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How to do you straighten AR400 steel?

Discussion in 'Truck & Equipment Repair' started by icudoucme, May 8, 2010.

  1. icudoucme

    icudoucme Senior Member
    Messages: 367

    I have a HLA/Hurst root grapple. it's made from AR400 steel about 1/2" thick tines. here is a link to there site. http://www.horstwelding.com/hla_items.php?id=112 . I've bent the tines pretty bad. The picture was taken after I straightened the tines as close as i could to straight. I then dropped them in the dirt and drove 10 feet pulled them up and had twisted metal again. I tried using a come-a-long and chains to straighten them that worked okay. I called HLA and asked if they had any tips they said "Call a local guy" I called a couple metal working shops and they all said the same thing. They can't weld ar400 and they don't want to try to work with it.

    I'm using the root rake as a root rake and to grab brush. Right now most of the brush and trees get stuck in the tines and I have to cut them out with a saw. (the tines have bent worse since the picture was taken I'll try to get an updated one)

    Here is what i have tried so far: Hydraulic spreaders, come-a-long and chains, and metal wedges bolted to a concrete slab (tried to "comb" them straight). I don't know if heating them up would be a good idea or not. Most metal workers I talked to said they wouldn't recommend it. My last option is to cut the ones that are bent like a pubes (curled back and twisted beyond hope) completely off. do you guys have any tips or helpful advice, besides buying a new one?

  2. JD Dave

    JD Dave PlowSite Fanatic
    Messages: 11,194

    Our stone fork is 400 steel also and we use heat to straighten, it may weaken it but not sure there is another choice.
    Last edited: May 8, 2010
  3. icudoucme

    icudoucme Senior Member
    Messages: 367

    Thanks for the quick reply JD Dave! Do you(or anyone else) use oxy/acetylene mix or straight acetylene. Do you cool it quickly with water or let it air cool?
  4. buckwheat_la

    buckwheat_la 2000 Club Member
    Messages: 2,254

    first off, if the welding shops in your town are wary of welding ar400, you need some better welders in town, lol. Not trying to be insulting it just that how do they figure that gets welded onto the frame work to begin with? So if this was in my shop and i we were doing the repair, we would be torching off those tines, using the 30ton press to straighten, and then re welding them on. to me that would be the best way to fix that. Heating those and trying to re straighten them is going to make it the weakest at the point where it gets the most abuse. Also if it were me, i would look at re designing those so they bolt on, that way in the future, when you have them bend as bad as some of those are bent, you can go to the local metal fab shop, and have them custom cut (preferably on a plasma table, or water jet) new tines for you that you can just bolt on with a high grade bolt. just my $0.02
  5. icudoucme

    icudoucme Senior Member
    Messages: 367

    That makes sense on cutting them off, straightening the tines, then welding them back on. I've never thought of re-designing it with bolt on tines. If it's cost productive I'll give it a shot on a couple of them.
  6. TonyG

    TonyG Junior Member
    Messages: 7

    I would cut them off,

    then replace. Heating will remove the temper, we heat AR to soften it for drilling holes into it. It drills like mild steel afterwords. We have used 7018 in different applications, however this is a very aggressive implement. Find a knowledgeable welder to reattach the new tines.
  7. JD Dave

    JD Dave PlowSite Fanatic
    Messages: 11,194

    I like the idea of making them bolt on but the plain fact is they aren't built heavy enough to begin with. You don't see rakes around here with bolt on teeth. The root rakes I've seen are 1" plate and built like tanks. How much was the rake if you don't mind me asking.
  8. icudoucme

    icudoucme Senior Member
    Messages: 367

    total price was $1289.62 it's a a small one 66" across with a single full length grapple. it's mounted on a JD 4520 utility tractor with a 400x loader.

    SNOWLORD Senior Member
    from MN
    Messages: 610

    Taking them off and straightening will work but they will keep bending they need to be twice as thick as they are, try to find a dozer root rake in the area and look at it to get some ideas. If there is a salvage yard with garbage trucks any where near you go there and buy some of the arms off the large garbage trucks that lift a dumpster in the front of the truck those are very good material and thick, we use those alot on heavy stuff.
  10. Wicked500R

    Wicked500R Senior Member
    Messages: 394

    Without knowing the dimensions.. This is what I would do if that was my tool. I would have that whole bottom half redone but I would have done so that it has a row of bucket teeth instead of those tines on the bottom. You get the picture ? Bucket teeth are replaceable and many different styles to choose from :mechanic: