spot welding

Actually, aluminum can be spotwelded. I worked in an aerospace company and we did a lot of spotwelding of aluminum, most especially on P3's and CP140 aircraft. All of the skins on the control surfaces on P3's are spotwelded. We also did a lot for Dash 8's for DeHavilland, as well as Trackers, Arguses, and some for CF101 jets.
Spotwelding aluminum can be accomplished ony when the metal has been degreased, etched clean (deoxidized) in a sulfuric acid solution and rinsed and dried prior to welding, and then, depending on the class of weld, it must be done within 12, 24, or 48 hours of cleaning. The spotwelding machines have specific heat, (amperage) pressure, and dwell times preset by computer, but can be done manually. The Sciaky machines we used were once all manual controls. Spotwelding aluminum has been done since the 1950's.
Any attempt to use a commercially available machine (i.e. body shop spotwelder) will not work.
 
After reading your post I googled this. Apparently you need way more heat/amperage at a much ,much quicker weld time. It looks as if the machines cost $60,000 . So basically as a hobbiest you don't spot weld aluminum. But there is lots of info on it.
 

Thanks guys. After I posted this I Googled it also, and I see it's beyond what I can do with what I have.
My spot welder is a simple hand held one that you squeeze until you think the weld is done. I've been using it for maybe 25 years with good results.

Dusty
 
(quoted from post at 19:32:58 03/15/13) You don't. Spot welding works because of the resistance in the metal and aluminum has none, or very little.

Should read because of the lack of resistance in the metal. Aluminum has MORE resistance, not less but I don't think that's why it doesnt't work. It is more of a metallurgy thing.
 

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