Thread: more rust removal

It's New Year's Day and I've decided I *have* to de-rust an offset vice I want to revive today (after looking at the shockers on offer at Total Tools and Gasweld yesterday).

Can't find and sodium carbonate, nor sodium bicarbonate. There's a Woolworths 5 minutes away that might sell washing soda, but I'm choosing to assume it's closed.

I do have some "Sard Oxy-Plus" which contains 25% sodium percarbonate, which sounds kinda similar, so I assume it'll work.

Pulled the vice to bits, ran it through the parts washer and put it into a storage tub that I'd carefully measured "some" Sard Oxy-Plus into. Hooked up the battery charger and started poking random bits of steel around the edge hooked together with alligator clips. It's up to about 4.5 amps and is producing the expected foul-looking gunge on the surface, I don't think the charger produces the best DC ever made, but it looks to be working.

Any idea how long to leave it in there?

G'Day RustyArc, Happy new year to you and everyone else on the forum. To answer your question, I would pull it now and have a good look at it, and if you have the kit, perhaps a pressure clean, or even a hose off if you have good water pressure. You will then be able to assess it for yourself, to see if it needs a bit more. You will also have removed some of the looser muck, which will assist if any extra electrolytic action is required. It also my pay you to give a bit of a clean to your anodes if you are using iron or steel for them, but if you are using stainless steel or carbon/graphite sheet or rods, you won't have to worry about anode fouling except for floating paint layers.
In any case when the process is complete, you will have a fine layer of material to scrub off your parts, I think that it is either reduced iron or more likely magnetite, an iron oxide, which will quickly turn to that other iron oxide, red rust. You need to be pretty quick to do this, and then get your parts dry, or else they quickly rust on you again. I usually wash with hot water, and sometimes give the hot item a spray down with metho, which helps flush the water away, and then any remaining evaporates quickly with the residual heat, leaving you with a clean, dry and rust free part. HTH,
Rob.

Well, for those who want the full story on using molasses for rust removal, here's the best explanation I've found
(from http://www.answers.com/Q/Why_does_molasses_remove_rust ):

"This answer only refers to sugarcane molasses. Molasses from sugar beets reportedly tastes so foul to humans that it is only used as an additive to animal feed and as a feedstock for ethanol production. Other types of "molasses" are made from various fruits and vegetables.
It makes sense that sugarcane molasses removes rust, which is Fe3O4. Thus, the iron in rust is in the +3 oxidation state, also denoted as iron(III) or Fe(III).

Rust is rather difficult to dissolve because the primary iron oxides hematite and magnetite have zero solubility in water practically speaking, and many of the common iron(III) salts are practically insoluble in water. On the other hand, iron(II) salts (not oxides) tend to be very soluble in water, and chelated iron(III), iron(II/III), and especially iron(II) complexes are usually extremely water soluble, but beware, the solubility of complexed iron may fall precipitously at low and high pH values.

There are three reasons that most grades of sugarcane molasses will usually dissolve rust:

1) Molasses contains a significant amount of copper(II), and Cu(II) will reduce Fe(III) to Fe(II) leaving elemental copper behind as particulate matter of very small size.

2) Molasses contains a significant amount of glucose, which is a reducing sugar that can reduce iron(III) to iron(II), giving the iron a greater propensity toward water solubility. On the average, only about 67% of sugar in sugarcane is sucrose. Virtually all the sugar in sugar beets is sucrose.

3) The final, but most important, reason that molasses dissolves rust and other iron oxides is the chelating agents it contains. The noun "chelant" comes from the Latin word "chele" which means claw. Chelating agents are organic molecules that contain at least two atoms that chemically bind to metals as if the metal atom or ion were being grabbed by a claw; the binding sites are by necessity always in close proximity to one another, and that aids in keeping the metal more tightly bound.

The major amino acid chelating agents in molasses are aspartic acid (tridentate - contains three binding sites), glutamic acid (tridentate), alanine (bidentate), and about two or more percent of valine (bidentate), serine (bi- or tridentate), and glycine (bidentate). Non-amino acid chelants in molasses are the very strong chelants citric acid (tridentate) and malic acid (tri- or bidentate), and other good chelants such as lactate and polyols.

The most common bonding atoms in chelants are nitrogen, oxygen, sulfur, phosphorus, and in certain instances, carbon. Chelants, or chelating agents, bind the strongest to transition metals since those metals possess partially filled d orbitals that are very important in forming bonds to the atoms mentioned above. The strongest ligands, i.e., the ions or molecules bound to the metal, are capable of forming chemical bonds between one of their empty d orbitals and a filled d orbital on the metal. This is in addition to a sigma bond between a ligand's lone electron pair (Every binding atom has at least one lone pair) and possibly even another pi bond between empty, half-filled, or filled p orbital on a ligand atom and a p or d orbital on the metal."

