mig vs tig for Aluminum

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I am a somewhat new hobbyist to welding and Have a small hobart 135 mig.  I am looking to weld aluminum and although I will not do much I would like it to be a fairly good looking job when I learn the technique.  Should I buy a tig or would going to a bigger MIg (which I could use anyway) and get a spool gun for the Aluminum work? I only see my doing Aluminum on the bench and not in any tight or awkward positions so I hope the size of the spool gun would not be a major drawback. I am looking forward to any help and advice I can get from the guys and girls on here that know more then I do, that would be everyone on here.If your answer is Tig. what machines would you recommend (200 to 250) amp either new or used? Thanks Ray Mc
Reply:You get the nicest look from tig on alum. I'd recomend tig if you wanted to do alum 1/8" and less. Mig is usually better with thicker alum, say 1/8" and up. That's not to say you can't do alum nicely with mig, just that tig usually makes a nicer bead. Mig alum is usually easier to learn however than tig. Learning to tig alum will take a lot of seat time to do it well. Don't expect to buy a tig and start alum and be doing projects by the end of a weekend. Expect to have to put in a ton of hours learning steel tig before moving on to learning alum. A good class would definately be in order if you were serious about getting up to speed on tig alum as fast as possible.As far as a machine, a 200 amp AC/DC tig machine will top out at about 3/16" on alum in reality. A 250 amp machine will get you to 1/4" with no problems. Smaller machines like Millers Diversion 165 and 180 will top out at roughly 1/16" and 3/32" respectively in real life.I went with a new Syncrowave 200 myself to do alum. It was a nice balance between functions and cost. The lower priced machines like the Diversions, you loose a lot of the advanced functions like AC balance, pulse and stick as well as being too low in amps from my perspective. The Dynasty 200dx would have been my 1st choice, but it cost 2x as much.On a buget, there are any number of nice used machines. I've seen some nice used Syncrowave 180's, 200's and 250's in the last year go for about 50-60% what new would be. You can get some real steals on old industrial machines like Miller 330A/BP's if you look around. They are big, heavy and need lots of power (60-100amp input usually). There are many other good used tigs as well often at a fraction of new.Last edited by DSW; 10-09-2010 at 09:32 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:Originally Posted by DSWAs far as a machine, a 200 amp AC/DC tig machine will top out at about 3/16" on alum in reality. A 250 amp machine will get you to 1/4" with no problems. Smaller machines like Millers Diversion 165 and 180 will top out at roughly 1/16" and 3/32" respectively in real life.
Reply:A serious aluminum mig machine will cost as much as an ac/dc tig.  The tig/stick machine, however, is useful for many other tasks than the aluminum mig can do.  If you already have a mig you're happy with for welding steel, I would go for the tig.  By 'serious aluminum mig', I'm talking about a 250 amp or larger machine, with either a push-pull gun (Python, XR, AlumaPro) or an industrial grade spool gun (Spoolmatic or Prince), not a little 180 amp portable mig with a tiny hobbyist grade spool gun.   Within the capability range of the small migs with light duty spool guns (under 3/16"), the tig is a MUCH better choice.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:DSW - Although I have yet to try out a Diversion, just from looking at the specs, I think 1/16"-3/32" aluminum is an underestimation of their capabilities.Since 70% of heating power travels in the direction of electron flow, the Diversion's 165 amps output in AC mode, (at factory set 72% DCEN balance), should have about equivalent aluminum puddle forming capabilities as a Syncrowave 180 SD, at 60% DCEN / "max penetration".And I figure a Diversion 180 (also at factory set 72% DCEN) would have approx. the same work heating power as a Syncrowave 200 DX at 60% DCEN / "max penetration".Also, I found that with welding aluminum, a little pre-heating with a cheap-o "bernz-o-matic" torch and a disposable air-propane bottle goes a looooong way.  For example, I tackled welding a ~5/16"+ thick, (and quite a large, substantial heat sink!) automotive aluminum roadwheel with my 200 amp inverter (which can muster 80% DCEN in AC mode) with just a little air propane torch pre-heat... like maybe 20 seconds.  Was prepared to run for a while with the pedal fully mashed, but I found myself almost right away puddling, throttling back and mooooving.Last edited by jakeru; 10-09-2010 at 03:18 PM.
Reply:Originally Posted by Rick VDSW, those are useful TIG numbers... can you provide something similar for MIG?
