I am not expert by any means, but I thought I would toss out a couple of things that might interest to some of you on rust removal. This can apply to most any ferrous metal, not just restoring old machines. It could be used on hand tools such as planes for example.
I will start with my favorite rust removal tool. A wire brush. Nothing fancy or high tech about it but it works. I have used a wire wheel mounted in one of side of a standard bench top grinder for a long time. I just made this up a couple of weeks ago.
This is an old motor I had laying around with a built in switch in the base. Perfect for this application. I mounted it to scrap piece of pine so I could take it where I was working, my temporary saw horse bench in this case and clamp it down. Then I store it out of way when I don't need it.
This is a Craftsman 1750 RPM motor. The lower motor speed make it safer in my opinion since it has no guards. It doesn't seem to grab as hard and try to pull your hand into it. It has a couple of arbor adapters on it and medium stiffness wire brush on one side and a scotch bright pad on the other.
Since there are no guards I like the softer wire brushes. They don't clean as aggressively but they don't tear up your skin nearly as bad either. And if you use this you are going to hit your hand with the wire wheel. If I have a tool rest I like the stiff brush because it cleans faster.
On the other end is something I just started using. A scotch brite wheel. I found this at the local surplus store. I like it so much I am going back and buy an bunch and stockpile them! They will polish up a machined surface very nicely. They remove the rust too, I am just used to the wire wheel so I use it for that.
This is rusty piece of cast iron off my jointer I am restoring. I spent 2 or 3 minutes cleaning the small area. Probably takes 5 minutes to do the whole part. You can see the amazing difference the wire brush made. That surface it now ready for primer. I took the scotch brite wheel to the machined surfaces to clean them up an polish them when I finished it.
I don't have pictures but on large pieces I use a knotted wire wheel or knotted cup brush in an angle grinder on them. Same principle, just a larger scale.
Electrolysis, a very effective method of cleaning old rusty parts. It just takes a dumb battery charger*, a tank of water and and some soda to make the water more acidic. It's probably the best method around but it's not nearly as quick as the wire brush. I will skip the details as there are lots of web sites with the details. Just Google something like "Electrolysis rust removal" Be sure and include rust of you get a lot of unrelated things like hair removal.
*Dumb Battery Charger is one without the automatic controls. You don't want one that shuts down when the battery is charged. You want one that is dumb and just keeps supplying power till regardless. This usually means the cheaper ones.
Here are a couple of photos of my latest tank. I have used small plastic boxes and commonly use the storage containers. I even made one on the trailer out of concrete blocks and plastic sheeting for a large DeWalt radial arm saw base.
The second photo shows what happens after about 36 hours. Smaller parts won't take as long, but this is the top of the 12" jointer. It is ready to be taken out and swapped end of end since the tank was not quite large enough.
There are other methods, these are just my favorites.