Bought 2 CO2 tanks today to go from fluxcore to MIG

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I bought my 110V fluxcore/MIG welder a little over a month ago. I've been looking to add shielding gas, since that seems to be common advice. My plan was to buy a tank of 25% CO2, 75% Argon. I'm just going to be doing stuff around the house, no immediate big-project plans or anything. So I was thinking about either a 60CF or 80CF tank (a bit more cost effective to fill than 40 CF, but still not as bulky, heavy, or expensive as something like a 125 CF). In watching Craigslist for used options, I saw someone selling a pair of CO2 tanks. Went to see them today, I believe they are both 20 lb tanks. One definitely is, the other is slightly (0.2") larger in diameter, and slightly shorter, but still 8" diameter, and 22.5" tall for the tank itself, 26" to the top of the valve. Both are steel. Both are past their hydrotest dates. That's unfortunate, but didn't surprise me. They were asking $30 each. Given that I need to have them tested, I offered $50 for both, and we had a deal  One tank is empty, but the other still has 20 lbs of CO2. I think I got a pretty decent deal, even with needing to get them tested (hopefully ~$20 each). So I am going to pick up a CGA-320 to CGA-580 adapter at my LWS, so I can use the CO2/Argon regulator that came with my welder. That will at least let me get started with gas. And the full tank should hold me for a while. After I use up the CO2 I could maybe consider looking into whether my LWS would let me trade a CO2 tank for an argon/CO2 tank. Or I can just stay with CO2. I don't expect to do be doing really-thin stuff (say, 20 gauge, 0.036", or thinner). So I'm hoping the extra heat of CO2 (vs C25) won't be too much of a problem. My current plans involve getting more practice, and doing some little repairs on my OPE. Beyond that, I need to figure out things I want to try and make.
Reply:Sounds to me like you did pretty good... and you know what needs to be done.Be prepared... when I switched from fluxcore to MIG, the thickness of material that I could weld with my 115 volt wire feed machine dropped a lot.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:The CO2 lasts alot longer than a similar tank of C25.  Some machines (like mine) are designed to run on pure CO2.  It's supposed to give more spatter than C25.  I bought an adapter to run pure CO2, then found a guy on CL this weekend who wanted to trade me a125 for a 30cu I had.  He had a small mig and needed something portable.  I got the 125 revalved, painted, pressure tested and filled for $75.  I think I did ok.You know you need to change your machine polarity for gas, right?TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:I am planning on changing the polarity, thanks for the reminder. I also have to swap to the other drive roller groove. Bought the valve adapter, along with a screw-on 1/2" flush-tip MIG nozzle, and some 0.023" contact tips. My Lincoln wire is 0.025"; the guy at Airgas told me they are really the same size, that I can use 0.025" wire with an 0.023" tip, that it's just a nomenclature thing. They said I could swap a 20lb CO2 tank for a 60CF argon mix tank, when I need to refill. So it's good to know that's an option. Though 20lbs of CO2 may last me a very long time  I am planning to start with the indicated flow settings on my CO2/Argon regulator, as at least a starting point. Maybe set it to 20 CF/hr and go from there. I know it won't be accurate, but it's something. I know I should expect more spatter with CO2 than with C25. But the price is right, and maybe I'll need the slight boost in penetration from CO2. I've heard CO2 spatter gets worse above 150A or so, not sure if that's true. My machine is only 140A, so I'm hoping it won't be too bad. I'm hoping for at least an improvement over flux core. Drf255, it sounds to me like you got a good deal! I was getting quoted prices of $200+ for an 80CF tank, so basically getting a 125 for $75, filled and tested, sounds great.
Reply:Make sure you use the Nylon washer on the CO2 Tank connection.1lb co2 = 8.74 of gas174.80 CF20lb tank is a great size, easy to carry for refills and workd pretty good, at least I liked it with my 135 I had.I still use it on my MM211Nice to have 2 tanks because you'll always run out when the LWS is closedEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Thank you for the info, guys, I appreciate it. Got home, swapped out to the solid wire, changed polarity & the drive roller. Hooked up the CGA-320 to 580 adapter, connected the tank. Installed the new contact tips, and the MIG nozzle. Then noticed that the contact tip was 0.120" back from the tip of the nozzle. I was expecting it to be flush. Checked the Radnor catalog I picked up this morning, I got nozzle 21-50. But I think I should have bought 21-50F, which is apparently the Flush version. I thought the one I bought was the flush one. That'll teach me  So, no welding for me tonight, will stop at Airgas again tomorrow. On the plus side, the 0.025" wire does appear to feed smoothly through the 0.023" tip, at least with everything cold.
Reply:You will get more penetration with the CO2 than the mix so it should help with the small machine. If you keep the tip closer to the metal you will hardly have any more spatter than the mix.