Sandy,
I've used several things for rust.
First, white vinegar. I got the best results by putting the vinegar and parts in an aluminum tray. Putting it in a plastic tray, well nothing happened. I think the steel/iron, vinegar and AL create some sort of reaction that removes the rust. I've actually watched the vinegar boil around the rusted parts when the reaction gets going.
Evapo-rust. Best thing I've found so far. Easy on the hands and environment according to the label and it does take rust off. My wife bought a quart somewhere after Jenny at Sew-Classic told me about it and I've been de-rusting bits and pieces since.
It also helps if you have a Dremel tool to use the little wire brushes to help the cleaners along.
That's what I do for small stuff. I haven't figured out how to remove the rust on the hand wheel of my #1 66 treadle yet.
Joe