MIG welding gas pressure
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  1. #1
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    MIG welding gas pressure

    I'm a newbie and curious how to know when I need more or less pressure on my MIG welding setup. I have a Lincoln SP135 with regulator and argon75 tank welding on mild steel. So far so good it just seems like I'm going through the gas quickly...

  2. #2
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    Quote Originally Posted by spiwrx
    I'm a newbie and curious how to know when I need more or less pressure on my MIG welding setup. I have a Lincoln SP135 with regulator and argon75 tank welding on mild steel. So far so good it just seems like I'm going through the gas quickly...
    What are you running it at? You should have two guages, one for the tank pressure and another for the approximate flow. The flow should be in the 20 cubic feet per hour range down to as low as 15 CFH.

  3. #3
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    Good question, I was going to post same exact question. I get my mig on Thursday and I'd like to know as much info as well.

  4. #4
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    Do you have a flowmeter? Normally you control the volume flow, not the pressure. For a given setup, equipment, and environment you want a certain flow rate as indicated by a floating ball flowmeter. The pressure regulator acts to bring the high pressure in the cylinder down to a moderate pressure that the flowmeter is designed to handle, then you use the needle valve in the flowmeter to adjust the flow rate (in liters or cubic feet per hour) to the desired value based upon recommendations in books and from advisors to start with, then based upon your experience with your technique, equipment, and environment (i.e., indoors, outdoors, breeze, etc.). In the absence of a flowmeter, you have no idea how much gas you are supplying to the torch.

    awright

  5. #5
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    I just have the basic gauges that came with my welder, I'd assumed it was tank pressure and pressure at the gun it doesn't really say anything except a scale from 0 to about 35. So I guess thats considered the flow meter. I have been running at 20 and sometimes higher. I was just curious how low I could go to use as little gas as possible??? Do you know what signs I could expect to see in my beads or work from to little or to much gas???

  6. #6
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    one thing to look for is bubbles/air pockets in the bead. If you start seeing little pin holes, you need more gas.
    Smithboy...
    if it ain't broke, you ain't tryin'.

  7. #7
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    What you have is a low pressure guage calibrated in cubic ft. per hour. Since it is a pressure gauge the reading is really only an approximation of actual gas flow. I would try it around 15 and see if you weld are acceptable. Just keep lowering the reading until you start to get porosity and then crank in a couple of more cfh and you should be good to go. Just curious what size bottle are you using? One other thing is to check your fittings and make sure your not leaking gas. Also be sure to open the bottle valve all the way. Those high pressure valves seal only when fully open and fully closed. You also want to close the valve fully when you are not welding otherwise a small leak will drain your bottle.
    Dennis


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  8. #8
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    Spray soapy water on all your fittings. If you have a leak it will blow bubbles. Ought to have a dedicated spray bottle hanging close. Use it every time you change bottles.

  9. #9
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    Yup, ever since I was little fixing bike tires I've stored a spray bottle with water and soap

  10. #10
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    Spiwrx, what size is your gas cylinder? You may want to look into a gas saver product that goes inline between your argon outlet end of the hose and your welder. I believe Harris Calorific sells them to help you save on excessive use of gas.

    MJ

  11. #11
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    what gas regulators to use?

    Since we are all on the subject of regulators and such, I bought a used Lincoln Power Mig 255C and it has no gauges with it. I'm not sure what I need to get. I looked at the Lincoln adjustable gas regulator kit #K586-1 Would this do the trick or do I need a kit that has a flowmeter. It's all greek to me, as you know i'm new and green to all this. As always I sincerly appreciate all your help. Thanks!!!

  12. #12
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    It doesn't have to be a real flowmeter (the floating ball,) but those are nice, especially on bigger, nicer MIGs like yours. If you get one with a calibrated flowgauge, you might have to make sure that its stated orifice is the correct size for your machine.

    What gas do you plan on running through it?

  13. #13
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    Well not really knowing much about it since i am so green I was thinking about running Argon/CO2 75/25 mix. What do you think? Also I'm a DeWalt lover too!! My shop is all black and yellow. DeWalt RULES all others drule...hehehe Thanks MAC702 I appreciate the info...Oh almost forgot, if I decided to go with a calibrated flowgauge would you have any suggestions as to what brand or make to go with? I was looking at a Harris 355-2 flowmeter regulator but not knowing very much about all this stuff I wasn't sure if this is even what I would need. Again, I sincerly appreciate all the great info. Thanks sooooo much!!!
    Last edited by iroc; 04-30-2006 at 09:28 PM.

  14. #14
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    I really don't think it matters much. I have several cheap Smiths because they came will my Millers and my Hobart. I also have a little Italian one that also works well. A basic inexpensive one should give you trouble-free service.

