I have found that electrolysis is the best way to rid large chunks of metal -- plane bodies and froggies for example -- of rust.
But what about the little stuff? All those screws, knobs, and the like that hold the plane together?
Well, here's one solution I've come up with.
Supplies:
1 quart-sized glass jar with lid
1 cup powdered citric acid
2 cups white vinegar
some rusty bits and pieces of planes -- washed to remove grease and big chunks of junk
Dump the citric acid and vinegar into the jar, screw on lid, shake vigorously for a few seconds.
Add rusty stuff
Replace lid, but do not tighten all the way, as this will produce a bit of gas. (I have no idea if the gas would/could ever build up enough pressure to burst the jar, but I think it's better not to take chances, as this stuff would make a pretty gross mess to clean up.)
Set jar aside for several days.