I pulled both bits of the vice out after an hour and a half or so. To be honest, there isn't that much rust, but I also wanted to remove the paint, including some that had been spilt on it over the years. Certainly seems to be working - was able to scrub a lot of the gunk off easily. I've put them back in for another zap.

Then I have to work out how you actually "fix" an offset vice with too much sideways slop. That might need a new thread

when doing electrolisis and expecting a good result it is important to use washing soda for a number of reasons.

It is a detergent of sorts and will attack moderate amounts of oil and other contaminants.....even without the electrolisis...boosted by the electrolitic action..you would be surprised what it will shift.

The single most important reason to use washing soda is its mild anti corrosive action on iron and steel

Washing soda has a mild anticorrosive action on iron and steel without the electrolisis, but when used in electrolisis it leaves a dark grey to black deposit that has a mild protective action and deep into the grain of the metal.

My recomendation is.
Clean the piece as best you can before putting it in the bath.
The cleaner the item is before you start the more effective it will be.

Use a non erroding anode such as stanless or carbon rods....using a eroding material will contaminate the bath, reguce efficiency and put crap on ya job.

Pull the work out and scrub it from time to time.....the electrolitic action will work on the rust and convert it to a soft material that is easily scrubbed off......but the action of the bath is not particularly good at removing this material from the job.
The whole process goes a lot faster and more effectivly if you help it along with a scrub from time to time.

Oh best not to scrub the job in the bath....that would just put crap in the bath and contaminate your solution.

After you think you have got pretty well all the rust off the job and have given it a good scrub and examine.....put the job back in the bath for another hour or so.
This will pick off anything you have missed, lift the crap out of the grain and leave this mild anti corrosive coating.

when you pull the job out this final time....rinse but do not scrub..then blow off with compressed air or pat dry.

This anticorrosive coating is no mirricle......but in areas where clean dry steel will form a light surface rust over night.....this coating won't.

wise to scrub the surface before finishing.


OH...and don't be timmid about the amount of washing soda you put in you bath.......I dump about half a bag in my 30 litre tub.

Use too little soda, and you are kidiing yourself if you think it will be effective.


cheers

Here is a tip for those that don't want to go through the trouble of cleaning their Sacrificial Anodes, I save all our empty steel tin cans and use them as the Sacrificial Anode it saves time and trouble on cleaning the anodes because when the tin can has done its job and is beyond use all you have to do is wrap it up in news paper and throw away in the rubbish bin.

Regards TEZER.

The Sard Oxy-Plus seemed to work well. It does have Stain Targeting Technology.

IMG_0720.jpg

That's very similar to my 6" offset which now sits in the corner. The nut on mine kept twisting and jamming up the vice, needs a more secure locating dowel I think, and of course the jaws are no longer parallel. I've just replaced it with a one of those big red thingies, swivels and twists and has jaws for holding pipe and round bits, hopefully it'll last longer than the offset, it's certainly quite a bit larger.

Back on the rust removal bath, I was wondering if a sheet of carbon fibre would work as an anode???

Originally Posted by emanon

I was wondering if a sheet of carbon fibre would work as an anode???

As a finished product, probably not as properly made the carbon fibre should be encased in (non-conductive) resin. Perhaps try a toolmaking company and see if you can buy a graphite offcut from an edm machine

Michael

Originally Posted by emanon

The nut on mine kept twisting and jamming up the vice, needs a more secure locating dowel I think, and of course the jaws are no longer parallel. I've just replaced it with a one of those big red thingies, swivels and twists and has jaws for holding pipe and round bits, hopefully it'll last longer than the offset, it's certainly quite a bit larger.

This was the only vice on the farm for a long time, and had a pretty tough time. There's now another vice more suited to the abuse this one got, but I have been eyeing off those spinny ones with the two sets of jaws...

I had been going to just replace it, but the ones on offer were terrible quality, so I thought I'd have a closer look at this one. It turns out it should be pretty simple to sort out - there's little dots of welds in the four places that the rail pushes against when tightening, and they've worn down. All I need to do is renew the lumps of weld and file them down until the jaws meet parallel in both dimensions.

That's a good tip, I'll have to have a look at mine to see if I could add dots of weld to straighten the jaws up, or perhaps drill and tap and add adjuster bolts. It's used as a bashing post mainly and I'm loathe to bash the new one.
I assume the spinny vice you speak of is the same as the one I bought. They're called mechanics vices I believe, the biggest advantage is they will spin and/or tilt - the biggest drawback is they will spin and/or tilt.

