment. Then basically chain down the ends, big hydraulic jack in the middle, apply some heat, and carefully take the bend out.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

North River Energy

Maybe fully truss the underside of each rail with a heavy turnbuckle, chain or cable, and a spacer block set at the 'low' spot.

You can figure the required tension with a pair of ratcheting-type chain binders before you do a more permanent fix.




Or find a really large heat treating oven and torque plate...

GDinMaine

If you repeat the pattern of welds on the bottom of the beam it should pull it in the other direction.  I would start in the middle and work my way out towards the ends.  I'm guessing you would not have to weld the entire length.  may be half or 2/3.  That should give you a noticeable result. I'm no expert but I have done similarly not too elegant solution to a problem before.
It's the going that counts not the distance!

WM LT-40HD-D42

Compensation

Discouraging to see that with the money and time you have invested. If all else fails and if the remedy makes it worse or wavy there is always plan B, that would be a date with the grinder. If you think about it, that's two rails and your side angle. Don't worry you will get it fixed.
Is there any twist from corner to opposite corner?
D4D caterpillar, lt10 Woodmizer, 8x12 solar kiln, enough Stihl's to make my garages smell like their factory :) Ohh and built Ford tough baby!

beenthere

QuoteI am really shocked that it bowed up like it did.
A pretty common problem and nightmare when welding, so chalk it up as experience. Keeping the heat balanced on your main beams should have been your goal.
Possibly best bet would be to try to match the spots on the opposite side. Wish you luck.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

bandmiller2

There are two things I would try, the first is easy take it to an auto/truck body shop that straightens frames and ask them,possibly have them straighten it.Second I would find a piece of smaller thinner tube weld some on the top like you did on the trailer and see how it bends,then try welding on the bottom and see if it relaxes the bend.I would make  short welds perpendicular to the beam.This is where experience in welding comes into play,alas I'am no expert, you could ask someone that is. Frank C.
A man armed with common sense is packing a big piece

thecfarm

I'm no help.but just want you to know that I'm in your corner. Good luck to ya.  ;D It will all work out in the end. I do alot of things that causes me more work. I have to redo something because it did not come out the way I wanted it.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

pineywoods

Take it to a body shop that has frame straightening equip. They will chain the ends down to a big concrete block set in the floor and get under the sag spots with a big hydraulic jack. quick and easy fix. Either that or borrow a big heavy I beam, some chain and a big hydraulic jack and do it yourself. It can be done with just a torch, but that requires more than a little skill. Now you know why the bunks on most larger mills are adjustable.. ;D
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

Magicman

I know that it's easy to close the gate after the cow gets out, but your situation is probably why most sawmill manufacturers make the bed rails adjustable.

You probably would be dealing with too much height to add adjustable rails above what you have now?

Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

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SPIKER

Someone already suggested the easiest fix, is to flip it over and put very similar welds on the bottom starting in the middle and working your way out.   The next thing you could do is to use a laser and mark the top of the angle that is bowed and take off the outer ends with a cutter or grinder.    try to not put MORE heat in the top rail as that can cause more warping.   

Next time you should usually use light stitch welds only needed for the top angle and let them cool jump from side to side and end to end.   Welding heavy stitch welds or solid welds and or welding starting from one end to the other can cause this type of warping.
I'm looking for help all the shrinks have given up on me :o

Andy White

Timberline
You have already got the hardest part of this project completed! We had a similar problem on a set of homemade
bedways for a rotary broach. Try setting your mill level side to side and fore and aft, and use a builders level, or laser transit, and scribe the angle tracks level, and dress them to the line with a grinder. Work slowly to maintain accuracy, and you should be straight in no time. 1/16" should be a small amount of grinding. Otherwise, you may try heating the bottom of the tubes, and using water to "shrink" the tubes straight. Good Luck, and keep us updated on the fix.      Andy
Learning by day, aching by night, but loving every minute of it!! Running HM126 Woodland Mill, Stihl MS290, Homemade Log Arch, JD 5103/FEL and complete woodshop of American Delta tools.

drobertson

You can torch the bottom of the main beam, with a small red hot path, as said, from the middle working out. or run a small bead, I would torch it and let it sit, Keep a string in it and wait for the results, this is very fixable. The weld on top when cooling shrunk, this caused the pulling.   This is not hard, just a little time consuming, I would suggest to try and straighten it rather than running it.  The results will surprise you.   David
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

RayMO

You can also cut a narrow slot part way through the bottom of the tubing with a thin cut-off wheel and then pull the ends down to level and weld the cuts shut.
Father & Son Logging and sawing operation .

Timberline

Thanks for the encouragement everyone  :)  There is no twist from the opposite corners, thankfully.  Grinding down the angle really won't help things because the bunks then wouldn't be level to the rail. 

I think the two best options are having a body shop straighten it or weld or torch the bottom.  Weld or torch is probably what I am going to try since I really don't want to dump a lot of money into having someone do it.  As for bending it myself, I'm just not experienced with that sort of thing.  The only torch I have is the little coleman size type. 

