Welding Tips and Tricks

New to the forum and have a question about aluminum welding equipment. I am quite proficient in stick and mig but have never ventured into aluminum welding. It is not something that I will be doing a lot of. My current project is a small dual chambered tank that will need to hold about 20psi. The equipment I have in my garage is a Lincoln DC250 with an LN7 wire feed on top, and the usual acetylene torch . It dates to the early 80's when I was doing structural steel. I have talked to Lincoln who tells me that there is no way to adapt a spool gun to the LN7 but experience has taught me that with the help of Walt Disney's mouse most anything is possible. Lincoln told me that if I purchase a 10 foot cable and gun it MIGHT push .035 aluminum wire through it without bird nesting the wire. I am not willing to invest around $600.00 on a might. Has anyone out there managed to successfully adapt a spool gun to an LN7?

Also what about low heat aluminum solder? the base material for the tank will be 4" square aluminum tubing with about an .065 wall, but it will need to be water tight.

If I can get set up inexpensively enough I would like to get the equipment to do it myself because I am finding more and more that I need to be able to do it rather than getting it set up and having someone else weld it.

Any help will be appreciated

If its not too thin your simplest and cheapest option is to stick weld it. Takes a little getting used to but works well once you get the hang of it. My local store carries a product called Smoothcote 34.
I know some people run Aluminum wire in MIG using a teflon liner. Keeping your cable length shorter and straight should help too. Ive never tried it.
The spool gun will not ADAPT to the LN-7, it will replace it- you need a spool gun with the same type of brain cable, gas line, and lead connection as the LN-7 and it will plug to your power source same as the LN-7. Main issue I can think of is that your power source probably does not have an internal solenoid for the gas so you will either have to add an inline valve or just turn the gas on and off at the tank.
I have also brazed/soldered (not really sure what to call it) aluminum with some cheapo rods off the internet. It is pretty easy to make stuff stick for small repairs but not practical for fab because the stuff melts and falls apart when reheated causing the piece to fall apart if more than one single-sided joint is required.

oldguy44 wrote:Lincoln told me that if I purchase a 10 foot cable and gun it MIGHT push .035 aluminum wire through it without bird nesting the wire. I am not willing to invest around $600.00 on a might.

Also what about low heat aluminum solder? the base material for the tank will be 4" square aluminum tubing with about an .065 wall, but it will need to be water tight.

No need to spend $600 for that solution....you can buy a decent 10' torch with a Lincoln back end for $100 on eBay or Amazon. .045 wire would be better for pushing in that situation.

The problem is that MIG really isn't a great solution for aluminum that thin. The post you made on the other forum has a lot more detail about that part of the discussion.

I can easily change the thickness of the base material as I have not purchased it yet. How do I identify a torch with a Lincoln back end and does it need a specific liner? Is there anything shorter than a 10 foot cable because I can get my machine right next to my assembly table and apparently the shorter the better. How about shielding gas with aluminum, I run argon co2 with steel wire.

oldguy44 wrote: Also what about low heat aluminum solder? the base material for the tank will be 4" square aluminum tubing with about an .065 wall, but it will need to be water tight.

1/16" 1.6mm is way to thin for mig or stick imho.
pulsed mig or tig is the way to go.
otherwise increase the thickness to say 1/8" 3mm or thicker, which is good idea for anything pressurised.
even then your looking at 0.030" 0.8mm wire with a spool gun.
0.040" 1mm wire will run through mig gun with short lead easy enough, even with single drive roller. but i found i could not get it dialed in for 1/8" 3mm material on my machine. spool gun with .030" 0.8mm worked a lot better for me.

uses argon gas, not mig gas.

A lot of wire feed systems won't feed aluminum wire fast enough to get into the spray transfer needed to weld aluminum. Around twice the speed for welding steel is needed. That may be your biggest hold back on the equipment you have. To compare, I use a newer Hobart 190 for mig and have a spool gun setup for it. Wire speed goes from 10 to 100. I can weld steel from 30 to 50, but need 70 to 100 to weld aluminum. I know those settings are arbitrary since I don't know the inches per minute. It can be done with mig by preheating the material to help eliminate cold starts. The best option would be to get a tig setup. Certain welds are just better with tig. I now have both and use both where they each work better. Mig is great for fillet welds even on thin material because it's hot and fast. Tig is great for tacks and outside corners that don't need as much heat. Only you know your future plans. Welding aluminum well will cost money and time practicing. Research it well. Could be a good investment.

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