    That's an ideal gas mix for doing short-circuit GMAW. Your machine is also capable of so much more.

    I have C-25, C-16, C-3, Argon, and 100% CO2 all available for my MIGs so that they can do pretty much anything.

    If you weld many things over 1/4" in-position, you'll love spray transfer with a higher argon mix like C-10 through C-2 or even a 98Ar/2O2

  15. #15
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    Most of my welding will be up to 1/8" for now until I get a feel for it. I will only be doing little stuff like mufflers, little things that break on riding mowers, things of that nature. The metal will be somewhat dirty and sometimes rust. Would you say the 75/25 mix with the FCAW process and .o30 Lincoln Innershield wire would do the trick? Man I have a lot to learn, but the nice thing is that I have an ace in the hole like you to keep me straight. Again I sincerly appreciate all your great help. Thanks!!!

  16. #16
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    Quote Originally Posted by iroc
    Would you say the 75/25 mix with the FCAW process and .o30 Lincoln Innershield wire would do the trick?
    Not both. For clean steel and welding indoors, just get solid .030" wire and the 75/25 mix (called C-25) and go GMAW. For dirty steel or outdoors (drafty) work, get some .030" or .035" Innershield and go FCAW.

  17. #17
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    OK thanks!!!! I was trying to practice some gas welding today and the barrel of my tourch got so hot within 5 min. I could not hold onto it any more. Does this mean I have a leak or maybe a bad o-ring? I don't know how it works but it never got hot like that before. Thank you for the help again.

  18. #18
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    Quote Originally Posted by iroc
    OK thanks!!!! I was trying to practice some gas welding today and the barrel of my tourch got so hot within 5 min. I could not hold onto it any more. Does this mean I have a leak or maybe a bad o-ring? I don't know how it works but it never got hot like that before. Thank you for the help again.
    Nah, the heat build up you're talking about isn't from leaks or bad o-rings. Leaks and/or bad o-rings would cause problems of a different kind.

    I would be curious tho, when you say the "barrel" was hot, you are talking about the short curved section between what I would call the trigger and handle and the nozzle (brass thingy). Or are you talking the actual nozzle itself. And of course when you say too hot to hold onto, you were talking bare handed right?

    Just a thought or two for general purposes, think of the whole dynamics of what's happening. Your are running the tip of your gun 1/2 an inch from molten metal for repeated short or even extended time periods. Molten metal. We cook hotdogs with much less than that.

    But if there is a practice here that could cook your gun we need to work on that, so let us know some more.

    I want to edit to add that it is possible to do some "cooking" of the backs of your fingers if you are not wearing a glove on you holding hand. More so with stick but possible with mig too. So we do need to hear some more about this.
    Last edited by Sandy; 05-02-2006 at 11:26 PM.

  19. #19
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    I was gas welding with oxygen & aceylene with a #6 and the barrel (the part you hold onto) became very hot within a few min. Usually it takes awhile before it gets hot enough where you can't hold onto it but now within a few min it's extreamly hot. Thanks for the help...

  20. #20
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    If i'm mig welding dirty steel (rust & scale) and I use FCAW and I use an innershield wire, do I use C-25 with that? Thanks again!!!

  21. #21
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    If that's a victor #6 , i'm thinkin that's a big (BIG) tip and it should put out a LOT of heat normally . i don't think i ever used any bigger than a victor #3 gas welding tip , -If we're on the same wavelength

  22. #22
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    DON"T use a wire feeder or "MIG" to weld dirty steel, yer askin for trouble , sorry . i think if you have to weld dirty stuff, bite the bullet &use 6010 5p (dc)But, i know that's NOT what you want to hear .

  23. #23
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    OK thank you for the info I appreciate it. Is 6010 a deep pentrating rod? Just was wondering because most of the things I will be welding are thin like 1/16" or 1/8" thats why I was considering mig. Remember I'm green to all this I am just learning. I really do appreciate your help. Thanks!!!
    Last edited by iroc; 05-05-2006 at 10:08 AM.

  24. #24
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    6010 would be one of the hardest sticks for that work, but still doable. 6013 (which I'm not a big fan of) of 7018 works better, IMO. Wirefeeders are better, GMAW best, but FCAW okay. FCAW if you can't get the steel clean.

  25. #25
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    Iroc : 6010 is about the deepest penetrating rod there is , by far (i am talking about stick rod) But I hate the stuff . It splatters like H*ll , throws dingle berries from here to eternity -it's used for roots in pipe welding ,sometimes the complete weld in pipe welding . It'll probably be here , untill judgement day, i think it's God's & Lincolns punishment for mankind

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