Oxygen in mig gas

[meadow street]

Any advantage in having 02 in mig gas?

I'm leaning toward 23 % co2 77% argon for mild steel but there is also an 18% co2, 2.75% O2, 79.25% argon one available.

Also an 18% co2 82% argon.

What do you use ?

[Vernonv]

Pretty sure oxygen is BAD (but happy to be corrected). EDIT : Did some reading and apparently it seems it is used (in low percentages) in some situations.

I use straight CO2.

[KBs PensNmore]

I use the 18% co2 mix. As a general rule (from what I've been told) the more co2 the thicker material being welded, hence pure co2 for structural work. To much o2 will give porosity etc, try welding wet metal!!!!!
Kryn

[rob streeper]

I use straight CO₂ for mild steel, works great and is cheaper than argon mixes. Read this for much more info: http://www.weldingtipsandtricks.com/

[WelderMick]

I believe the small O2 component (say in argosheild light) is meant to help with 'wetting in' the weld bead, so that there is a smooth transition between the base metal and the bead profile.
Cheers
- Mick

[Karl Robbers]

Plan on doing much spray transfer on heavy plate in the downhand position?
No? Then why pay a fortune for a gas that offers nothing much of benefit to you. Go straight CO2.
CO2 is better for dirty or galvanised materials, lasts longer and has a more stick weld like penetration profile. I truly believe that the whole Argoshield/Migshield industry benefits the retailers far more than the end user.
Argoshield has the advantage of spray tansfer capability. This however is really only of use on heavier sections in the downhand or HV fillet positions and cannot be performed overhead, horizontally or vertically.
I was dragged to the CO2 altar kicking and screaming over 20 years ago, now I rarely use much else for steel work and actually dislike using Argoshield gasses in most cases. If I am doing a heavy job, I put a roll of 1.2 or 1.6mm DW 100 or Smoothcore 711 fluxcore in which will outperform spray transfer any day of the week and is all positional into the bargain.

[rob streeper]

I'm still learning the subtleties of shielding gasses and after reading a lot of wisdoms on the correct gas mixes for various types of jobs I finally realized the obvious: Stop worrying about which gas mix to buy and buy a gas mixer.
I have a Lincoln multi-process machine and was looking for a way to avoid purchasing and finding a place to store half a dozen different tanks of gas. I finally woke up and went out and found a used Smith gas mixer on eBay for about $500, bought a tank of argon and one of CO₂ and now I can dial up any mix of the two that the welding guru's think that I need to use. I mostly weld mild steel and therefore I use about 10 tanks of CO₂ for every tank of argon.

[meadow street]

any special regulator requirements for co2?

flow rate same?

any issues with freezing?

like the idea!

sources of cheap cylinders anyone?

ps don't forget to remove your welding helmet when you walk down to the shops : )

[Karl Robbers]

CO2 cylinders use a different fitting. Three ways to go. Option A, buy a CO2 regulator. Option B, buy an adaptor that goes between your CO2 cylinder and your Argon regulator. Option C, change the fitting on your Argon regulator to the correct one for CO2.
People will tell you that you need a heater for CO2. You don't, I have never used one in 25 odd years of welding and while I have had plenty of ice form outside the regulator, it has never remotely looked like freezing up.
Flow rates of around 10 LPM will see you right for most conditions, Argon based mixes will run down to around 8LPM. While CO2 uses 25% more gas at first examination, it is a cheaper gas and there is more of it in the cylinder as well.
Some people buy beergas cylinders and use these as a cheaper option. Beergas is exactly the same as welding grade CO2, the only difference being that the cylinders are cleaned more carefully for food grade CO2.

[meadow street]

I'm so glad this forum has helpful members.

[RustyArc]

while I have had plenty of ice form outside the regulator, it has never remotely looked like freezing up.

I've used my relatively light inverter MIG machine with a beer gas cylinder hanging off it for a few on-site jobs where it's been a much nicer option than stick, such as overhead fillets to connect 40 SHS posts to the flat side of cattle rail, both thin-walled. I quickly discovered that if you had the cylinder lying flat, you were expanding liquid CO2 through the regulator and it got mighty icey very quickly. Leaning the bottle up so that it was gas going through the reg made for a much warmer regulator.

[Karl Robbers]

I quickly discovered that if you had the cylinder lying flat, you were expanding liquid CO2 through the regulator and it got mighty icey very quickly. Leaning the bottle up so that it was gas going through the reg made for a much warmer regulator.

That'll do it every time. Still a few people get caught with acetylene cylinders that have been lying down and not allowed to stand long enough before use.
Next time you have a barbeque and somebody just won't leave you alone while you are trying to cook, just "accidentally" tip the gas cylinder on its side. I guarantee they won't come near you again, even after the flames subside! The snags may end up a bit charred though.
Another memorable show was the day that a CO2 cylinder came off a truck in the middle of a roundabout, smashing the valve off in the process.
A white Christmas just didn't begin to describe the outcome.

[meadow street]

can't seem to find anyone who will supply the adaptor to go from the 801 Harris regulator to the co2 cylinder.

any leads?

i think I need a Teflon washer in there too somewhere?

regards

[Vernonv]

I had a link to one in this thread - https://www.woodworkforums.com/f160/welder-arrived-140039
but the link is broken. Best bet is to do a search for "Co2 to argon adapter" and see what you can find.

[Karl Robbers]

can't seem to find anyone who will supply the adaptor to go from the 801 Harris regulator to the co2 cylinder.

any leads?

i think I need a Teflon washer in there too somewhere?

regards

Weldmaster sell suitable adaptors. http://www.weldmaster.com.au/product...ries/y-pieces/
The sealing washer in the units that I have used are actually the good old fiber tap washers.