[InFlight]

For smaller items such as rusty gears; electrolysis cleanup is very simple, and avoids all the acidic chemicals.

You can probably find lots of instructions out there.

You simply use a plastic tub of water and baking soda solution. You attach the red lead of a battery charger to a sacrificial anode (steel sheet metal). Attach the black lead to your part and make sure their no direct contact. The rust will all be essentially converted back to the base metal, but some will be in the form small loose particles.

Clean it up with fine steel wool & WD-40, or some other polishing method.