[Al Skierkiewicz]

Again,
I don't know of anywhere to get aluminum wire in the size used on robots. (#12-#18) but if you do not oversize the wire, everyone will know when it smokes. A #12 aluminum wire can only handle the current a #14 copper wire can.
Barry,
I have to disagree, aluminum oxide is conductive but that is not the problem with welding. The arc in the weld area will cause significant oxidizing of the weld material and the base material. The melted material cannot bond with the oxide and therefore, an inert gas must be used to minimize oxidation. Ground rods are steel plated with copper ( commonly known as "copperweld" this is also used for antenna wire and ground bonding). You would not be able to drive an aluminum rod into the ground without bending it. (unless it was a large diameter like 1")
The mains coming into my house are also aluminum but are entering an alloy block intended for terminating aluminum wire. The wire is not coated with an anti oxidizing chemical or anything else. Often in older installs, you might find a copper sleeve placed over the wire before insertion into a terminal or panel.
Finally, there is a rather nice spell check on this board that will help quite a lot. I use it all the time.