Any tips for bare steel contact not rusting?


2010-08-21 7:59 pm
I would be sure a ground connection site on a steel chassis is clean, then drill a hole and rivet a terminal lug there and solder the ground wire to the terminal. With a sufficiently high powered iron, you could solder the ground wire right to the steel surface, too.
If you grease the parts you screw together, you can conserve the contact points for years.
I´m doing work on vintage cars for 40 years now and that keeps contacts clean and rust free. Any all purpose grease will do. As an alternative you could use conservation wax for cars available in spry cans, which basically has the same effect, but penetrates better and dries after a few hours. In any way it is important to use it before tightening things up. Not just a dash on the finished connection.
I have measured such contacts and there is no higher resistance, as some may think grease or wax might insulate.
Bare mild steel will rust extremely easily, which is why passivated steel or cadmium plated steel is commonly used for chassis's and assemblies. Black mild steel is naturally protected by black iron oxide layer - this needs removing to make good electrical contact of course, removing the protection where you want it.

And another way to protect steel is powder coating, but that's usually after assembly.
Ordinary paints and varnishes aren't great at preventing rust, but will fare well indoors (unless its a very humid situation). Outdoors you need anti-rust formulations for paint on bare iron and steel, otherwise its just a matter of time...

I've just been restoring some rusted outdoor machinery as it happens, if only titanium were cheaper, it doesn't corrode at all, even in seawater!