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Mower deck repair

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  • Mower deck repair

    A mower deck failed, as shown in the picture. I am a rather noob to arc welding, and would appreciate suggestions as to how to proceed with this repair. We are looking at the attach point for lifting the deck.

    Specifically, how much metal do I remove?

    What is the preferred process (MIG, TIG and stick)?

    I am inclined to remove a "v" and compress the lift point so that it is back closer to where it was before this failure. That would likely be something like a 2mm downward movement.

    Any other ideas or suggestions you might have. My take is that the complexity of this is moderate for my skills. I could be wrong.

    I believe the failure was aggravated by someone running the deck with the lift arms substantially off from being level.

  • #2
    if it's just the weld that gave out I would clean it up and use a mig to weld it back.if it's rusted through and through I would put a piece of aluminum as a backing plate and weld it with the mig. I do a few decks a year for people and they are amazed that I was able to repair them. the mig is the best way to go about this get some .023 wire and you'll be good from the decks I have repaird you'rs looks like it's in pretty good shape. if you need to add a piece of plate to lap over it lowes or tractor supply sells the plate in small pieces that way you don't have to go buy a whole sheet just for a little piece.


    • #3
      The local steel outfit sells steel with a minimum purchase of $25, at a low rate. So I can pick some up there. I need to get some to practice with.

      Thusfar I have only used 0.030, but I have 0.23 wire. I can do some practice welds with it first, if using 0.23 is recommended over 0.030.

      A question I have is whether the 0.023 wire will provide adequate penetration, as the deck is rather thick (three point hitch finish mower for tractors up to 60 hp).

      Thanks, tommy2069.


      • #4
        Do not use .023. This is a thick deck. Also the weld did not fail, rather the weld harden the steel around the weld and the vibration from the mower caused it to fail. Grind around the crack, reweld it, then flip the deck over and weld it from the inside. If there is room on the bottom(under the crack) weld a coulpe of strips perdicular centered across the crack. It is possible this is a flex point. Would have to see a bigger pic to be sure. If there is not room a couple small gussets will help.
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        • #5
          Just about any of those processes could be used to weld it, use whatever you have. If you have all of them then MIG would be the easiest and fastest. Unless it's extremely thin metal you should be able to MIG that with .023 or .030" wire (I've done body sheet metal and even welded coat hanger wire toghther with .030). TIG will work but it is a slow process with more precision then necessary and stick really really shines on thick base metals, much thicker than this would be, but both could be made to work.

          What does it look like from undernieth?

          I'm guessing that it actually rusted undernieth, got thin in that area and broke. If that's the case you'll likely be fighting a loosing battle with it till you clean all the rust away and replace whatever you need to replace before welding it. Either way you will probably need to find the ends of the crack and drill a hole through them to prevent it from cracking further, then welding it back together again.

          If it's not a rust problem, then that area was just designed with too much stress in that area and the weld and doubled up piece of steel was stiffer than the rest of the deck causing it to flex there and break (there could be other explinations like the weld HAZ was hardned by the weld and that cracked, but it really wouldn't make sense for the mower to be made of any more expensive alloy that would do that). If that's the case you'll be fixing it again unelss you make it stronger, you could likely make a doubler out of similar thickness steel and weld it undernieth and even weld through the crack into it to further reenforce it.

          If you want to fill holes using a backer (something that doesn't stick to the weld and lets you build up weld over the top of it), copper works better than aluminum. I typically use some copper flashing (used for roofs...) wrapped around a body dolly, to give it some mass, pressed up against the back of the weld.
          (aka: Silverback, WS6 TA, JYDog, 83 Crossfire TA, mpikas, mmp...)
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          • #6
            The bottom has less rust than the top. I believe the base metal failed from stress of someone improperly mounting the deck, and having asymmetric loads on the deck, with that side being lifted, and the other side being pushed downward. At least the damage is consistent with that theory.

            I can do any process, but I am better with MIG. I have a multimatic 200, and have been practicing with 0.030, C25.

            Other parts of the deck are thinner, due to water pooling, but that area has little rust, but top and bottom.


            • #7
              Guy that lives next to me finds old lawn mowers, fixes them and sells them for a living. Until about two months ago he was gas welding everything. Holy smokes. He finally let me teach him how to use his old thunderbolt, I gave him a tube of 3/32 6010, he was grinning from ear to ear by the end of the day. I showed him my wire feeders and he was wowed, but he wasn't gonna pop for the price tag on them. Of course I told him he was welcom to use my shop anytime he needed. He ended up trading with some feller, got a little 115volt flux core machine, now he's crazy happy and is welding everything he can find. Especially that pile of mower decks he's been sitting on. .030 flux core will probably be fine.

              Someone mentioned stop drilling the cracks ends, I think that's solid advice. A backer plate on the underside is also a sound plan. Don't over think. Sounds to me like you have a handle of what broke and why. With the expertise that these guys have given you and your own ability, I have no doubt you will have a successful repair.