Bending (mower) Blades

Discussion in 'Homesteading Questions' started by Non Sum, Dec 13, 2004.

  1. Non Sum

    Non Sum Active Member

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    I wondered if there is a tool (short of a large press), or combination of, to assist
    me in bending/straightening my lawn mower blades? I continually manage
    to hit roots and stumps with my lawn tractor's mow blades, badly twisting
    the oddly pre-configured blades. I generally resort to sledge and tree forks, but can never match the original configuration with such crude means. Any
    suggestions/products to help put things back in shape? Appreciate it!
     
  2. ed/IL

    ed/IL Well-Known Member

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    Perhaps you could raise the deck until you get stumps cleared. Make a small compost pile with a lot of manure on top of stumps and they will rot quickly. You could mark the stumps with something to help avoid them. For the blade you could make a jig out of a 2x4. Cut and grind to the shape of new blade. Repair damaged blade on anvil and check shape with 2x4 jig. Sharpen with file. Others will probably have better answers.
     

  3. Windy in Kansas

    Windy in Kansas In Remembrance

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    In my opinion a bent lawn mower blade should be taken out of service.

    A bent blade, even if straightened, will be out of balance. By using one you will cause undo strain on the quill/spindle or on the engine crankshaft on such mounted ones.

    I would suggest adding dirt around roots so that the mower goes over them, cut stumps down lower, etc. to avoid the problem of bent blades.

    A mower with out of balance blades is also very dangerous in my opinion.
     
  4. insanity

    insanity Well-Known Member

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    You must have one of the Huskys from TSC. :D Unless others have came up with that weird bend.I have came to the conclusion it is impossible to straighten them enough.They already look twisted and bent when new. :rolleyes: And its also very dangerous to hit with a sledge.They are so springy they go flying if you are not careful.(some heat would have helped) But I finally gave up.Replaced the blades.And dug up the tree roots with a pick.Well a couple where to big to fool with trying to dig up.A pick with the curved flat/hoe end is perfect for taking slices out of the top of them until there flush with the ground. ;)
    I also have one stump to dodge that i didn't feel like fooling with.I just marked it with dayglo orange paint. :D
     
  5. reluctantpatriot

    reluctantpatriot I am good without god.

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    Take those bent lawn mower blades, as you can't get them balanced again, and cut out two tanged knife blades. You will need a nice sharp hacksaw blade and file to do it, but you can salvage out two knife blades, more like brush knives depending on the blade size, that can be used even if not pefectly straight.

    I bend at least one blade a season on my pushmower, but since having sufficent goats and sheep now, the time I run the mower is very little. Little need to worry about stumps, roots and rocks.
     
  6. Non Sum

    Non Sum Active Member

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    Ed/IL, The stumps do get misplaced. I’ll try the paint idea. As for roots, they just jump up out of the ground somehow and grab ahold of the blade. I can’t figure out exactly how they do this, but they surely do it. Also, I pick up leaves with the mover this time of year. Deep leaves covering: stumps, roots, fences, and small children. The anvil/jig idea gets tough when you see just how thick this blade is. I tried pre-softening with a blow torch, but my patience ran out way before the gas did.

    Windy in KA, I know you’re right. In the best of all possible worlds, I should replace blades regularly. Unfortunately, I don’t appear to live in the best of all possible worlds, and I’m too cheap to shift worlds at this time. Isn’t “balance” a function of weight, and not shape?

    Insanity, (Nice name. Are we related?) I have a ‘MTD Yard Machine’ with 20hp of blade twisting torque. The new blades extend in planes ranging over several known and unknown physical dimensions. Why this is, and how much the grass is terrorized by this fact, I have no idea.
    I have a large, and rugged, yard. But, you and your pick are always welcome.

    ReluctantPatriot, I’m ‘reluctant coward’ to destroy otherwise serviceable blades. I do appear to get them back in the swing of things, with little noticeable vibration. I just wish to find a way to contort steel more efficiently.
    I was thinking the used blades would be more profitably turned into abstract sculpture if painted gold and mounted on a pedestal.
     
