Ok now if THAT dont work here is another way. I was waiting to see pics of the tool and parts before saying much but here it is.
Electrolysis, A plastic tub; iron electrode (REBAR) or steel bar, water,Sodium Carbonate (Arm and Hammer LAUNDRY soda if you were wondering),battery charger and some way to suspend the object (chain or wire).
About a half cup to 5 gallon of water (well mixed). The iron or stainless electrode is connected to the positive (red) terminal. The object being cleaned, to the negative(black). Submerge the object, making sure you have good contact. DO NOT GET IT BACKWARDS UNLESS YOU WANT YOUR ITEM TO DISAPPEAR!! Make connections on a part of your electrode that protrudes out of the solution. The electrodes must not touch the part.Depending on the amount of rust, a few hours to over night is needed. Then depending on the objest a brillo pad or somthing under running water maybe needed for clean up.
As soon as you turn it on you should see bubbles coming from the part being unrusted. This is pretty safe but unless you liked the film of the Hindenburg going down dont get flame near it. Hydrogen tends to burn. I say that as i have had this set up and running 20 ft from a lit coal forge. I still wouldnt stand over it with a cigerette in my hand if I smoked or a BBQ steak right next to it. That is ONE way and the very best way to get the cleanest steel but there are a few other tricks . Soaking in vinegar over night is one. Vinegar is a very mild and yet very effective acid the down side is that it will look pickled afterwards so a bit of simichrome or flitz will be needed to bring it shiney again. Before I do ANY of this i go to the wire wheel first, sandblaster second, if its horrid bad or a very large peice as can happen around a blacksmith shop, Electrolysis it is. If infact none of that works find your dumbest friend do to what I suggested in the above post. Electrolysis can be done in as small as a gallon of soloution for small parts to a hundred gallons for big peices, for instance like a iron gate.