Mixing gases

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I have a question about mixing gases.  I've seen Jodi's video on mixing He and Ag.  I have a dual tank rack on my MM and a full Ag tank on my Synchrowave.  If I buy a full size 100% CO2 tank for my MM, I figured I could create 25/75 mix for steel and switch to pure Ag if I wanted to use the spool gun on aluminum.  Sadly, I'm questioning whether I will ever actually need my Synchro now that I have the MM and Spoolmatic.  So I guess I'd need two check valves and a Y fitting only?  Would I need to mix the gases at equal pressures or equal flow rates?TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Gas mixing is a bit more difficult than simply adding a Y valve and setting flow rates. It's possible to get a "mix" that way, but getting a consistant mix with a known content is not going to happen. Basically you end up with a "mystery mix". There's a reason why mixing setups are expensive. This subject has been covered several time here in the past. Several members here have them. Sundown being the one I can remember off the top of my head right now.As far as not needing your Syncrowave 250, don't sell it until you play some with the spoolgun. I started out doing alum with a spoolgun and quickly found it just couldn't do what I needed it to do and get the results I was looking for. After that I went out, bought a Syncro 200 ( would love to have the 250 for thicker alum) and took a class to learn tig. I found going around small round objects like  3/8" or 1/2" rods to be near imposible with a spoolgun. You simply can't change the gun angle fast enough as you go around the object. I guess with a positioner I could have made it work for some things, but not for everything I wanted to do. The spoolgun also has definate limits when you move to thinner alum or steel. You have much more control over the heat input than you do with mig. There's also a completely different look to alum with a spoolgun vs alum tig. Many people are willing to pay for that tig look on projects that show. I'm pretty sure that's why Denny uses tig for many of his alum diamond plate projects that could simply be done with his spoolgun. His clientel is very picky about apearances and want that look on projects that they purchase.Also add in there are any number of materials that you simply can't easily weld with mig for a number of reasons. Copper and Nibral comes to mind, not to mention, Ti, Mg and many others. If it's possible to weld them with mig, a roll of wire may be cost prohibitive simply because you don't need that much for a project. Stainless is another material that's often done with tig rather than mig. You can tig SS with the same equipment you do plain steel with ( 100% argon, same tungstens etc) where as you need trimix usually to do SS mig and often the SS is too thin for mig to be a good choice ( manifolds, exhaust systems etc). Picking up a small cylinder of trimix is possible, (I need to give my supplier a weeks notice so they can get on filled and sent out for me) but I'll pay almost as much as for a full 282cf cylinder and it's not cost effective for a small project. On the other hand I can pick up SS filler easily and if I set up a basic back gas or purge rig, ( here's where the Y comes in handy) I can do SS with my existing tig gear no problem.Granted for heavier materials I'd probably grab the mig most times, but if I'm doing thin material or need precision, tig wins hands down. ( sheetmetal body work being an exception where mig works better usually) If I had to do 40' of 1/8" alum on a dump body, I'd grab the spoolgun no question, but try and do something small and intricate with 1/8" and I'd grab the tig instead. Each machine has it's weak and strong points. A good welder knows when to use each to his advantage. It's why good shops usually have multiple machines as well as multiple processes.Last edited by DSW; 08-27-2011 at 09:00 AM..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Hey drf,Doug(DSW) has provided valuable info. for you to consider. There is a place for both MIG w/spoolgun, & TIG. I have both in my shop & use each for the associated jobs/projects I do weekly. As Doug mentioned, I use TIG for all the polished alum. d/plate classic/show car accessories & unique crafts I create. They are premium priced & the aesthetics must be "show" quality. The spoolgun MIG projects I do are mostly production runs that need to have a good profit margin & the ease/speed that the spoolgun provides. In addition, the spoolgun is definitely a value since the ease of changing wire grades/sizes can allow you to do different metals/thicknesses/conditions easily. I also have a spoolgun on my mobile unit & have had several outings that I used flux-core, 70S-6, & 5356 on different jobs on the same day. So, as you can see, it is very flexible.As far as gas mixing, you will not get optimum mixing without a gas mixer such as the Smith proportional mixer. You can find them on E-Bay or HGR Industrial Surplus quite reasonable. They make it a snap to adjust your gas mixes for any application.My suggestion is to KEEP BOTH MIG & TIG in your shop......each has their place & will allow you to profit for any job/project. Here's a couple pics of my Smith mixer.Denny Attached ImagesComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:I thought you had a mixer also Denny, but I couldn't remember for sure..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I have a question.Why not just fill a bottle of C25 for steel mig, and keep your bottle of Argon for spoolgun alum and tig?Last edited by shovelon; 08-27-2011 at 10:48 AM.Reason: spellinWeld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by shovelonI have a question.Why not just fill a bottle of C25 for steel mig, and keep your bottle of Argon for spoolgun alum and tig?
Reply:Originally Posted by shovelonI have a question.Why not just fill a bottle of C25 for steel mig, and keep your bottle of Argon for spoolgun alum and tig?
Reply:I have a mixer also..VERY handy!...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:If you are going to mix, consider a bottle of C25 and a bottle of Argon.  That way your mistery mix is always somewhere between 25% and 0%.  A bit less of a mistery.The Smith mixers are essentially a very big pressure regulator.  They guarantee that the two gases are preciserly the same pressure  ( I can tell you my Smith Mixer will maintain + or - .2 psi difference with no problem).   Beyond that, a y-valve could work.Note, argon and CO2 are very close in mass.  This helps issues.Also note, some MIG welders offer dual bottle racks.  Pretty sure Miller does for their bigger units.Finally note, keep the TIG.  Anything that require precision, good looks (without grinding), thin metals, or if I need to do something indoors, it gets done with TIG.  Even aluminum MIG has a 'spatter'.   MIG is like a hot glue gun, TIG more like soldering iron.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:Originally Posted by Drf255have a question about mixing gases. I've seen Jodi's video on mixing He and Ag.I have a dual tank rack on my MM and a full Ag tank on my Synchrowave.If I buy a full size 100% CO2 tank for my MM, I figured I could create 25/75 mix for steel and switch to pure Ag if I wanted to use the spool gun on aluminum.Sadly, I'm questioning whether I will ever actually need my Synchro now that I have the MM and Spoolmatic.So I guess I'd need two check valves and a Y fitting only? Would I need to mix the gases at equal pressures or equal flow rates?
Reply:If one is looking for the "cheapest" solution, then the recommendation for having a mig mix (C25) and a tig/alum mig bottle (100% Ar) makes the most sense.However, if you're looking for a spray mix or a pulsed spray mix, having a bottle of each starts to be more of an issue.If you're going to mix gases, get a MIXER.  The homebrew solutions (ie Y valve) are not accurate enough.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.