Even though I hate to think of lots of weld beads underneath, it is probably the most viable option.  The trick is to getting it right.  I don't want to make it worse i.e. making it wavy.  GDinMaine mentioned starting in the middle, that's a good idea.  David, you said it was caused by it cooling.  I'm glad you mentioned that because have been thinking this whole time that the pulling happens immediately as it's welded.  Should I just wait until it's completely cool before attempting another weld?  I think I can do this but I am really nervous about messing it up more.   :-\

5quarter

here's  a thought...cut all but the welds at the ends. If your angle is in the "L" position, install set screws about every 18" and adjust the rails until they're level. then between the set screws, drill pilot holes and drive in self tapping machine screws. if your angle is in the "^" position, use aluminum shims to level the track about every 18" and secure by drilling pilots into the 2x6 perpendicular to the angle on each side and drive pan head machine screws using them as a clamp on the rail. You will also need to fab some adjustable rail caps, but those would come in handy even if you didn't have trouble with your frame.

   Glad you caught that now before you went any further. projects like this are always 2 steps forward, one step back. Its a depressing thought to have to undo your hard work. As Frank always says, make everything adjustable. I have been trying to learn that lesson myself for some time now. No truer words were ever spoken.  ;)
What is this leisure time of which you speak?
Blue Harbor Refinishing

drobertson

If it is welded, the stress is there, any heat at or on the current areas that have been welded will be mute.  I have successfully straighten 40' channel with a string and soap stone marking the points that need to be treated.  It takes a good day on a 40 foot beam.  Your time should be shorter. Just give the steel time to cool and react.  trust it and move down the section methodically.   A very thin red heat will do the trick, just give it time to work. think about it for a minute, a weld takes  a few seconds then the distortion occurs. It is cause by the  combination of the parent metal and weld contracting on cooling.  A acetylene torch will counter this, believe me.  Some may laugh, but it is a fact,  the only way to prevent this is preheating which only reduces the isolated effects of the weld area.   Give it a go, If I'm wrong then all you have lost is some oxy/acet  and the time spent. But it will work, trust it and be patient,    the only other comment I have is to get a center punch and peen the welds as they are, then heat the bottom of your main beam.   david   
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

YellowHammer

Bend it back.  I would rig a chain, full length under the rail, attached at either end of your frame and leave enough slack in it to place a small hydraulic bottle jack between the bottom of the rail and the chain in the middle of channel. It should look like a bow.  Then when the jack gets expanded, the rail will bow down. It won't take much to bend it and get it straight, and there should be little risk because you can take it slow and stop anytime
YH
YellowHammerisms:

Take steps to save steps.

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5quarter

Drobertson is right...I was having some cast iron Tig welded and while I was waiting, I was watching a couple guys welding a trailer frame. One guy was torching the outside of the frame while the other was laying down the welds to the inside. they seemed to move along pretty quick. when they had finished one side, the welder put a laser on the beam and the other guy would find a spot and heat it for a few moments, then move down the line and heat another spot. they had just started welding up the other side when my parts were done. Talk about attention to detail. I mentioned how impressed I was to the owner as I was paying him and he said that nothing walks out of his shop that ain't plumb, level and square.
What is this leisure time of which you speak?
Blue Harbor Refinishing

Brucer

On each stitch weld you got the metal hot enough to expand, but you got it so hot so quickly that the surrounding metal didn't have a chance to expand and the hot area lost its strength and the compressed metal flowed elsewhere (probably got thicker).

In other words, in tiny increments you got the top of the frame hot enough to expand but it wasn't able to.

When the whole thing cooled down (slowly), the metal recovered it's strength while it was shrinking and the top of the frame got a tiny bit shorter, one stitch weld at a time.

How to fix it? Several people have already suggested it. In short increments, get the bottom of the rail up to red heat very quickly and then let it cool slowly. Personally I use an oxygen torch with MAPP gas (no need for acetylene) and I usually heat up an area an inch or sowide running across the face, but not wrapping around the edges.. You could also run a bead in short increments down the bottom of the rail, more or less duplicating the pattern on the top (just as some people have said). I prefer the torch approach.

You might have to do this a couple of times. I usually spread out the "hot spots" on the bottom side and do the whole length of the beam. Then I check carefully to see how much the distortion has recovered and go back and do it in between the previous spots. Best to take your time and maybe not get it back in line the first time.

Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

kelLOGg

Timberline, I have been in your shoes! See https://forestryforum.com/board/index.php/topic,21082.msg300054.html#msg300054

I tried almost everything that has been suggested and only one worked: take it to a low end body shop! They will fix it in hours. It took me a year trying other approaches until someone on the FF made the suggestion and even though it took me a long time to find the body shop that would accept it, I was one happy camper at the end of that day. (If it had been a Lexus or Mercedes Benz it would have been quicker. "What kind of car did you say" was the response)

Keep the faith - you'll get it fixed. I learned a LOT about welding in the process. In welder jargon you welded on a non-neutral axis. It's easy to get caught doing that.
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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