  7. reluctantpatriot

    reluctantpatriot I am good without god.

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    I have tried to straighten bent blades, but even when I got them back to what to my eye appeared to be straight, it was still enough out of balance that by the time it was spinning at air-cooled motor speeds, the vibration was horrible.

    I have limped through some mowing at close to idle speeds if I had to get something mowed, but as soon as I could afterwards I would buy a replacement blade. I just try to be more careful while mowing.
     
  8. insanity

    insanity Well-Known Member

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    :haha: terrorized grass. :haha:
    Yep mine is 21 horses of raw power to.Runs like a dream.Cuts like crap. :D It even has enough power to plow a garden spot when the center blade is bent into the ground. Makes a good detachting blade. :D

    You might try putting some blocks of wood between the blade ends and a truck bumper and a jack under the center of the blade.Adjust every thing out to push up at the bent spot.(hopeing yours doesnt have as much spring tention as mine,they would bend about 3 inches and when you release pressure spring right back to bent. :rolleyes: ) Ill give them credit these blades are stronger than any ive seen!
     
  9. rambler

    rambler Well-Known Member Supporter

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    A blade should be some form of spring or slightly hard steel. Bending and or heating makes this unsafe. Is the one you heated the one that keeps bending? You ruined the steel with the heat...

    Not real comfortable with the whole deal.

    Been around lawn mowers on our 4 acres of farm yard for several decades, and I've never seen a bent one. Sheared a couple of flywheel keys, and made a few sparks on big rocks, and wore a few blades down to something that didn't look safe.

    But, never bent one?

    Sounds like you need a tractor & brush hog to go over your terrain, they are built for this type of abuse. A finish mower is not, and you are going to hurt someone. JIMHO.

    --->Paul
     
  10. Old John

    Old John Well-Known Member Supporter

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    Hi Y'all,
    I have a friend that needed to clean out a brushy, tree-lined
    valley for horse pasture. He just rented a stumpgrinder, for half
    a day, or maybe a whole day. He said it was a great investment.
    It'd grind out stumps in a few minutes each. it made him work
    moving it around though.
    Of course, you'd have to get a rock-sled and clean up all your
    fieldstones & rocks too.
    Then, you'd have a much better pasture, with more room for grass
    to grow, hunnh.
    Just a thought. Cost you a few bucks but better'n killing yourself
    with a screwed-up mower-blade, hunnh.
    Have a good-un
     
  11. Non Sum

    Non Sum Active Member

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    Yep, rambler, they sure can, and do, bend. Insanity appears to have the same blade type. Bend the thick (c.3/8ths) sucker and you suddenly have a horizontal tilling machine/ditch digger.

    Good idea, Insanity, re: jacking up something heavy. No pickup, but 2 mobile homes. Course, it won't be easy trying to flatten the 3 or 4 angled surfaces, plus getting their respective angles back relative to each other. Do you think your tractor could take a simpler replacement blade? If/when I do replace I would love to get a flat blade; if there is such a thing. I see generic blades offered for hand-held power mowers.

    Old John, It's more roots than stumps, so a stump grinder would cure about 20% of the threat. No rocks here in E. TN. You're right, it may be dangerous or not. But, I take my operational code from your Nietzche quote, and grow 'stronger' every day.
     
  12. insanity

    insanity Well-Known Member

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    Nope they fixed it good.The blades have a star (looks kinda like torx bit) shaped hole where they bolt on.Never seen another like them anyway.But you can bet ill be looking. ;) Bet our mowers are made by the same company.i had heard mine was made by Murry.(after i bought it of coarse. :rolleyes: )I sure hope not. :D

    I hear ya on the angles. :D Wonder if you could cut into the blocks with a chain saw.Whittle off enough to get it to lay flat enough.Probably not huh.
     
