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Bent fork on farm loader

Discussion in 'Forklifts/Telehandlers' started by Terryz, Nov 25, 2018.

  1. Terryz

    Terryz Well-Known Member

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    I have a fork off a Massey Ferguson farm loader. I t is tweaked about 1/2 to 5/8" 5" from fork upright. The fork measures 4 3/4" wide X 1 1/4" thick. Anyone have experience or luck in straightening forks.
     
  2. Queenslander

    Queenslander Senior Member

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    I’ve just chained them to the frame, applied heat with a rosebud and pushed down with the loader.
     
  3. oceanobob

    oceanobob Senior Member

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    Using techniques of flame straightening, where a narrow line of intense heat is added using a torch, will make short work. Small amount of restraint is helpful. Dont forget the hudson sprayer is part of the tooling and a rosebud is considered a bit to broad and wide of heat.-
     
  4. Queenslander

    Queenslander Senior Member

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    Bob, there is precious little technique in my method, just heaps of heat and brute force.
    After reading your post, I did a little googling and found it surprising that huge bridge beams could be straightened with nothing more than a cutting torch and a couple of porta power rams.
    I might start another thread in a day or two, after I get some photos of another straightening job I have, and ask your advice.
     
    DB2 likes this.
  5. oceanobob

    oceanobob Senior Member

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    I have always marveled at the idea of flame straightening, and studied the words carefully in the Lincoln Procedure Handbook of Arc Welding. Didnt really get the idea the torch must be intense and rosebud isnt the preference; but I am on to that idea at this point. All attempts that I have done always had a Hudson sprayer to cool er down to ambient, I think it is the differential heating that does the work. Some of my efforts have produced epic results, others so so. Tis all about where one heats it.
    I am now looking for a cutting torch big tip to match the max withdrawable rate of the acetylene bottle.
    Big force and lotta heat - we have all been there. Flame straightening is a sure different approach.
     
  6. hosspuller

    hosspuller Senior Member

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    Flame Straightening ?? Do tell … I have a bent fork too. Seems to be opened at the heel. (compared to other fork)
     
  7. Delmer

    Delmer Senior Member

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    Flame straightening is easier on something like an I or H beam, where you can heat up a small point on a relatively wide flange, then move to the next point. It's similar to heating up sheet metal body panels to shrink and straighten them. I'm not sure how you'd do it on a fork? They're a much more compact cross section, plus a harder grade of steel.

    I think I'd stick with Queenslander's method, chains, jacks and heat. The lincoln arc welding manual has some info on flame straightening, it's cheap from the lincoln foundation, or used.
    http://www.jflf.org/ProductDetails.asp?ProductCode=PH
     
  8. oceanobob

    oceanobob Senior Member

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    Most recent actual example coincidentally involves a bent fork.
    ~~~~~~~~~~~~
    Recently, a fellow used [abused] his accessory forks on his tracked skid steer and bent one of them down. In a panic and being frustrated with himself, he called me and I gave him by best guess and advice as how to proceed.

    He installed a small amount of restraint ( a loop of taught chain, I believe he mentioned that). Then he got his torch ready and his garden sprayer. He ran a narrow line of heat across the inner bend of the fork approximately where it seemed to be bent the most. Cooled it with the garden sprayer right after the heating step was completed. Before starting the next attempt, each time he made for absolute certainty the metal was quite cool (so he could easily lay his hand and feel no heat).
    Deadcold I believe this can be termed.

    This behavior was mentally accomplished by tending to his other unrelated chores.

    Over the course of the day, he did four "swipes" in the same general area, each time going a wee bit slower with the torch allowing the heat to penetrate a bit more, and as stated above, always assuring cooling prior to the next time. Each event corrected the bent fork, but the last one did a bit too much, prolly cause he was going too slow and allowing the heated area to be a little bit deeper. This is where experience is invaluable. LOL


    For the theorists on the forum....How do I explain how does this work to fix the bent part?

    As to the cooling.
    As far I as I can discern the forceful cooling is needed to remove the heat from the part asap once heating is completed to maintain the differential. Creating this differential is one of the actions that is doing the task at hand. Times I tried this with no garden sprayer did not work well at all or didn't work. I surmise one may use a garden hose, I propose the garden sprayer is less messy (no water puddles or mud to drag one's torch hoses or get one's boots wet or muddy....perhaps the garden sprayer was something they utilized in a shop environment as they didn't want another hose dragged around to be cut or ruined. Also from my experience, the amount of maintenance to keep a garden hose from leaking is another contributor to 'not generally advised or recommended'). Since I do concrete work I always have a garden sprayer or two or three laying around and most time the potable water is already in it.

    As to the heating.
    The theory of this flame straightening as best I can recite goes like this: the portion of the part, ie the metal being heated 'wants' to expand ... and it does do so permanently. This is due to this: the metal being heated the strength capacity becomes less and less....the behavior under heat is a rather rapid transition which is one reason structural steel must be fire protected. The movement to expand is resisted by the other portion of the metal that is not heated and remaining quite strong. One wins the battle. In effect that permanent change to the dimension of that portion of the steel is the key to this concept. In the example, the upper portion of the fork metal is being heated and it expands, yes indeed this makes an attempt to make the fork bend more [there are two topics: Restrained and UnRestrained flame straightening. If there is no Restraint, the item initially upon heating will indeed be looking worse, but once it cools it passes back by the point at which this was started. Been there and seen that; tis kind of wild really.] But the overall fork shape in this example of restrained bending will not be seen bending greater from an overall perspective because of the restraint (the loop of taught chain). But that particular exact section / portion that was heated will indeed yield, ergo permanently change its shape. In this case, once cooled it will be smaller than when it started as to the length and this will ultimately cause the fork to bend in the desired direction, resolving the overall deformity.

