TIG with MIG welder?

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Is this a Project???  It may be for me, hopefully.  It may belong in the MIG TIG Stick forum, dunno, will leave it for the mods to decide.  I searched that forum for a couple hours, and didn't find anything relevant.  (There's too many processes there, too many threads.  Does that forum need to be split?)I have an HH140 HHot Glue Gun and an Airco PA-3A.  I do a lot of 14-16ga steel tube work and weld outside corners with overly large crappy beads that have to be ground off, even in the vertical down (?) position.  I generally use .030 Lincoln L56 wire, power 2 or 3, speed 35, C25 at 12-15CFH on the HH.  The Airco just blows holes in everything (even at a low setting, so I use it for 1/4"+ steel) - but would it be a better power source for TIG?What I would like to do is switch to (hopefully just plug in) a TIG torch with argon, autogenous, for outside corners, and sand them out to the same radius as the tube corners.  Before I go out and spend the money on an impossibility, I was wondering if any of you have had any success at hooking up an air (or is it argon?) cooled TIG torch to a CV source MIG welder and running outside corners with it?   Even as "scratch start" it would probably work.  I know, I know, TIG is CC and pedal - used a Miller AB/P 330 in 1989 - but I was wondering if a Jerry rigged torch on a MIG welder for a specific use like mild steel outside corners was even in the realm of possibility.  Pic#1 - MIG weld stick up about 1/8" or so, lots of grinding. That bead is bigger than it looks.   Lotsa grinding for six dozen of them!  Pic#2 - Got impatient.  Chop sawed 'em all off.Pic#3 - Turned up the heat to 4 and speed to 55 to burn a nicely radiused corner.  Pretty close to finish size, but I would have rather fused it with a tig to a smooth 3/16" radius without all the extra grinding! Thanks in advance for any help - you guys have been great!   Attached Images
Reply:Working on improving on your prep, joint type/fitup and MIG techniqueswill get you much farther, faster and cheaper than fumbling around with a TIGsetup on a MIG machine.Mitered joints shown on 2 x 2 x .095,  below have bevels ground on the outer tube faces.The outer edge is beveled as well, to allow for the weld bead to existafter flush grind/sand/radius. It appears that you may not be grinding any bevelsin the miter joint faces. Even if TIGGED, you'd still want to do bevels.The rough grinding, then flush sanding of the 2 outer faces and the outsidecorner takes all of 3-4 minutes.The outsides and ends of the prepped tubes have to be wiped clean, alongwith some wiping inside the tubes, to stop porosity, etc. Starts/stops seenwere to help prevent melt-thru. There was slight twist inherent in several tubes,visible by sanding mismatch, which the support post covers.These were frames cloned off the master framethen separated by 4 vertical posts; to create tables supporting flat print file cabinets.It was not a primo job, but utility...but they did get blasted & powder coated. (Witness one of the bleed holes on the tube framing inside.)[.023 ER70S6, Millermatic 211, Steelmix (84Ar/16 CO2) gas)http://weldingweb.com/attachment.php...1&d=1353218975http://weldingweb.com/attachment.php...1&d=1353218975http://weldingweb.com/attachment.php...1&d=1353219562 Attached ImagesBlackbird
Reply:Thank you Dave!   My problem is that I don't get enough "seat time" to get real good consistancy.  The joint shown was 2" sq tube .083 wall (14ga from IMS).  The chop cut showed at least half being penetrated all the way thru.  Even when I prepped (other) joints like you showed, the weld still stood proud of the faces of the tube.  Enough so that sanding would get a square corner without any weld profile (round-ness) showing.  Then I would sand to a radius and sometimes get a "joint line" letting me know that I had sanded right thru the weld.    This is an outside corner problem.  Inside corners and side faces are okay.  I was hoping to get a nice radius ready to sand from simply melting the corner.   I remember doing it with O/A in class back in '73.  Should I go back to that?The tubes were washed with simple green, welded on the patio with 12CFH C25, no issue with porosity, or anything other than BIG outside corners! At least with a bead that big I could sand them to a SHARP corner!  ... but I didn't - needed it to match tube radius. Attached Images
Reply:I'd definitely opt for .023 wire on tube that thin. Smaller wire will allow you to better fine tune your settings. I'd also agree that good prep like Dave suggested is the way to go. If you give the weld someplace to go, you won't get as high a bead, and you will eliminate the issue of sanding thru the weld.There is no substitute for seat time I'm afraid. Those joints are certainly doable with a bit of gap or a moderate bevel if you are skilled enough to keep from blowing holes in the material..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:No pro here, but 12 cfh on mig outside seems pretty low to me.  I'm generally at 20-25 with outside mig.   Maybe I'm using to high a rate?TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Originally Posted by DSW... If you give the weld someplace to go, you won't get as high a bead, and you will eliminate the issue of sanding thru the weld.There is no substitute for seat time I'm afraid. Those joints are certainly doable with a bit of gap or a moderate bevel if you are skilled enough to keep from blowing holes in the material.
