Pick up some polishing compound for aluminum and a buffing pad for an angle grinder (if you have one) or a drill.

The big trick, is to keep them polished. Aluminum will start oxidizing pretty much right away. After a few days & weeks, it'll be the dull dingy gray again. Once you have it polished, clean it real well, and then shoot it with some high-temp clear coat.

 

I don't know if I want to have to polish them every few days. If that's the case maybe I'll just head out to the junkyard and pick up a couple semi stacks and modify them.

 

Clean them up real good and spray them with clear coat, that should take care of the oxidizing

 

Another thing about the aluminum I'm worried about is that this irrigation pipe is really thin walled and dents easy. I think tomorrow I'll call the junkyard and see what a couple of 5 foot long 4" pipes would run me. I'd rather have stacks made of steel just the aluminum was an alternative that was pretty much free.

 

You might better just go to Napa and buy a 8' piece of straight pipe and make your stacks out of that it's a lot easier tryin to weld and paint new pipe than used rusty pipe

 

You my friend are not up to date on technology! Welding steel and aluminum together has been possible for quite a few years.

Can I Weld Aluminum to Steel?

Fronius even makes special aluminum to steel welders that aren't huge industrial only units.

 

I learned somthing new today

 

Taken from the site you linked. "Neither of these coating type joint methods are typically depended upon for full mechanical strength and are usually used for sealing purposes only."

And this from Fonius's site. "The highlight of the CMT® process is without doubt its ability to join steel and aluminum. Although the steel base material is only wetted during this brazing process and does not melt, numerous trials always resulted in a break in the aluminum base material, not in the weld seam." Plus I was unable to find a machine capable of this for sale, and looking on their website, it appears is a robotic based setup.

Basically, both methods currently used, do not in fact weld the two metals together directly. Rather, by use of an intermediary (whether insert with the Bimetallic Transition Inserts method or by coating the steel as with the Coating The Dissimilar Material Prior To Welding method) are the two metals joined.

So my original statement stands, Aluminum and Steel will not fuse with each other.

Thank you for the interesting reading though.

Edit:

Not trying to be a dick about it Horns. I've read bits and pieces of the processes before in the past, but never anything to specific. I get asked many times about welding aluminum to steel at my day job (and even in conversations outside of work). It is unfortunently a somewhat mis-understood technique by the general masses. And realistically, 95% (not a factual statistic, just my observation over the years) of your school weld shops, and day-to-day fabrication shops will have this ability or equipment on hand and available. It is still a costly deal that unless you have an ongoing/regular need for it, its just not feasible (similar to Plasma Arc Welding, done it before, but have not seen a shop with one in quite a damn long time).

Cheers, and honestly, thanks for the links and info, it was a good read and something I will have to dig further into.

 

Stacks serve no structural purpose and IF I were to use this method, it would be for sealing purposes only allowing the process to work. But if I still go the route of aluminum pipes here, I would be clamping them to steel pipe. Cummins Smoke 24v had asked how I would weld aluminum to steel. I was aware that it was possible, or shall we say plausible, but wasn't sure how it was done exactly. Indeed you do learn something new everyday.

 

I'm aware that stacks serve no structural purpose, you would still need the weld/joint to be able to hold up to bouncing around of the truck, hitting tree branches, wind resistance, etc. Depending on how much mechanical strength it would be lacking, this joint/weld could more than likely fail.