electrolytic derusting (EDR) question

I'd go with a big alligator clip, like for jumper cables. How wide are the wheels?

Jim

Grant, Use steel wire and get it on to the wheel mechanically, wrap and twist, dip the whole assembly. If there is still an oxide film under the wire move it and redip.

Ed Angell

Don't have one, really good idea though.

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This one I thought of. It's a great idea too. I don't have any wire that isn't galvanized, though. I actually did solder on a stranded copper wire and it's cooking right now. I'm normally lousy at soldering anything except electronic components but I just kissed the face of the wheel on the disk sander to get a clean spot and my ancient roll of rosin core solder stuck to it fine.

The bubbling action I'm getting isn't very aggressive, although the test run yesterday realized good results in about six hours. I don't have a DC ammeter. I do have an AC ammeter. I'm planning to cobble up a setup using a variac and a rectifier bridge and to put the AC ammeter in series between the variac and the bridge. My brain is too far removed from electronics to be able to suss out the relationship between AC current upstream of a rectifier, and DC current downstream. Anyone know?

GWE

What kind of volts and amps should one use for EDR?

Can you describe the process a bit?

i

I used an old plastic bucket, Arm & Hammer washing soda from Safeway (about

1/4 cup in a gallon), and a piece of old square steel tubing for the anode. I sanded a spot clean on the outside corner of the square tube and drilled a hole near the end, and threaded some stranded copper wire (stripped, of course) through and twisted it tightly. I set the tube on a piece of PVC so the top of the steel was just above the surface of the liquid, with the copper wire (insulated, of course) hanging up over the top of the bucket. I attached another copper wire to the steel caster to be derusted. I drilled a small hole in a flat stick and ran the wire from the caster through the small hole, and put a clamp on the upper side, then layed the stick over the bucket and arranged it so the caster hung inside the steel anode without touching it, connected a small automotive battery charger (red to anode, black to part, connection is critical) and plugged it in. Six hours later I unplugged the charger, removed the part (wire still attached) and ran very hot water over it while hitting it lightly with a maroon 3M pad. Lots of black came off, and underneath - voila - no rust. Except on the caster as my previous post indicated. Now I'm repeating the test this time with the wire attached to the wheel instead of the caster stem.

GWE

For a transformer with a winding ratio of N1 ( pri ) and N2 ( secondary ), Voltage on the secondary ( E2 ) Voltage on the Primary ( E 1 ) Current on secondary ( I 2 ) Current on Primary ( I 1 )

E1/E2 = N1/N2 = I2 / I1 , E1 * C1 = E2 * I2

The first equation is the volttage steps up in the same ratio as the windings.\ The current steps up in the inverse ratio of the windings.

The second equation is just power in equal power out ( neglecting slight losses )

Dan

I forgot to mention that there is a imaginary current on the primary side which is the magnetizing current. You can measure it by disconnecting the secondary from the load and measuring the primary current.. So don't try to measure the primary current and calculate the secondary current.

Dan

Download this handout. Sorry, it doesn't have pictures.

I've elaborated on it a bit more in Grant's post about tin cans.

Orrin

Grant, I have a handful of el-cheapo alligator clips that came out of a junk box. They work well. Because of the polarity, they will not be damaged by submergence in the solution.

You may need to file away the rust in order to make good electrical contact.

Electrolytic derusting works very well on cast iron, less well on steel.

Regards,

Orrin

I don't think you will be able to get inside a hole (the wheel) with this process. If both the wheel and the axle ARE connected to the same side of the power source, then the charges will be the same and no electrolytic action will occur.

Pete Stanaitis

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Grant Erw> I have this old set of casters I'm trying to save. Steel everything, quite

By the way, there is another EDR method rarely mentioned on this NG, not mentioned in any of the normal derusting papers. Orrin, this one may interest you. The method is passive rather than active -- in other words, you don't have to add energy in the form of electricity. No more wires. Simple. Make up some strong hot lye, dissolve in a chunk of zinc, and drop in the rusty part. The zinc reduces the oxidized iron.

There are Web pages about this -- google on lye and zinc and you'll see 'em.

If you don't think you have any zinc, you're likely wrong. Many inexpensive cast metal items are made mostly of zinc. Car door handles, mirror bases, lamp bases, stuff like that. Try a coarse file on it, if it peels away like butter that's the stuff. It's been posted on this NG that lye will bubble on zinc (pot metal) but not on aluminum.

Grant

pennies are thinly copper plated zinc.

They switched to that in 1982. So, 1983 or newer, yes. 1981 or older, no. 1982, maybe.

There is also molasses as a passive bath. You buy the molasses pellet feed that is sold for horses, mix it into water to make a slurry and toss the parts in. Let them sit 1- whatever (depends on how bad the rust is) days and when you take them out wash them clean.

Grant, thank you for reminding me of that method. I'd heard of it, recently, but the recipe I read called for heating a solution of lye. It sounds a bit hazardous to me.

Indeed, most of us probably have zinc all around us and we don't realize it. Die-cast pot-metal items are almost everywhere we look, especially in the kitchen and bathroom.

Regards,

Orrin

Lye reacts very vigorously with Al.