Can I do a decent job welding alum with my MM175?

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I need your help. I bought a MM175 last year and with the help of a close friend who is an excellent welder I learned to weld. I now can lay down a fairly decent bead on a continuous basis.Now I have a need to do some alum welding. I know Tig would be the best way to go but what I need to know is will a spool gun setup on my MM give me decent welds? I've not seen any pics or heard much on the quality of a spool gun with a Mig machine like mine.My local welding supply advised me against even trying to push alum on my rig even with a new teflon liner without the gun.Most of the alum welding I would be doing would be .250 and smaller. This would be on my aluminum boat.I know nothing about Tig and it would be a learning process for me. For those of you who have welded alum with a spoolgun is it much more diffcult than welding steel?Costwise the spoolgun/Argon setup will cost me about half what a small Tig welder would. Should I bite the bullet and get the TIG or will the spoolgun do what I am wanting?Thanks for your help.
Reply:I sure hope someone answers this one. I bought a tig, but I am wondering how those spool guns work. I demo'd a push/pull cobramatic setup and that was sweet as pie. But still, not a spoolgun.Lincoln Power Mig 210MP MIGLincoln Power Mig 350MP - MIG and Push-PullLincoln TIG 300-300Lincoln Hobby-Weld 110v  Thanks JLAMESCK TIG TORCH, gas diffuser, pyrex cupThermal Dynamics Cutmaster 101My brain
Reply:I think the MM175 is spool gun ready.  If that's the case you would also need a controller.  Tig would be the best.  If you want to try a teflon liner in your 175 I don't see any reason not to go ahead.  The argon bottle will be needed for aluminum wether buy a spoolgun or a tig.DennisThermal Arc 185-TSWMillermatic Challenger 172VictorO/AAtlas Craftsman 12 by 24 LatheEsab PCM-875Wholesalem Tool Mill-Drill
Reply:I don't know about continuous, though.  You can probably lay a bead with just the welder and probably do a pretty nice one by mig standards, but you will probably be eating up a good bit of amperage.  The duty cycles on those 175 are not near continuous, and at the aluminum's amp requirements, you might just hit the duty cycle limits.  I have used both a spool gun and the regular mig gun...the spool gun is much better, but at a pretty big price.  If you are only doing this occasionally and not professionally (I am guessing based on the machine) you could probably get good/satisfactory results with just a Tef liner and U rollers...even better results with a shorter gun added into the picture...I have a 7-8 foot gun.  Some here have even used pvc pipes to keep their gun as straight as possible (a pretty good idea).  .035 wire is the minumum you will be able to push...and you WILL get birdnesting...it's just a matter of time and luck.  .045 would be better, but you might have to run the welder close to wide open to get it to lay a proper bead.  Also, 5xxx wire is stiffer than 4xxx.  In short, your feeder will work with aluminum, you just have a fairly narrow window of opportunity as to what you CAN do with it.  The spool gun just widens the window a little by allowing you to more easily use lighter gauge wire and softer alloys (without birdnesting) and as a result lower your amps.Smithboy...if it ain't broke, you ain't tryin'.
Reply:I have run several mig welders, and I believe firmly that the 175 WILL do a decent job on alum. with a spoolgun. My reasoning for the spoolgun, there is no amount of frustration you have ever dealt with like when the wire jams up and then snaps off, leaving the wire stuck in the liner when you need to get done.For spoolguns, I like the 5356 wire(stiffer), and I like the .035 vs. .045. You will get a smaller puddle, but better focus of the melting pool, thus better fusion in the long run. With a 175, you won't be doing any 3/8 aluminum, I can tell you that. But with proper preheat, you will be able to do some good welding. I ran another shops' 175 on 1/4 aluminum, and welding both sides, got good solid welds. With preheat, we did a bunch of 5/16 brackets 4" x 9". And they were good to go. As for duty cycle, you aren't doing full blown production, so don't worry about it. And there is no small, inexpensive tig welder that can do aluminum that I have ever heard of. If there were, it could not generate enough amps to do the job. The smallest one that will really do the job is like an econotig, or a dynasty 200. The econotig will not pour enough heat for thicker, or longer pieces, and the dynasty will cost you $3000. And it is really only good to say 1/4" alum.Last edited by Rojodiablo; 04-14-2006 at 09:15 PM.
Reply:But with proper preheat, you will be able to do some good welding. I ran another shops' 175 on 1/4 aluminum, and welding both sides, got good solid welds.
Reply:Originally Posted by SandyWhat kind of preheat temps are you talking about on let's say 1/4 inch and a 175?? For some strange reason I've never really wanted to get into the aluminum thing, just being nosy here.
Reply:Well, I can tell you it won't help you to try and preheat it until it's red hot!! About 450-550 degrees.
Reply:Originally Posted by SandyGotcha. Don't go for the red, just hot!!  Thanks.All in all it does sound pretty labor intensive. Also sounds like a dern nice boat.
Reply:The jester was to show I was joking.... aluminum NEVER gets red hot.
Reply:If anyone gets the chance, try running a shield gas mix of 75% Ar & 25% He vs straight Ar, you'll love it and probably won't go back to straight Ar.
Reply:Originally Posted by mjedudeIf anyone gets the chance, try running a shield gas mix of 75% Ar & 25% He vs straight Ar, you'll love it and probably won't go back to straight Ar.