can i MIG weld 3/8 plate?

Discussion in 'Shop - Fabrication' started by glamiskid395, Aug 14, 2010.

  1. glamiskid395

    glamiskid395 Member

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    Moreno Valley, CA
    im going to be strengthening my radious arms by making the top and bottom plate out of 3/8" instead of 3/16" plate. (i got the idea from camburgs f-150 radious arm, or are those 5/16")
    will i be able to do this with a MIG welder? if so, how much do i need to turn the volts up? welder is a lincoln sp-200.
    would i need to do a double or tripple pass to have good penetration?

    thanks
    Mike
  2. philofab

    philofab Powered by Optima

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    Use the chart for your machine to see if it can do 3/8, if not do multiple passes.
  3. DBMETALWORX

    DBMETALWORX Well-Known Member

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    You will be maxed out with a 200 amp machine, so it's probably going to shut down after welding for a bit.. Don't turn off your welder when it does, let the fan run til it cools down & starts welding again.. Will possibly take a while depending on how much welding you need to do.. It will work though, not a good idea to do daily..
  4. atomicjoe23

    atomicjoe23 Well-Known Member

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    Yes, you will be maxing the welder out, but you can absolutely weld 3/8" plate with a MIG welder.

    I would suggest running two passes, a root pass and a cover pass. . .that way you aren't maxing the welder out and you won't have to wait after it shuts down on you, plus it will be easier to do two smaller passes than one big pass (unless it was a dual flux machine, then you can put some serious filler into a groove!!!).

    3/8" seems pretty thick to me. . .
  5. glamiskid395

    glamiskid395 Member

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    Would 5/16" be okay, the truck weighs a little over 5000lbs and I am running the c/o on the rad arm.
  6. atomicjoe23

    atomicjoe23 Well-Known Member

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    5/16" would be plenty!

    Seriously look at the metal plate that the pro builders are using. . .0.120-0.125" most of the time and if they need then they do a re-inforcement plate of 0.090"-0.095" plate for a total of between a 3/16" plate and a 1/4" plate. . .

    . . .3/8" plate is some serious stuff. . .good for winch plates etc.

    Even the HUGE plate bumpers you see are 3/16". . .the Bearcat's the Marines are crawling around in on base here for security use 3/8" plate for bumpers. . .but they are also having to rebuild the diesel engines at a ridiculous rate because of how much weight they are moving around at next to an idle nearly 24/7.
  7. glamiskid395

    glamiskid395 Member

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    The 3/16 I used just got bent like nothing, the pass side just had the shouck mounts that were 1/4" and that strengthened the top plate but not the bottom. The driver side had 1/8" side plates too and it was still bent some. I'll use 5/16" with 1/8" side plate gussets.

    Thanks guys.

    Keep everyone in your prayers tonight.
  8. philofab

    philofab Powered by Optima

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    Do you have some pictures of what and how it bent? It may be a design flaw rather than a material issue.
  9. 07FJRog

    07FJRog Well-Known Member

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    are you using mild plate, or chromo plate??????? sounds like mild to me
  10. Wild bill

    Wild bill Active Member

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    I would pre-heat anything over 1/4" thick even mild steel plate. It will weld much better. Definately two passes. Depending on the placement of the welds, v cut the edge with a grinder to get better penetration.
  11. glamiskid395

    glamiskid395 Member

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    the beams and radious arms are threats econo kit. im not sure what Dave at Threat uses, but the 5/16" im using know is mild im sure.
  12. atomicjoe23

    atomicjoe23 Well-Known Member

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    Agree with everything except pre-heating MS. . .definitely no need to pre-heat mild steel.

    I've welded MS 3/8"+ and had it destructively tested with no preheat and have NEVER had an issue. . .pre-heating MS never even came up once in weld school either. Curious as to why you think MS needs pre-heated???
  13. DBMETALWORX

    DBMETALWORX Well-Known Member

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    Preheating helps w/penetration when welding @ lower amperage ie: small machine. I only preheat alloy (chromoly) when it's thick .25 or more..
  14. atomicjoe23

    atomicjoe23 Well-Known Member

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    Ahhh. . .see now that I agree with, using a small machine beyond it's capabilities is definitely a time to pre-heat.

    Didn't think about that. . .just saw "pre-heat MS" and turned brain off.
  15. DBMETALWORX

    DBMETALWORX Well-Known Member

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    It happens lol..
  16. atomicjoe23

    atomicjoe23 Well-Known Member

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    Yeah. . .I usually try to be pretty open minded because I definitely don't know it all and am always looking to learn more!

    Thanks for the explanation and not feeling like I was saying you didn't know what you were talking about.
  17. glamiskid395

    glamiskid395 Member

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    Moreno Valley, CA
    Well I'll get the stuff welded this weekend, it's 5/16 so I don't think I should preheat but what temp do I get it to if I do preheat it?
  18. Wild bill

    Wild bill Active Member

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    Location:
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    Go to your weld shop and get a 350f temp pen. If you are not sure how to use it ask them.
  19. glamiskid395

    glamiskid395 Member

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    Location:
    Moreno Valley, CA
    well guys, heres how it came out, i turned up the heat on the welder but kept the wire speed the same, so i just went slower than i usually would. top and bottom plates are 5/16", shock tabs and 'moon' plates are 1/4"
    pics..
    [​IMG]
    [​IMG]
    [​IMG]

    and this is why i went to thicker plates, the 3/16" got bent,and broke a weld on the top plate from the coilover
    bottom
    [​IMG]
    top
    [​IMG]

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