Help a beginner mig aluminum

Hi Guys, I picked up a Century 90 amp wire feed mig welder at a yard sale. I have cleaned it up, replaced the switch for the wire feed drive.
I welded a couple of pieces of iron together with about 5 ft of the wire left on the spool. I want to be able to mig aluminum. The unit has the regulator and gauge, so I need to buy/rent a tank of you tell me gas? And a spool of wire for aluminum. I need to know what materials I need to start welding aluminum. I know this is a lightweight unit. I just hope to gain some experience welding 1/8 aluminum. Mike PS. I paid $30 for the welder a vacuum pump and a set of refrigeration gauges. I know I'll spend much more before I get anything welded :-)
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amdx wrote:

I'm not a MIG expert, but 90A is marginal for steel, and aluminum typically requires a good deal more amperage to successfully weld than steel does. MIG welding of aluminum is typically done with much larger machines and often with spool guns for the smaller machines, or push-pull setups for really large production stuff. I don't think you stand much chance of successfully welding aluminum with a 90A machine and no spool gun.
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Is there a real difference between a wire feed from the base and one from a spool gun? Mike
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amdx wrote:

In one word YES. The problem with aluminum is that it's SOFT. Want to know what the difference between steel wire and aluminum is in a long feed line? Take a piece of good old spaghetti, Raw you can push on one end and the other end moves the same amount and straight. Steel wire is like that. It is stiff so it doesn't cause a lot of problems.
Now cook the spaghetti. Now try pushing on the end and see if you can get the other end to move the same! This is what aluminum wire tries to do inside the wire feed. It will birds-nest at the feed OR it will have small bends all the way through the liner and not feed at all.
With a a spool gun the feed length from the roll to the work is less than 6" in most guns. It comes off the roll, into the feed rolls (usually 2 sets on a spool gun) up a short feed tube to the tip. Very small chance of problems.
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Steve W.
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The wire is very soft. The distance it has to go in a spoolgun is around six inches. You cannot push it through a regular long gun unless you are running some of the harder aluminum alloys. Or at least that was my experience with a MillerMatic 200 with the matching spool gun. I never got it to run right.
I did notice, though, that it welded better on successive passes as the base metal got warmer. If you are going to do much aluminum, I would suggest you investigate a TIG, or a better MIG unit. There have been advances since I owned mine in '84 to '86, and I understand the new stuff is awesome for what the regular garage operator can get.
Steve
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amdx wrote:

It isn't nearly big enough for 1/8" aluminum. You MIGHT be able to do 1/16... The smaller the weldment, and the more you could pre-heat it might affect this.
You would use pure Argon gas.
You would want to get a new liner, drive rolls and tips and keep them ONLY for Aluminum use.
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amdx, sell that POS for twice what you paid.use the proceeds to buy a buzzbox for a great price, sell the buzzbox for twice more, use the proceeds to buy a old three phase welder at a great price, sell it for twice more, buy a Snapon MIG welder for that, sell it for 2x, and score a great deal on a decent welder lime MM250 or Syncrowave.
i
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Ignoramus10488 wrote:

2nd on the Syncrowave :)
Iggy, when are you going to start touring doing lectures at hotel conference centers teaching people your up-selling techniques?
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The Spoolgun I had on my MillerMatic 200 was used only for aluminum, and the liners were 6" lengths of hollow plastic tubing.
Steve
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Steve B wrote:

Yes, that is the same setup I have, however, the OP does not have a spoolgun. So if he wants to try Al in his 90 amp machine (something I don't think will turn out well) he will want a dedicated liner and new drive rolls. That is the setup they used in our shop with a Handler 120 before I brought in my MM 200 and spoolgun3. Using Aluminum on a small MIG works OK but proper adjustment of the drive roll pressure and keeping the gun cable as straight as possible are a real requirement.
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I have heard a lot of people say that they have trouble with aluminum through a long gun. Let's hear from some of them who have practical experience with those.
Steve
Visit my blog: http://cabgbypasssurgery.com
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On Thu, 22 Apr 2010 19:16:06 -0700, "Steve B"

Gunner..raising his hand while using the other hand to untangle a wad of aluminum from his DanMig 200
And Running NICE aluminum beads with .065 aluminum on his Cobramatic Prince XL, Spool Gun and Cobramatic Husky feeder
"First Law of Leftist Debate The more you present a leftist with factual evidence that is counter to his preconceived world view and the more difficult it becomes for him to refute it without losing face the chance of him calling you a racist, bigot, homophobe approaches infinity.
This is despite the thread you are in having not mentioned race or sexual preference in any way that is relevant to the subject." Grey Ghost
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Steve B wrote:

My experience is that it will work, IF you have a clean liner, new and properly adjusted drive rolls, and you keep the cable from the spool to the contact tip as straight as you can. Swapping the liner is for two reasons, one, new liners have less friction, two, you want no steel or copper particles to contaminate your aluminum while it runs down the tube.
But even when it works as well as it can, it isn't nearly as good as a spoolgun, unless you factor in that it is way less bulky, which can make a difference in some cases.
If you have the choice to use either one, like I do, you will pick the spoolgun except in very unusual situations.
Of course a push/pull setup is the best of both worlds. Wish I had a cobramatic gun...

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My understanding is that all aluminum MIG welding is done in Spray Mode. That is where once the welding begins there is a continuous arc. Not the usual short and burn back. Since aluminum is softer than steel, you can not use really thin wire. So in practice Aluminum MIG welding requires probably a minimum of 150 amps and you would probably be more successful with a welder capable of 200 amps.
However Lincoln claims you can MIG weld aluminum with a small welder.
www.lincolnelectric.com/knowledge/articles/.../compactmig.asp -
The above and Google should get you to the right URL.
Dan
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In article

There are 3 transfer modes for aluminum MIG.
Globular, Short Circuit, and Spray.
Globular is medium voltage, low wire speed, and is like slow aluminum TIG done with a MIG gun. The aluminum seems to fall out of the gun in little blobs that fill up the weld area. It is mostly used for build-up or filling holes and gaps.
Short Circuit is medium Voltage, Medium Wire speed, and is just like most steel MIG. It is the most common process for aluminum under 1/4" thick. Sounds like steel MIG.
Spray process is high voltage, medium wire speed, and is mostly used on aluminum 1/4" and above. Spray should sound like a high pitched whine coupled with an air nozzle. It is very hot, and is tricky to use on small parts due to the excessive heat buildup.
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I am not sure where I got the idea that all aluminum MIG welding was done in spray mode. Glad you corrected me, Ernie. How are you coming on your welding course?
Dan
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In article

Which one?
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wrote:

I could only get my MillerMatic 200 W/ Spoolgun to run right and really hiss when I was welding on 1/4"+ plate. Everything else just collapsed. I managed to repair the bow of my boat with it, but never really mastered it. The consumables were expensive, and not cost effective unless you had a lot of dough, or a decent amount of jobs for it. It sat for a long time until I sold it. Don't even remember now.
The globular transfer and mid range just would not produce an acceptable looking weld, really some narly looking stuff.
Steve
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