Reply:Thanks for all the good advice. I do want to do thinner aluminum eventually and with what you all shared It is clear I should go with a tig setup. There are no schoolds that I have found that will let me enroll to just learn the basics of say automotive tig and Mig welding they all want me to certify  which at 62 years old is not what I want to do. I will keep looking and being in Charlotte NC I think I could even find a fabricator that works or used to work for a NASCAR team looking to pick up some side money to teach me the basics. And if all else fails I can watch videos and go out in the shop and melt metal until I figure it out.Ray
Reply:Originally Posted by jakeruDSW - Although I have yet to try out a Diversion, just from looking at the specs, I think 1/16"-3/32" aluminum is an underestimation of their capabilities.Since 70% of heating power travels in the direction of electron flow, the Diversion's 165 amps output in AC mode, (at factory set 72% DCEN balance), should have about equivalent aluminum puddle forming capabilities as a Syncrowave 180 SD, at 60% DCEN / "max penetration".And I figure a Diversion 180 (also at factory set 72% DCEN) would have approx. the same work heating power as a Syncrowave 200 DX at 60% DCEN / "max penetration".Also, I found that with welding aluminum, a little pre-heating with a cheap-o "bernz-o-matic" torch and a disposable air-propane bottle goes a looooong way.  For example, I tackled welding a ~5/16"+ thick, (and quite a large, substantial heat sink!) automotive aluminum roadwheel with my 200 amp inverter (which can muster 80% DCEN in AC mode) with just a little air propane torch pre-heat... like maybe 20 seconds.  Was prepared to run for a while with the pedal fully mashed, but I found myself almost right away puddling, throttling back and mooooving.
Reply:Ray,  Try taking a course at CPCC.  I just picked up a Miller Econotig and being an employee at UNCC I had the welding instructor give me some 1/2 hr lessons over lunch.  My son took the basic course at CPCC and really learned a lot about stick and mig. My Econotig handles 1/4 in fine and I'm learning how to do some thin stuff now (1/16 in).Dr. Bill
Reply:Inverters simply weld thicker metal than their equally rated tranformer machines. (tig welders)Also inverters form a puddle much faster which is one reason why they do this.Inverters tend to make the puddle from the center out while tranformers work from the center in.A Dynasty 200 will weld a good bit hotter than a Syncrowave 200 as far as thickness ability goes.If you are welding on large massed complicated joint weldments, that are multiple layers thick of 3/16th's you will be at the top of a Dynasty 200's threshhold....otherwise if you are just welding weldments of medium sizes and mass, with proper joint prep you can weld 1/2" thick jobs all day long. (by welding on both sides)  I use one everyday both with customer's power and from my Bobcat.I could see where this information would seem a bit exagerated to someone with a transformer machine, BUT, once you become accustomed to using an inverter machine and then use an equally rated transformer machine, you will immediatly notice the shorcomings of the transformer if you are pretty sharp.On the professional Miller machines the migs are rated on a fillet weld on a "T" joint. If you set a 350P up like the chart says on just a normal butt joint I feel it is quite a bit too hot for my ability.I cannot speak for the little migs on aluminum. With the need to use spray the window of ability is so small with these machine you have vitually no duty cycle at all. I repair a good bit of poorly welded things that have been done by people with small mig machines. The welds are normally way too cold IMO.....YMMVMiller Dynasty 700Miller 350P with Aluma-pro push-pullMiller 280 Dynasty with expansion card Dynasty 200 DXMigMax 215 Enuff power and hand tools to create one of anything..... but mass produce nothing!!!
Reply:I agree with Fusion King about inverter tigs having good output for thicker aluminum.  I have welded 1/2" and even 3/4" aluminum with my little TA185.  It required beveling, multiple passes, and alot of time heating it up first, but it does weld that thick.  I normally use it for 1/4" and under.  I would very much like to have a TA300 for the thicker aluminum jobs that I don't want to mig.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Yes there are many times a single pass is just out of the question.Maybe in production where things have been worked out completely.Altho I am not saying to weld heavy equipment with a 135 mig either.You gotta use yer head.If I was only allowed to own 1 welder it would be a Miller Dynasty 200DX as of this day and time.Between tig and stick you can sure do a lot.Miller Dynasty 700Miller 350P with Aluma-pro push-pullMiller 280 Dynasty with expansion card Dynasty 200 DXMigMax 215 Enuff power and hand tools to create one of anything..... but mass produce nothing!!!