Stick electrode holder

[joshuab]

Here's a stick electrode holder that I built. I made it from a piece of old rusty pipe that has been out behind my barn since I moved here.



So, what could possibly be interesting about this totally rudimentary and obvious project? The pipes were SO covered in rust that I decided it was a perfect time to try electrolytic rust removal for the first time. In case you're not familiar with it, electrolytic rust removal is kind of the opposite process of electro-plating. Instead of using electrolysis to cause stuff to bond to the surface of your metal, you use reverse-electrolysis to remove rust from the surface. Basically, the process converts the rust back to elemental iron. It's not quite that simple, but that's the gist.

This process is appealing for a few reasons. The first one is that it is basically zero labor. It takes time and is slow, but it's way less elbow grease than grinding and grinding and grinding on a piece. Also, I hate grinding round tubing clean, because there are no flat surfaces to just wipe off. The other reason electrolytic rust removal is appealing is that it only removes the rust. It doesn't damage the underlying steel at all. This would be useful if you had an antique tool or something that you were trying to restore. Any steel that had been converted to rust would be permanently gone, but no additional damage would be done by the rust-removal process.

If you want to read a more detailed description of the process, you can do it here: http://myweb.tiscali.co.uk/andyspatch/rust.htm



In electrolytic rust removal, the object to be cleaned is the cathode, and you need some sacrificial iron/steel anodes to complete the process. Rebar is a common choice. I decided to use a five gallon bucket as my container, so I used a jigsaw to cut a round piece of plywood as a lid, and then drilled holes and stuck rebar through them. The more anodes you use, the faster the process will go. Also, the process is line-of-sight, so I put an additional anode in the center, to clean the inside of the pipe.



Wiring them up was the single hardest part, because I couldn't find a good piece of wire to use. Finally, I remembered I had some speaker wire in my basement and rigged that up. I still couldn't really properly attach the wire to the rebar. I cut slots in the ends with a zip wheel and then wrapped and taped, but it was pretty shaky. I also drilled holes in the lid because the electrolytic process produces some hydrogen gas, and it needs to be vented. Really, it's probably too small an amount to worry about, but why take chances.



Here it is all set up. The best thing to use for a current source is a 12-volt or 6-volt battery charger. The problem is that if you have a "smart" charger, it will be able to tell that you don't actually have a battery in the circuit, and it won't kick in. You can fix that by wiring a battery in series, but then the charger needs to have enough output to compensate for the draw, which my little charger did not. In retrospect, maybe I could have wired up some light bulbs in series to reduce the current of the circuit to a level that the charger could keep up with. Ohm's law, and all. Anyway, at first, I hooked up my 12 volt battery and left the multimeter in circuit so I could detect when the battery was low and needed to be recharged. Then I put the battery on the charger and swapped it for another one. This was tedious and annoying.



So then I dug around in my junk box and found a 12 volt, 1 amp transformer for some long-lost piece of hardware, so I cut off its plug and hooked its leads directly to the circuit. I also stuck a 12 volt light bulb in the circuit, to reduce the current a little bit and also to give me a visual indicator that the process was still occurring. The transformer was still running at about 1.5 amps, and it burned up after some hours of this, but who cares. It got the job done.

Incidentally, if you have a DC welder, it can be set to the lowest output setting and then used as the current source for this process. One problem there is that a battery charger may have short circuit detection, whereas a welder won't, so you have to be really sure that there won't accidentally be a short. The other thing is, I wasn't willing to chance my expensive inverter welder on this process, but if you have a buzz-box, you're good to go.



Here's the result, with "before" on the left and "after" on the right. The "before" has been cleaned with a wire wheel, but not ground at all. The "after" is a little misleading, because it immediately (like, literally a minute later) had a patina of rust on it, but you can see how ridiculously clean it was coming out of the bath.

[joshuab]

I would be interested if anybody from Everlast could weigh in on whether it would potentially damage the unit to use it as a power source in a circuit like this. Let's assume we've got a 10-amp fuse inline so that if there's a short, it breaks the circuit. Let's also assume it's set on minimum output (5 amps or whatever). On the one hand, an inverter welder is a Sensitive Tool (etc...). On the other hand, it outputs DC power... does it really care whether it's pushing DC through an arc gap or a bucket of electrolytic solution?

I mean, I don't expect you to say, "YEAH! GO FOR IT! NO PROBLEM!" I expect you might say something like, "Doing this will void your warranty, but that being said, it's probably not going to hurt anything."

[performance]

To answer your question, I have no idea. lol. It's not usual to see this sort of application, and I imagine that at some point something would happen with long arc on times eventually.

