WHAT GAS TO USE WITH FLUX CORE WIRE

by me they recommend the tri mix. I have no luck with penetration with solid wire and tri mix so maybe they are wrong. I have tried 023 030 and it just sits on top of the panel. The .035 flux core works best. If I try to add tri mix to that the penetration goes away.

I know if you are doing aluminum you need pure argon, but I can definitely tell you I get no penetration with the tri mix. Just if that makes any sense to anyone.

Like Metalman said trimix (90% Helium, 7.5% Argon, 2.5% Co2- looking at the bottle of it I have) is used for Mig welding stainless. Used on anything else it is not the correct choice. Using it on steel it's going to weld very strangely, similar to what you said. For Mig welding mild steel 75% Argon 25% Co2 is what should be used. 85% Argon 15% Co2 can also be used on sheet. The lower amount of Co2 helps with less penetration but it is hard to find and really unnecessary as 75/25 works well with even the really thin gauges.(22-24ga)
100% Co2 will be a nightmare to use with thin gauge sheet because penetration achieved with Co2 is much greater than 75/25. 100%Co2 is best left to heavier material. The greater the amount of Co2 the amount of penetration will increase.
 
Tri-mix? I only used that once to MIG stainless sheet. What machine do you have? Did you try turning up the voltage? Even the smaller 120V machines should work fine on 18-20 gage steel or auto sheet metal without needing flux core. Flux core does give better penetration for an equal heat setting over solid wire and gas. Sounds to me you are not far off, maybe experiment on scrap metal to find what works. I've seen some machines work better with .023" wire and some like .030" on sheet metal. Does your machine have any charts with recommended setting? Some times that will get it close.

No, we have a Hobart 175, welded my waste treatment clarifier 1/4 thick no problems, 2x2 .250 wall for the rotiseree, welds where the stock glows on the 2 setting. Go to repair my boiler and its 4 and not even burning holes thru .125.

My son does most welding here, he is sold on the tig, but I am trying to make sure we still accept the fact the mig is a good gun for its purposes, like welding the front quarter thru the inner quarter or when you are dealing with a rusty frame. I just think getting this running like it should with solid will make it less of a pig welder.
 
I have looked inside the welder and there is no switch to reverse polarity, any help?
On the Hobart, there are two stud terminals. You need to follow back to where the ground cable bolts to, then see where the positive bolts to. That is what needs to be reversed.
 
If so follow the ground lead into the case and look for two terminals with wing nuts above drive roll and change it there. Electrode + ground - for reverse polarity
 
So do I switch the positive and negative wire connections around, Plus can you guys give me a setting for the guages? The lincoln is a sp 135T.
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My Father in law loaned me this welder and he had been using flux core wire, I was just wanting to be sure before I tore anything up.
 
There's a parameter chart on the door that can get you close on your settings. For the self shielded flux core your father in law uses, it's ment for straight polarity (Dcen). Switch the leads around and he will notice a smoother arc and less spatter!
 
Since this is your first time gas mig welding sheet metal, Might want to brush up on general how too knowledge. While mig welding can be quick for some things, the back & forth work of spotting in, grinding, planishing, & spotting in again isn't so quick.
You definitely need to do a sample weld on equivalent material at least 6 " long before proceeding. The neater you can weld it the less time you'll waste doing excessive grinding. If you knock down the excess height of your first skipped spot welds, then they won't act as heat sinks & cause you to do even taller tack welds to finish up. Look at your wire occasionally between tacks. If you keep ending up with a fat ball at the end of the wire, you will get a colder start each next tack. Snipping ball off wire each time if needed will help this. Wire brushing entire area between tacking sessions can be a big help also.
Mig welds will never be as pretty or as consistant as tig, but sometimes for some it can be a better choice. Lastly when final grinding I like to look at welds with a bright light on other side to look for missed gaps & put small red marker marks near gaps to highlight them before going back
 
Since this is your first time gas mig welding sheet metal, Might want to brush up on general how too knowledge. While mig welding can be quick for some things, the back & forth work of spotting in, grinding, planishing, & spotting in again isn't so quick.

i dont think this can be overoveremphasized. i was quite impatient when i was learning, which i highly suggest learning on some scrap- maybe find a scrap fender or hood to cut out and replace some steel on. i ended up with a mess and even more metal to replace because i was impatient.
take your time. do some welds, let it cool, and look at what the metal is doing. same way when grinding- dont let the metal get too hot.i use the back of my hand to judge- if i lay the back of my hand on an area im grinding and cuss words start flying i got it too hot.with some practice youll know when to let the metal cool down. the rolloc type discs on a die grinder are awesome for this.
i also have my air hose nearby to cool down the areas.
same with planishing- do some then look at what the metal is doing.
 
My Father in law loaned me this welder and he had been using flux core wire, I was just wanting to be sure before I tore anything up.

This is the whole deal, He has and you have been using flux core wire with the polarity for solid. Maybe you should just change the polarity and see a difference the flux core makes.

As far as welding sheet metal, for me its just tiny tacks all over. I pull the trigger til I see the metal glow, then move and pull the trigger when the glow is almost gone.
 
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