Suggestion for MIG'ing Aluminum on Greenhouse

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I got  a Harbor Freight Greenhouse and it got blown over by some 70mph gusts.  I want to put it back together but this time I want to weld the bolted together points and butt weld some of the broken parts.  This is an extruded aluminum that varies from about 1/16" to 3/16".   Is it possible to use my Lincoln WeldPak 100 to do this since it is thin stock and my welder is low amperage?  I was going to order a non-metal liner (actually the aluminum conversion kit for the Magnum 100L gun) and give it a try.  I always hear about using pure Argon and I thought Helium, but would it be that bad to use the 75/25 Argon CO2?The conversion kit comes with .035" aluminum wire but no one ever mentions shielding gas for this kit.  Any suggestions?  Spring is around the corner and I need to get this greenhouse back together.  Also, any advise on cleaning it before welding (it looks clean as it is, is only a year old or less and it has never really oxidized that I can visibly see.Last edited by accentphotography; 02-23-2010 at 10:51 PM.Reason: spelling errorMiller Maxstar 172 TIG (3ph)) converted to Maxstar 152 TIG (1ph), Harris & Victor Oxy/Act, Lincoln WeldPak Pro100, Radioshack 15w Soldering Iron but I want MORE and my wife says
Reply:By the way, my TIG is only 150amps and it is DC so I thought that was out of the question anyways since everyone talks about AC for TIG on Aluminum.  Thanks!Miller Maxstar 172 TIG (3ph)) converted to Maxstar 152 TIG (1ph), Harris & Victor Oxy/Act, Lincoln WeldPak Pro100, Radioshack 15w Soldering Iron but I want MORE and my wife says
Reply:You need 100% argon not 75/25 to do alum mig. Lincoln lists 100% argon in the manual for this.Most people don't have great luck pushing alum wire thru a standard mig gun. If everything is not perfect it can be an effort in futility and very frustrating. .035 is probably easier to push than .030, but you may find the larger wire harder to work with on thin alum. Lincoln lists that machine as good to 12g, but from my experiences with small migs, thats a big stretch and you'd better have a 20 amp dedicated line minimum. I've found that 140 amp class migs needed to be maxed to get decent results on thinner alum (1/16"), and 180 class machines almost maxed to get decent results on 1/8". Real thin alum with mig is very tough as you will blow holes thru if you don't move at warp speed..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:Sounds like I need another idea but so far this is all I have.   I always hear that aluminum needs some serious amps to get anywhere.  I have a 20 amp dedicated line for the welder.  I was hoping that with less amps I might just get by without blowing holes everywhere in the thinner aluminum.  Any voltage or wire speed suggestions for a noob?  Is this lower or higher line voltage?  Fast or Fastest wire speed?Miller Maxstar 172 TIG (3ph)) converted to Maxstar 152 TIG (1ph), Harris & Victor Oxy/Act, Lincoln WeldPak Pro100, Radioshack 15w Soldering Iron but I want MORE and my wife says
Reply:Lincoln has a set of listed parameters for that machine in the manual.http://content.lincolnelectric.com//...r/im/IM782.pdf From experience, usually with small 110v machines, you need to start high on the power and run the wire at about 2x what you would for the same setting on steel. Usually that means that you are on max heat, and the wire feed is almost maxed. Get yourself some scrap alum about the same thickness to practice with. You will push the weld rather than pull it and you will need to move fast, as much as 2x or more faster than welding steel.One other thing, anodized alum doesn't always weld well. You may have to sand or file thru the anodizing to get a good weld. All the alum I do is all plain, so I can't help much there. Also not all alum extrusions are weldable. I forget the exact series right now that are. Since you won't know some of this until you try, it will be a crap shoot if it will work.Not seeing the damage, I can't make any other recommendations on alternate repairs unfortunately..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 appreciate the advice.  It could even be anodized.  As soon as my week long day and night job is done I will see if I can post a shot of the problem areas.  Thanks!!!Miller Maxstar 172 TIG (3ph)) converted to Maxstar 152 TIG (1ph), Harris & Victor Oxy/Act, Lincoln WeldPak Pro100, Radioshack 15w Soldering Iron but I want MORE and my wife says
Reply:The money involved to get that little machine set up for aloominum will not be worth it with end result.As DSW mentioned feeding issues and the fact that it is limited in output = Ed 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:The conversion is not too bad ... $52.00 and includes drive roll, non-metallic cable liner, and contact tips (qty. 6) for feeding .035″ (0.9mm) aluminum MIG wire. Also includes 1 lb. spool of SuperGlaze™ 4043 aluminum MIG wire.  I actually believe I can get the liner for about $12.00, the wire for $6.00 (Lincoln) and I have plenty of contact tips.  I just don't know if the drive roll really needs changing.   I only want to help make the unit a little better than the original nuts and bolts.  Basically keep the nuts and bolts but weld around the joints for a little better rigidity. If I didn't try it would bug me for a while.Miller Maxstar 172 TIG (3ph)) converted to Maxstar 152 TIG (1ph), Harris & Victor Oxy/Act, Lincoln WeldPak Pro100, Radioshack 15w Soldering Iron but I want MORE and my wife says
Reply:I just noticed the Harris and Victor O/A kit at the bottom. Another option for you might be to solder/braze the alum.I've never used thier alum stuff, but it's another posibility to consider. Alum to alum is the last on the 1st chart.http://www.silfos.com/htmdocs/produc...ion_guide.html..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:Now that you mention that ... I have some of the "miracle" Alumalloy ... it welds every aluminum ever made, it dices, slices and give you a happy ending as well.  Hmmm ... maybe I could use a happy ending.   Great idea on the torch thought.Miller Maxstar 172 TIG (3ph)) converted to Maxstar 152 TIG (1ph), Harris & Victor Oxy/Act, Lincoln WeldPak Pro100, Radioshack 15w Soldering Iron but I want MORE and my wife says