Flux-cored To MIG Welder Conversion

[Rob] sent us some information on how he converted his flux-cored welder to a metal inert gas welder. He used a piece of DOM tubing as a collet with a side inlet tube that he uses to inject carbon dioxide. The gas is sourced from a 12 ounce paint ball CO2 tank and it looks like there’s a valve right at the junction with the collet. We wonder how long it would take to tear through one of those tanks, but if you’re not doing a lot of MIG welding this saves on the upfront cost of buying a separate setup.

32 thoughts on “Flux-cored To MIG Welder Conversion

  1. c02 as a shielding gas won’t give welds quite so pretty as using argon or argon/c02 mix. I really can’t imagine that tank would last too long.

    What I’m not clear on is if he’s still using the flux-core wire, making it a dual-shield machine, or if he’s using regular wire.

  2. The image of weld was a bit blurry, but it appears he’s still using the flux-core. He need’s to work on his trigger control though, that weld look’s pretty sloppy. Like it was choking and globbing up on the mating surface.

  3. It does seem a little weird.

    I’d imagine that if you need to do the seldom MIG/TIG weld, you’d just take it to a welding shop and have it done right.

    Anything that requires more than a little work should really use the right machine,such as a MIG welder.

  4. Sorry Rob, but that weld looks like what happens when I forget to turn on the shielding gas. I’m in no way a welder though, so keep trying.

    This is a neat idea. You might want to combine it with this though


    and weld off the beaten path with just a few batteries.

    As for the paintball tank, it can last a useful amount of time because the gas is stored as a liquid. What really empties a CO2 tank in a hurry though is using it to drive air tools.

    If you really want to get cheap CO2, the best way I’ve found is to buy used, expired CO2 fire extinguishers at auction or yard sales. Just make sure they’re still full and mount them sturdy upside down for gas. I’ve gotten an entire full CO2 tank and 15 lbs of CO2 for $15.

  5. Meh better go for the arduino duel core!

    The post mentions he uses flux-core and co2 together, i wonder if you could use an argon tank and regular mig wire.

    I might try this but i’d angle the inlet backwards to keep the hose out of the way. I bet you could wire an electric valve up and put a switch on the welding gun to help save gas.

  6. this is a cool proof of concept hack. im tempted to pick up a $90 flux welder from harbor freight and do the same thing, maybe with a better nozzle design and solenoid gas valve. (itd be really hard to weld in tight places with that piece sticking out)

    a comparable sized CO2 tank lasts a LOT longer than other welding gases such as argon because its stored as liquid. its cheaper to have refilled too.

    and not to nitpick, but i think he means COLLAR not COLLET. a collet is something else.

  7. Yep, its using flux core wire, i didnt have any regular mig wire avaliable at 3 am in the morn. The polarity also needs to be changed. Tonight im gunna make a nozzle on the lathe and really do it up right, with some steel brake hose to prevent the platic from getting too hot and melting. As for trigger control, its a bit hard when the welding trigger sticks lolz

    @ IsotopeJ: Precisley Couldnet have said it better myself

    Im thinking foot pedal or solenoid next

  8. @Rob Tonight im gunna make a nozzle on the lathe and really do it up right

    NICE! I was going to suggest using a lathe but didnt want to sound pretentious to those who dont have access to one. (i dont have access to one anymore) cant wait to see version 2

  9. Im not sure about this. I mean if you’re using a flux core welder theres a chance the particles are going to accelerate the particles past 88 mph making your welds go back or forward in time making the welder useless. I could be wrong though.

  10. @rob

    Is there any chance you might do a writeup of a comparison of your experiences with and without the c02 attachment? Might be nice to see something to help someone decide if this is worth their time to pursue.

  11. If someone is deciding between flux and MIG

    If you want to do sheet steel or thin tubing, you should go MIG with argon or argon/co2. 110v OK

    If you want to do up to 1/4 plate or a little bigger you can still go 110v but go with co2 as the shielding gas here will help the weld penetrate better. This is my main rig, a Lincoln 135 w/ mostly co2. but it does mix and fluxcore too.

    If you want to save money, flux seems to work out cheaper per inch of weld. With no shielding gas bottles, hydrotests, or tank rental fees, flux core is used in production welding whenever possible, even realizing that you’ll have to chip off the slag. You also can’t do the really thin stuff

    If you are learning to weld, get an auto-darkening helmet. They’re cheap nowadays and it will save you hours while picking up the needed base skills.

  12. Ok, looks like he’s running way too much gas, also, angling the barb on the colette back towards the handle, so the gas doesn’t spew straight onto the weld would be preferable. also, he’s using innershield, which is a gasless wire.

  13. Simple idea but there’s allot of work to do such as angling the gas flow out of the nozzle and through a diffuser and having a flow meter to get the right flow and linking it to the trigger so that it only comes on when your welding and having a post flow would help.

    If your not careful you could end up spending more than the cost of a miller xmt 350 set up that does mig tig and smaw so watch your budget and go with using materials that are free as much as possible.

  14. i repair welding equipment trust me flux cored wire sucks,if you want to convert a welder to gas then buy a gas torch and gas valve. but if you want to weld on the cheep then just use mma (stick welding).

    the gas will last about 10 mins if you remember to switch the gas off at the end of each weld.

  15. Well you cant weld much other then carbon with CO2 but would make an easy switch to helium (sell at walmart for balloons). Never tried it but you could actally mix the helium and CO2 and weld thicker joints. Helium helps heat input a ton.

  16. stainless fluxcore will run CO2. helium is used for aluminium, usually 10/90 helium/argon or 70/30 helium/argon. the more helium the hotter the weld, but definitely dont use helium on metal other than ali.Argon is another weld shielding gas that could be used for general work, mostly mixed with CO2 or for tig purposes it’s used pure. much more expensive though.

  17. Word of advise if you want Stainless to rust use Co2 unless your passivating the heck out of it. Co2 is not an inert gas and does cause rusting of stainless. Additionally Helium is used in much more then Al welding. Like I said it can be used on most anything to allow greater heat input. You are right it is used primarily for Aluminum as AL is has high heat dissipation so you need more heat input. But it is actually becoming used more and more in TRI-Gas mixtures with C02 and Argon as well to use on steel look up Praxair’s HeliStar® Blends.

    Sadly the only reason I know this is I have done R&D on many welding process and Qualified hundreds of procedure and 1000’s of welders.

  18. Should have just bought a MIG welder in the first place – you can use flux core wire with most of those, just turn off the gas.

    Also, you should be using a CO2/Argon mix – CO2 alone will comtaminate the welds.

    Using flux core wire with gas is just an expensive waste.

  19. this is an old subject. i just got through tearing my mig handle appart on mine model 61849 and it has the port to put a tube in the handle with a valve in the handle. it seems that with the new models it might not be such a hard conversion.

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