The nut is at the rear of the vice and is an integral part of the clamp which prevents/enables tilting. the clamp surrounds the round slide and can be tightened via two 6mm allen heads. I've now replaced the allen heads with threaded rod and a couple of nuts to tighten the clamp. Time will tell how good it is, I passed up a cheaper Record for this one.

Here's a thought for an anode, supposedly lasts quite a while:
http://www.ebay.com.au/itm/1pcs-Grap...item41849ab361

Originally Posted by emanon

I assume the spinny vice you speak of is the same as the one I bought. They're called mechanics vices I believe, the biggest advantage is they will spin and/or tilt - the biggest drawback is they will spin and/or tilt.

Yup. This is the Record one I've seen in a few places:
http://www.bunnings.com.au/irwin-125...35505_p5860123

Which actually seems to be remarkably decent quality for 150 clams.

I should have taken some pics of the shockers I saw in Total Tools and Gasweld.

As for the offset vice calibration points, here's some pics:

IMG_0723.jpg That's the bottom and you can see traces of the old (original?) blobs of weld on each side.

IMG_0724.jpgThe front left side - you can see a slightly porous spot, a bit lower than I'd have expected.

IMG_0725.jpg The rear right side - with this one you can see some of the blob on the edge of the steel. Again, I assumed they'd try and centre the blob on the contact point, but maybe it doesn't matter that much.

As for anode material, I started out using little lengths of 5mm deformed bar I'd cut off some reo mesh, then moved to using some 1.6mm sheet offcuts, but realised afterwards, the bits of sheet were now pitted and kind of unusable, whereas there's a chance I'd have found a use for them otherwise.

So maybe SS or graphite/carbon is the go for the future.

I have no doubt that the graphite anodes you linked to would last, but they seem very expensive to me. In my experience you want as big an anode as you can get. I have used a Stainless steel trough about 1200x600x220mm as both the containment vessel and the anode, and that worked well. When I tries using scrap iron, (lumps of steel channel about 500x100x45, and bits of deformed bar for concrete reinforcement) I found that I needed to move the anodes around or alternatively shift the workpiece so that all parts of it got equal de-rusting, because the tendency was there for the parts furtherest away from the anode(s) to be slower to clean up. That was never an issue when the part was surrounded by the anode/tank, as everything was pretty well equally exposed to the process.
There is much cheaper graphite around from time to time on eBay, and Micheal G's suggestion of approaching EDM practitioners is one I will probably follow up myself, thanks Mike
On the subject of what chemical to use for your electrolyte, washing soda is cheap, widely available and safe to handle, use and dispose of. Caustic soda will work very effectively too, it will cut grease, (turns it to soap) and also protect the iron and steel from rusting. It is more hazardous than washing soda to handle, but not so bad as to make it unmanageable. you will not need much of it, and provided you use eye goggles and some rubber gloves if you pick up flakes with your hands, you would be fine. Have some clean water available for eye wash and also for irrigation of spills on skin as a precautionary measure, just in case. The caustic soda solution will eventually turn from sodium hydroxide into sodium carbonate - the same as washing soda, as it absorbs and reacts with carbon dioxide in the atmosphere. When mixing acids or alkalais, always add the acid or alkalai to the water, never the other way around, and if you do mix some caustic soda solution, so that you can add small quantities of that stock solution to your electrolyte bath to set the current as mentioned below, avoid using drink containers, and ensure that you properly label the container, so that no little people suffer awful injury from consuming the stuff. Keeping it in a locked cupboard helps in that regard too.
I have made the strength of the electrolytes the way I set the current from by very basic power supply. I have use an old Arlec Charger4 as my power source as previously mentioned. It has a rudimentary ammeter, and also a thermal cutout which operates if more than 4A on the meter flows in the circuit. I just add more chemical till the current gets to about 3.5 A and leave it at that. The charger keeps operating and does not cycle if I keep the current at 4A or below, and I would expect that your vice would take less than 24 hours to do in my setup. From memory about 1 teaspoon of caustic soda would do a bin around the size of an average kitchen sink, while a laundry tub might need a tablespoon or so to work with my charger. I would still use washing soda for preference, but if none was available to me, I would have no hesitation in using caustic soda, taking the precautions I have outlined. For small quantities of caustic soda based electriolyte, some plain label soda water would add lots of CO2 and convert the hydroxide to carbonate, which you could send down the drain or bucket over the lawn, particularly if like me, you have acid soils in your area.

The Record vice you linked to is slightly different from mine in that it has a tilt lock lever on the the side. The quality looks pretty good though, I suspect I have one of the shockers you mentioned.

I'm a little concerned about the toxic issues with using S/S as an anode which is why I suggested the Graphite, may just have to use bits of scrap I think. What is an EDM machine?