Now lately I have been hearing about corrosion caused by dissimilar metals in contact with each other, so I went to the thought of using stainless rivits through aluminum into steel tubing. can anyone tell me the proper way to fasten aluminum sheeting to steel tubing? in the matter of a snow cat cab. I also thought that the proper way would be to paint the tubing before hanging the sheeting and then putting a coat of paint over the whole outside.
any help would be appreciated.
Battdad,
What you're describing is called galvanic corrosion. A few years ago I started a thread about it on Tuckers:
http://www.forumsforums.com/3_9/showthread.php?t=44452&highlight=galvanic+corrosion
That thread also talked about rust issues with Tuckers, but as far as preventing galvanic corrosion, you need to do something to "break the bond" between the dissimilar metals. The 1979 and 1980 Tuckers I've owned all use raw aluminum sheet metal riveted to the raw steel frame for the roof and doors. Those year Tuckers use a clam shell style hood and the center portion of the aluminum hood halves are riveted to the steel hinge. The floors are also aluminum, and they are screwed to the steel frame.
My snowcat buddy and I drill out all the rivets, sand the steel frames to remove all rust and corrosion, and then spray them with a couple coats of primer. The rivets Tucker used were steel blind rivets (they're basically POP rivets) but this is also a problem area. The rivets have a mandrel that when pulled on by the rivet gun, compresses the rivet and eventually breaks off. The portion that remains in the rivet can (and does) fall out. That leaves a nice hole in the center of the rivet. Water can then enter the support frame. We have replaced door frame sections that were distorted by water intrusion. Enough water filled those steel square tubes that when it froze, it expanded the steel to the point it was rounded and split the tubing.
In reassembling the machines we use an auto body seam sealer on top of the painted frames (which also helps prevent a bond) and closed-end stainless steel blind rivets on the hood, roof and doors. The ends of these have no hole and the mandrel's remains can't fall out the back of the rivet. These rivets can be a bit difficult to find, but they are out there. If you go with rivets, I'd also suggest getting a pneumatic rivet gun. Steel and stainless steel rivets that are 3/16" in diameter take a lot more force to compress than an aluminum POP rivet. Using a hand powered rivet gun you'll get sore fast and/or have forearms like Popeye when you're done.
I think Teamster's method is excellent, but in our case we would have literally hundreds of holes in the aluminum and the steel frame to weld closed.