[KenWittlief]

Straight arc welding, with a stick welder, Im pretty sure the answer is no. You can weld steel with it, you can even braze with it

but when you get aluminum hot enough to melt it combines with the oxygen in the air and turns to a white powder / dust.

Aluminum is normally welded with a MIG welder using an inhert gas. This is a type of arc welder that feeds wire from the center of a handle. It is also connected to a cylinder of argon or carbon dioxide. As you weld the gas flows out over the weld in progress, keeping it in an envelope of the inhert gas. Since no oxygen is present, the alum does not oxidize into dust.

Its also great for welding steel and stainless steel, because you do not need flux wire or flux core welding sticks (which cover the weld with a crusty ceramic like covering to keep it from oxidizing while it cools)

someone correct me if Im wrong on this - technology keeps changing so fast - but Im pretty sure you need a gas envelope MIG wire welder to weld aluminum

But even if it is a plain old stick arc welder, Im sure you will find many uses for it for your team. If steel is too heavy for most of your robot components and chassis, you could still use it for making a robot cart, special tools, or small metal parts on the robot.