Well, it worked great. I picked up a miter cutting blade for $5 the other day. It's a big cast iron piece and I'll show pics when complete. It was all rusty and grimmy. The vinegar removed the rust really well and quickly.
I tried the same on a cast iron machinists table I got recently. it had a coat of rust and would not work for welding (ground). put some paper towels on and poured the vinegar on, the rust came off and now my ohm meter shows excellent conduction. Before the meter would not move, and sanding the rust was not working... so I'm really happy about this. Cheap, stinks, easily neutraulized with water, just oil after.
You do have to clean the parts first, the vinegar won't cut through oil and grease.