Reply:Originally Posted by Fabn4FunThank you Dave!   My problem is that I don't get enough "seat time" to get real good consistancy.  The joint shown was 2" sq tube .083 wall (14ga from IMS).  The chop cut showed at least half being penetrated all the way thru.  Even when I prepped (other) joints like you showed, the weld still stood proud of the faces of the tube.  Enough so that sanding would get a square corner without any weld profile (round-ness) showing.  Then I would sand to a radius and sometimes get a "joint line" letting me know that I had sanded right thru the weld.    This is an outside corner problem.  Inside corners and side faces are okay.  I was hoping to get a nice radius ready to sand from simply melting the corner.   I remember doing it with O/A in class back in '73.  Should I go back to that?The tubes were washed with simple green, welded on the patio with 12CFH C25, no issue with porosity, or anything other than BIG outside corners! At least with a bead that big I could sand them to a SHARP corner!  ... but I didn't - needed it to match tube radius.
Reply:Dave, that's excellent advice.  I had thought about sticking the mitered tube end on the belt sander for a second and flattening it out to 90*, but then thought "why bother?"  But you've persuaded me - in the next batch I'll just have to "bite the bullet" and do it!  Even thought the sander time can be counted in seconds! And you're right about the idea of cutting square to length, then 45'ing the corner.  Love it, but ... that's an elegant solution that won't work when I cut 24 or (next) 48 mitered pieces out of a few sticks of tubing!  Easier to miter first, then chop or sand. My default corner radius is - of course - the "native" corner radius of the tube, so a three way corner is perfectly blended and looks like the tubes magically merge into each other.  Also, my default way to build tube structures is to grind out then sand out the welds to at least 220 grit so the weld is indistinguishable from the tube.  I REALLY LIKE that look.  I ALWAYS sand outside corners anyway.  Just can't leave them "raw". I don't want to go off topic with this (and I'll thread the full project next week) but my mig problem is beautifully expressed by this decorative tex star element - I ALWAYS seem to get sucked into grinding / sanding out everything!  Inside corners and out!    (need a growl smiley!)   And for this one, all I want is for those welds to look like Zap's or ZTfab's!   Then maybe I won't feel I have to sand it out!     Guess that was the idea behind this thread.  Interestingly, no one has stepped up and said "I hooked a tig torch to a mig and it worked!"   :  And here I thought it might be EASY!  Since I'm a stubborn ole' polack, I might just try it anyhow! Attached Images
Reply:Sorry not trying to thread jack, but what degrees are the angles in that star? I've wanted to make one of those for a while now, as you can tell why in my avatar.Northern Tool MIG/Flux coreWEL-BILT 4 1/2 angle grinderYou gotta start somewhere!
Reply:Originally Posted by dbalesSorry not trying to thread jack, but what degrees are the angles in that star? I've wanted to make one of those for a while now, as you can tell why in my avatar.
Reply:dbales - since I have to do it again a couple more times anyhow, pm me the height and I'll pm you back a pdf sketch.
Reply:A mig welder is constant voltageA stick or tig welder is constant amperageThere are machines that can do both but they are typically a larger machine using a wire feeder for example.Either find someone local to work you through your mig problems are practice some more, the screwing around trying a tig a corner is a waste of time when you could do it in a flash with the mig.I can see porosity in your weld and in this case your material is plenty clean so I believe you have one of two things causing this, either you need to turn up your shield gas/maybe your holding your nozzle too far away from the work OR you will find when you cap an enclosed tube, when you get close to being all welded up the hot air inside will push out through the molten metal = bubbles
Reply:Originally Posted by cd19... I can see porosity in your weld ...
Reply:Man did you do all that this weekend? You have been busy.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:Originally Posted by NoBigDeal FabMan did you do all that this weekend? You have been busy.
Reply:Too far, it's Scottsdale, I drive there 5 times a week. I even drive to apache junction on occasion, and I don't consider it far. Casa grande, or Prescott is far.........Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:Originally Posted by Fabn4FunInterestingly, no one has stepped up and said "I hooked a tig torch to a mig and it worked!"
Reply:Thank you Brad!  Figured there was a good reason.  You just saved me from doing the same thing.