  13. fordy

    fordy Well-Known Member

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    ...................I mow about 3.5 acres out of 5 here on little ranchito . Before I excavated all the subsurface rocks with a single point sticking up , what I finally did was buy some of those orange\red plastic flags on thin metal wires that they use to mark buried cables and such when the backhoe guy is digging another ditch close to buried cables . I just stuck them in the ground next to the rocks , in April when I started mowing and would mow around the hazard until I took my pick and dug up most of the rocks . An unbalanced blade , if run on a mower will do lots of damage to bearings and tension pulley's unless removed and rebalanced . ..fordy... :)
     
  14. Non Sum

    Non Sum Active Member

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    Insanity, I sure hope you're wrong about that 'Murray' rumour. Yes, I have the star pattern also. There was a MTD parts add at the top of the page that I just clicked on...$19.32 per blade. So, I just might try your idea of wood mold making. If I can manage fabricating it (big 'if' there), and if it works (another big 'if'), I will message you about it; I promise. I bend these damn things too often to be shelling out c.$30 (with postage) every time.

    Fordy, good idea with the little flags. Probably make my yard look like the United Nations on Flag Day.

    Forgive my density, but "balance" strikes me as a 'weight' issue; no? You're not the first to mention this threatened situation to man and machine, but I'm not getting it. Could you explain?

    My own thinking runs like this:
    I have a straightened paperclip here in front of me, balanced on an eraser. Notice how I curl up one end, and leave the other end straight. Voila! the wire still balances with the fulcrum remaining in the same position.
     
  15. fordy

    fordy Well-Known Member

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    ...........What , i do with my blade when I have it removed from the Mower , is take a round rod or wooden handle and Hang the blade on the handle by the large hole in the center and see if it is balanced . If one side is lower than the other I'll put the blade in the vice and remove a little metal with a grinder and hope it becomes back into balance . I wish I knew a more precise method that didn't require an expensive piece of instrumentation , fordy.. :)
     
  16. insanity

    insanity Well-Known Member

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    woaaaa! Go to TSC and see if your blades look like mine.Sounds like it.For my three blades for my 46inch deck (i think it is!) .It is 29 bucks.Or 18 each i think.But they didn't have my size in stock.

    Fordy is right on about the balance.I do mine like that to.They will destroy parts in the long run if not.Do it every time you resharpen. ;)
     
  17. rambler

    rambler Well-Known Member Supporter

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    Hummm. My paper clip fall off, or I need to readjust the fulcrum if I bend one side of the paperclip. The weight on the bent end moves in towards the center causing imbalance.

    Now, try spinning the paperclip a thousand rpm or so. Any tiny little imperfection becomes huge....

    Just bt bending the blade down, and then beating it back straight again you are stretching the metal, amking one side a different length & different mass than the other side.

    It creates imbalance.

    --->Paul
     
  18. Non Sum

    Non Sum Active Member

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    I check the balance on all my mower blades every time I remove them, and/or, file them. Honest. Bent, or straightened, the weight never changes. If it did, I would surely file it.

    I suspect rambler sneezed on his paperclip just at the crucial moment. The physics in my dimension say that weight is all of what makes the scales tilt. Be it a pound of feathers (or a pound of bent feathers) vs a pound of lead. You can rearrange those feathers all day, but they'll still be a balanced pound (unless you sneeze on them).

    Insanity, please give me a link/address if you have a picture of your blade. Mine (MTD) is a 42" deck.
     
  19. twstanley

    twstanley Well-Known Member

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    What I have done is put the blade in a large securely mounted vise and then heat the bent area with a torch for a couple minutes. Then use a pipe wrench and a 2 foot pipe on the end of the pipe wrench if needed and bend it back where you want it. Sometimes you need to bend it a couple times in more than one axis.

    I wouldn't worry about losing the temper or anything, mower blades are made out of mild steel so they won't shatter when hitting a rock or stump. Just let them cool naturally, don't dunk them in water as that might temper them a bit.

    As others have mentioned check the balance after you straighten them, I haven't found any that needed grinding the heavy end to balance after straightening, but it is a quick check.
     
  20. Non Sum

    Non Sum Active Member

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    I suspect it will take more than "a couple minutes" of torch time, but I'll sure give it a try. Thanks for clearing up the 'temper' and 'balance' issues. Mounting my vise on a buried post is the only way I can think of that will surfice for "secure."