BTW, be sure to fill in your "location" as that's something we like to see if possible as it helps each other to get a general idea where people are and shows perspective customers if there are other customers in their area. Thanks.

[Rambozo]

I would be interested if anybody from Everlast could weigh in on whether it would potentially damage the unit to use it as a power source in a circuit like this. Let's assume we've got a 10-amp fuse inline so that if there's a short, it breaks the circuit. Let's also assume it's set on minimum output (5 amps or whatever). On the one hand, an inverter welder is a Sensitive Tool (etc...). On the other hand, it outputs DC power... does it really care whether it's pushing DC through an arc gap or a bucket of electrolytic solution?

I mean, I don't expect you to say, "YEAH! GO FOR IT! NO PROBLEM!" I expect you might say something like, "Doing this will void your warranty, but that being said, it's probably not going to hurt anything."

My two concerns would be duty cycle as was mentioned, and high voltage. Since that is a CC source, the voltage is dependent on the resistance. I have no idea what the resistance of your derusting cell would be, so the welder might be asked to produce high voltage like a long arc condition. It seems inverters don't like that and will even shut off if you have too high a voltage. Also the high voltage requires more safety precautions. I would stick with battery chargers.
I have run into those same problems with "smart" battery chargers and have often been able to add a switch to allow "dumb" operation for things like testing 12V devices or charging completely dead batteries.

[everlastsupport]

Smart chargers normally start with no power to the clips, then they check polarity at clips, no short at clips and then ramps up current (to avoid a spark; hydrogen gas boom).

If you use a load (battery, power resistor, etc.) Most will fire up and stay on as long as you are pulling a small amount of power.

[geezer]

The only question I have is,,,did you drill two small holes in the bottom plate to let any moisture run out,,in case some should get in..

[joshuab]

The only question I have is,,,did you drill two small holes in the bottom plate to let any moisture run out,,in case some should get in..

I didn't. I guess it's a good idea, but since it's mostly stored indoors, I didn't really think about it. Just have to make sure the holes are smaller than 3/32"!

[joshuab]

Smart chargers normally start with no power to the clips, then they check polarity at clips, no short at clips and then ramps up current (to avoid a spark; hydrogen gas boom). If you use a load (battery, power resistor, etc.) Most will fire up and stay on as long as you are pulling a small amount of power.

Thanks for that. I didn't know what kind of things they would check for. It sounds like even a light bulb in circuit as a resistor, to prevent the charger from sensing a short, would do the trick. I'll give that a try next time. The process actually works better at low amperages--it takes longer, but it consumes less of the rebar. And being able to use the charger would allow the process to run basically forever without interruption.

[Rambozo]

Smart chargers normally start with no power to the clips, then they check polarity at clips, no short at clips and then ramps up current (to avoid a spark; hydrogen gas boom).

If you use a load (battery, power resistor, etc.) Most will fire up and stay on as long as you are pulling a small amount of power.

That may be true of some, but I've run into many that require a triggering voltage at the clips to insure they are properly connected to a battery to begin outputting current. These types will not even light bulbs or run other devices. They will also not charge a battery that is completely dead or has a voltage below the trigger (about 1.2 volts as I recall). These are the ones that I have had to modify to allow testing of things like window motors and other auto parts, or to try and revive totally dead batteries. Sometimes you can parallel a capacitor across the output, but more often you have to bypass a portion of the protection circuit. Some brands are easier to figure out than others.

[joshuab]

These types will not even light bulbs or run other devices. They will also not charge a battery that is completely dead or has a voltage below the trigger (about 1.2 volts as I recall).

Come to think of it, I recall that my charger's manual says it won't work on batteries below 3 volts, so there you go. Still, wiring a battery in parallel would be fine, as long as overall current draw was reduced to something that the charger could keep up with.

[joshuab]

My two concerns would be duty cycle as was mentioned, and high voltage. Since that is a CC source, the voltage is dependent on the resistance. I have no idea what the resistance of your derusting cell would be, so the welder might be asked to produce high voltage like a long arc condition.

I don't know what the resistance of the cell is either. That's an interesting thought about the voltage, though. I was thinking that, if the welder was set on 5 amps, the duty cycle would effectively be 100%, and there would be no big deal at leaving it to go. I'm not an expert on the topic at all, but my hunch would be that a transformer welder would be more tolerant of being asked to create a high-voltage situation than an inverter. My sense is that inverters like to run within relatively tight operating conditions, while transformers... well, as long as you don't burn them up, what's to break?