I love this method.
Dead easy....
you need.... A plastic container, large enough to hold your rusty part.
Water.
Battery charger.
Soda crystals, (or washing soda), bicarbonate of soda also works.
A piece of scrap metal plate to use as a conducter
Your rusty item.
Fill the container with water, enough to cover your rusty item, mix in a couple of spoons full of the crystals.
Attach the NEGATIVE clamp of the battery charger to the rusty bit and drop it in the water, the NEGATIVE clamp can touch the water or be immersed in it, no problem.
On the opposite side of your container sits the scrap piece of metal with the POSITIVE battery clamp attached. DO NOT ALLOW THE POSITIVE CLAMP TO CONTACT WITH THE WATER, it will get eaten away.
Your rusty item and the scrap piece must be facing each other, so a flat piece of plate is best.
Plug your charger in and turn it on.
It`ll start to give off small bubbles straight away.
Leave it running for a few hours, come back, turn the charger off then check your rusty item...no more rust.
You will have to turn your rusty item around and do it again because it only works on the side facing the metal plate.
DO NOT BREATH IN THE FUMES that are given off from the mixture.
DO NOT SMOKE, GRIND OR WELD anywhere near the container, not only are the fumes toxic, they are also highly flammable.
Your no longer rusty item will now have a black coating, wash this off then dry thoroughly.
If your gonna paint your item, get a coat on straight away, if not, give it a light coat of oil, if you don`t, it will start to rust again almost immediatly
Have fun