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Why do I fiddle and suggest this could be done with this so called Flame Straightening?
    Folklore & sage evaluation by proponents and/or investigators of this method indicates the metallurgy is not changed because of two reasons: one the metal is a type of metal that is able to be welded and withstand processes of fabrication, and two because the time at temperature isn't long enough to rearrange the crystal lattice. Next time I think about it, I will order some tempilsticks and try to add some metrics to what I am observing.

    Other reasons is: it is curiously attractive 'cause it takes some experience and some thinking to pull it off, but in many cases it is way easier than rigging or applying big forces and applying loads of heat....that event is what I call "hercules method" being done by me many times (as we all have done) in order to save or correct a piece. Please Note: there will most likely be an instructive mindful person who feels by either belief or learning or both this heating business is damaging the part :mad:....and if that is in the concern to the extent that prohibition of heating is held to high esteem, then that policy should be held true and complied with. I made this point, because like anything, it depends on the experience and judgement of the person doing the task.


    The best example (kind of lame) would be a nice straight piece of heavy wall shrink tube for electrical wire, if only a portion was heated and allowed to cool, the piece would be bent due to the differential in the lengths.

    Then there was the broken loader arm near the pivot on a Case 580K that was out in a field that I flame straightened just so perfectly that once the piece was welded up, the pin passed through both the bushings with ease. That job was my first time with this method and it was very sketchy and scary as my mind having only vague ideas and memories of assorted comments....and it was Unrestrained. Another story for another day.

    :cool: Emoji with burning (torch) shades and happy with the result. I should add, practicing with a scrap piece may be useful prior to making a mess out of something that cant be easily or inexpensively replaced.
     
  9. old-iron-habit

    old-iron-habit Senior Member

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    Back in the 70s on a power plant job in ND I watched 3 pipefitters align a 16" high pressure steam pipe using torches. It was probably a 1-1/2" away from good alignment at the weld joint. They started about 8 ft. away and using 2 big rosebuds and a monster torch tip they heated it on the side in the direction they wanted it to go. I though they were a** backwards for the expansion to move it. As I watched it moved farther out of alignment with the heat. To my amazement when they finished heating it they sat down, had a cup of coffee and in 15 minutes that pipe had cooled and contracted aligning it near perfect for a stress free joint. I was sure glad I had kept my mouth shut when they were heating it.
     
  10. oceanobob

    oceanobob Senior Member

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    Old Iron: that is a great example of what I term an 'unrestrained' bend and how it initially appears to be worse then as it cools it becomes better or in this situation 'near perfect'. I have done them in this manner without restraint and applied no additional cooling other than natural air movement.
    More recently I have made bends/straightening using the garden sprayer (reference that Lincoln Book in the link from Delmer in post #7 and titled in the post #5 above).
    *
    I should add, some attempts have been made where little or no movement has resulted. In each of those events, changing the location of the heating was the key.
    An example is a piece of channel in post 44 of post R & R Warehouse Floor in the Demolition Forum.
    Also there is a dock plate example in post 46.

    The channel became bent because of welding rebars to project from the inside face of the web. FYI Those rebars were welded by boring holes in the web and placing the dowel almost flush (+/-) and welding from both sides, exterior side protrusion [weld (puddle/fillet etc) and rebar tip] all ground flush. Weld shrink should have balanced but the actual reason for the double sided weld joint was to supply bracing to the crotch of the inside fillet weld. Trust me, these dock channels take a regular serving of abuse.

    There were a couple of these 'edge of dock channels', but the last one really didn't care to move by heating a pair of v's on the respective opposing flanges (three times done with minimal resultant accomplished). That idea of where to apply the heat on a channel (flanges) had worked in the past, but not the particular channel for that last leveler which is the one shown in the pics. Was it just a stubborn channel? LOL
    So, I continued to try to remove that bend by a different method by running a heat line all the way across the web on the side of the web opposite the dowels. It was quick, too easy, and it worked way better. Three lines about a foot or so apart done at three different times made the channel weldment as straight as could be.

    Sidebar comment and consequence of heating the flange 'attempts': as I recall there was a bit of an two or three places with an undesired somewhat pointed dog leg (or maybe kink is a better description) at the flange to web square corner as a result of that earlier method. This objectionable appearance was was removed & erased using a svelte grinder action to a scribed line [amount removed prolly no more than a strong 1/16th]. Because that square edge was the sight line for the Acceptance of The Work and the fitup point for the leveler, I wanted it to "look good". I mention it because this was an adverse result of a flame straightening effort - to point out it aint always roses, sometimes just thorns.

    Because the building owner saw the fix to that channel (previous time it was done on a weekend), received the instruction to fix the bent dock plate. One hat trick and one earns that task and sometimes even a title or a nickname, gotta love it. o_O