Electrolytic Etching, For What A Dremel Can't Do

Dustin writes "A lot of people modify computer cases, often requiring them to cut intricate custom designs in sheet metal. For most, there is the Dremel tool. But sometimes, that just isn't good enough. Possibly due to an insanely complex design, or unsteady hands, a Dremel just might not cut it (pun honestly wasn't intended). JimBob, a member at OverhauledPC.com, has a much better way. Using readily available salt water and electricity, his technique is much easier than trying to cut patterns with a rotary tool."

Comments

Coral Cache, just in case...

[BobPaul]

I preloaded this into the Coral Cache, just in case it gets slashdotted.

Here's the Cache Link if it's needed.

mirror

[Wakkow]

http://trigeek.net/mirror/etch/guides.php.html

To summarize...

[syukton]

I'll try to summarize this since I managed to read the first few pages before the horde of slashdot ate the website.

You take two plates of metal and hold them parallel (not with your hands, they're going to be electrified!) underwater. Electrify the plates and the positive ions in the water will collect at the negative terminal and the negative ions will collect at the positive terminal. By adding some salt to the water however, you can encourage a chemical reaction to happen at a given electrode. By covering the metal with paint or duct tape, you insulate it from this effect. So what they're doing is, essentially, painting around the hole they want to cut, leaving the hole itself barren, then submerging it in saltwater and electrifying it, causing the exposed metal to oxidize and be eaten away.

It's roughly the opposite of electroplating, which is the procedure which this technique is likened to in the article. Instead of trying to accumulate more on a given electrode you're trying to reduce the amount of matter present there.

Re:To summarize...

[Vellmont]

By adding some salt to the water however, you can encourage a chemical reaction to happen at a given electrode.


No, the salt is to reduce the electrical resistance of the water and create a greater current flow. Pure water actually has a high amount of electrical resistance. Oxygen will collect at the positive electrode, and hydrogen will collect at the negative (the article author is a bit confused and thinks this is methane).

You're correct about the rest of your summary though.

Can also be done in a much simpler...

[Lisandro]

...(and safer) way with FeCl3 (ferric clhoride), the very same stuff used to etch circuit boards by hobbyists arround the world. Since it attacks most metals, you can do complex chemical etching with it: i've seen small plates with logos done that way - you just have to find a way to mask the design somehow. It requieres no electricity as well.

FeCl3 is cheap, relatively safe (don't eat it kids!), and easy to handle. It stains like a bitch though, and will attack most metals so be careful with spills.

I used to do that with nitric acid

[museumpeace]

Works on brass too. but its harder to get ahold of that stuff nowadays. Drano will probably work faster on Aluminum and not require electricity but you got to play with the concentrations or the process will heat up so fast it will melt your resist.

Re:Wait a minute.

[Aglassis]

You said: "I encourage you to try it without the sodium... chlorine ions are, shall we say, not very good for you. Salt may dissociate in water, but it's safe there in equal quantities. Surprising that something so bad for you doesn't violate sanjimon(?)'s principle."

And chlorine isn't good for the metal either. If you are interested in preserving the mechanical properties (especially the surface properties), using chlorine in an electrolytic metal removal process is a bad idea (in general, any electrolytical metal removal process will contaminate the remaining surface). Many bad types of corrosion are started with just a little bit of chlorine. Do a google search for chloride stress corrosion cracking for one of the very worst types of corrosion known.

Anyone interested in using electrolytic metal removal for any project that is under high temperature and stress (a case mod *probably* won't qualify) should definately not use the NaCl procedure. In fact, if you ever want to do a project under high temperature and stress you need to carefully monitor the exposure of chlorine, oxygen, hydrogen, and sulfur ions (to name a few) as well as things like the pH to ensure that your piping doesn't fail.