Welding tubes like this is not an easy skill under the best circumstances. Just to give you some background I’ve been welding for more than 10 years, and now I work as a cert’ed weld inspector.

I enjoyed reading you article and I have a few comments.

One possible reason for your previous feed issues is A) you are probably using vee-groove rollers, which will cause “wire shaving” with the soft 4043 wire, especially if you’re using a lot of pressure on your rollers. Those tiny shavings in turn end up clogging your guides, tip, and liner. (A lot of people will recommend 5356 with conventional wire feeders because of it’s higher yield strength.) With AL you should ONLY use smooth “U” groove rollers. And use the absolute minimum of roller pressure! You should be able to stop the wire feeding from the tip just by pinching it. It’s also helpful to get teflon wire guides as well. The copper ones, being harder than aluminum may also cause wire shaving.

If you can’t stop the wire easily with your fingers, chances are a jam will break the wire, cause a “bird’s nest”, and cost you a lot of time re-threading the wire. Even if it doesn’t break, trying to push through a hang-up with brute roller force might damage your plastic liner or guides.

The method of metal transfer with Al is quite different than what you’re probably used to when welding steel.

With only a 150 amp welder you’re using “short circuit transfer” with steel. With SCT if your Volts and WFS are tuned correctly, causes the crisp “crackling” sound, like peeling packing tape.

Al MUST be used in the “spray transfer” mode. (SCT doesn’t provide enough “cleaning action” to break through the tenacious surface oxide layer on any aluminum.) The spray transfer mode is very quiet, it sounds like frying an egg. When properly tuned, spatter should be only occasional.

For .030″ Al wire, spray transfer occurs between 500 IPM/22Volts, and 750IP/24V

For .035″ wire, good spray is between 400IPM/23V, and 700IPM/24V

Note that the latter requires between 120 and 200 amps. the former requires 100-150 amps. It’s questionable that your machine can produce reliable Al spray transfer weld with .035″. Therefore, with your underpowered machine I’d advise you to select .030″ wire and get a spool gun (with u-groove rollers) for best results. The small, delicate .030″ Al wire is likely to cause feed issues with traditional feeders no matter what you do.

Also, check out this website by Ed Craig who in my opinion is the world’s master of MIG welding.
http://www.weldreality.com/aluminum-welding-2.htmelding.