oil pan 4

iTrader: (1)

I have always had Argon around for stainless steel, titanium and aluminum welding and have always done my mild steel welding with flux core wire (using my 135amp Lincoln).

I got the chance to use a miller with C25 gas (75%Ar and 25% CO2) loaded with .025'' wire. It was pretty nice not having metal splattering every where.

Also I have read that stainless steel is best welded with a 3% CO2 to argon mix and that using pure argon is not ideal.
I have talked to a few people that run straight CO2 for mild steel, none could offer a better discription than "it works".

Wanting to try all this with out buying 4 gas bottles (pure Argon, C25, C3 for stainless, and straight CO2. I simply added a CO2 bottle and regulator then plumbed them together for use with my Argon.

As we all know the C25 mix is good for clean metal, great for over head welding. Very little splatter. And the welds just look really nice.

So far I have I mixed my own C25, (roughly 25% CO2, some where between 20% to 30% CO2) producing the same result as when I used store bought C25.

I tested and found pure CO2 works pretty good, a nice improvement from flux core wire. Works well over light rust, little bit of zinc galvanization, or small amounts of paint/primer that didn't get removed. Still a little messy and poppy sounding.
The main reason I tested pure CO2 is to see what happens in case I run out of argon.
It would be great for sticking 2 peices of steel together that you can't see and don't really care about.

After testing straight my C25 home brew I realized my argon bottle was running low.
I figured I would try higher C mixes since CO2 by volume costs a tiny fraction of the same volume of argon. So I tried a 50/50 mix of CO2 and argon and it seemed to produce welds as good as C25, tho the welding process its self was messier.
Slightly surprized by the result I figured I would try and add more CO2 to find the CO2/Argon limit for what I want out of my welder.

Turns out 5 parts C02 to 2 parts Argon seems to be about the limit of what I am looking for using .035'' solid wire. The welding process is poppy and does spatter almost as much as pure CO2 but the welds look very good, still almost as good as C25 with the added benifet of being able to clean the weld site better.
If I put down a bead using C25 next to a bead ran using C80 you would be surprized how little difference there is.
You would not want to over head weld with hi C mixes.

If you were so inclined you could rig a welder using 50/50 to a C70 mix and run a tall bottle of pure argon next to a 15 or 20 lb bottle of CO2 and run them for ever compaired to running and always running out of C25.
Or for a small scale welder a short bottle of argon next to a 20oz paint ball CO2 bottle could be a good pair.

I have not tried and I am not sure how I am going to mix up a 3% CO2 mix for stainless welding, but am sure I can figure it out.

I would like to add a new dimention to my on site gas mix welding with the addition of Helium, but my gas supplier never has any. Helium could take the place of adding a little CO2 for its "wetting" ability when welding stainless steel and aluminum. It may aid when welding titanium too.

Has any one else tried doing this?

lunati397

I just use 75 25 mix with .23 wire most I do is .25 inch steel and its welded that perfect

ive got a miller 211

oil pan 4

iTrader: (1)

Yes .023'' or .025'' wire with C25 would produce perfect welds. After I burn up this 2lb roll of solid .035'' wire I am switching to and staying with .025'' wire.
I should add everything I was welding was .150'' thick steel.
I plan on testing this set up on 1/4'' steel this week welding up some trailer hitch stuff. If solid wire and gas wont weld 1/4'' then I will have to switch back to flux core.

oil pan 4

iTrader: (1)

I finished off the .035'' wire.
I respooled the welder with .025'' wire and tried it out welding some 1/4 inch steel to some 3/16'' steel and it worked great with my little 135 amp welder.
Tried using pure Argon for a few inches of bead, it sucks, the weld bunches up and penetrates almost as if the polarity is backwards so I switched back to my 70% to 80% CO2 mix, there is so little difference between the 2 mixes I don't know why people spend so much money on C25.

oil pan 4

iTrader: (1)

I tested my setup mixing my own gas for stainless steel.
I run about 12l/min of argon and take my CO2 regulator that starts at 4l/min and open it up just enough to make the metering ball bounce on its base.
I get much better weld penatration than when I was using pure argon.

Using C70 to C80 mix for steel still works great.

oil pan 4

iTrader: (1)

I ran out of solid mild steel wire Saturday evening so I put in a spool of flux core, switched polarity and figured I would try something little different.
Since I had plenty of CO2 I tried running 4 to 5l/min of CO2 over the flux core.
I figured best way would be to do a CO2 off-on-off test and figured it would be no different one way or the other and I would just end up turning the gas off and leaving it off.
First test was to remind my self what a messy burn and fire hazard straight flux core wire was like.
Right away I noticed the flux core with a little bit of CO2 does not spatter as much and lays down nicer welds.
I turned off the gas and came back later and started welding again, right away I realized I think I like it better with gas on.
That little bit of CO2 also helps cool the tip and handle too.

I also tried welding aluminum last week with a little bit of CO2 mixed with the argon, don't bother, use pure argon or don't mess with aluminum.

myroc86

Interesting write up man, havent really put much thought into that since we dont have time to mix our own gases at work. I myself havent welded with helium mix gas but my boss has. I think the bottle we have in the rack is a 75/25 mix. You usually use it for a hotter weld to get better penetration. We dont use spool guns just TIG weld all our stuff, but you definitly need to use 100% argon for aluminum.


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oil pan 4

iTrader: (1)

Well I finely ran out of CO2 today, been using it since april, welded tons of stuff with it.
My single 15lb bottle of CO2 lasted through 2 or 3 short bottles of argon (40 cubic foot cylinders), burned up 4 or 5 pounds of solid core wire running a C50 to C70 mix most of the time, plus I burned up a pound of flux core running a little bit of CO2 coverage.
Also did a little pure CO2 solid wire welding, maybe 15 or 20 minutes total.

oil pan 4

iTrader: (1)

I think I found a solution to the problem of suddenly being out of CO2.
My CO2 bottle is attached to my welding cart with a clamp and hard lines, so I cant pick it up and shake it every day.
My CO2 regulator has a pressure gauge but it always displays the same pressure while the valve is open until there is no more liquid CO2 left.

I bought a liquid level indicator for a propane tank. Its pretty simple, just an indicator that you stick on the out side of the tank. If you haven't seen one before it shows the slight difference in temperature between the liquid and gas levels in the bottle, the liquid tends to be a little cooler especially when you are using it.