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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."
I preloaded this into the Coral Cache, just in case it gets slashdotted.
Here's the Cache Link if it's needed.
http://mirrordot.org/stories/a78b5e9e7316f6c5e22cb 6e6b30c43a3/index.htmlMirrordot link here/URL
got sig?
http://trigeek.net/mirror/etch/guides.php.html
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.
Reinvent the wheel only at either a lower cost, greater effectiveness, or your own personal enrichment and satisfaction.
how do you produce methane from NaCL, H2O, and Fe ???? I think only H2, and O2 are emitted!!
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.
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.
SLASHDOT: news for people who can't concentrate on work or have no life at all and got tired of yelling back at the TV.
Not directly dioxins, but it does make covalent chlorine, which often ends stabilizing as dioxins. Even if it ain't that, its still BAD (worse than not putting comments in code, Broken As Designed).
Unfortunately, I was unable to load the article - so I can't comment on the procedure involved. But if you haven't studied electrochemistry to at least a small extent to know whats going on (and I know people with B.S. in chemistry I wouldn't trust with understanding reactions in this catagory), its best you DO NOT try this. The procedure listed may be completely harmless, I can't say without having access to reading the procedure. But if you are someone (like most slashdotters) who doesn't hesitate at "improvising", stick to the dremel.
Easily done. Head to Techniks or some other similar place and get some Press 'n Peel PCB transfer film.
Draw what you want to etch as a negative and then iron it onto your metal. Dip the whole thing in the acid bath and wait a bit. Steel wool to clean off the resist and that should do it.
If you're really cheap, toner is a decent resist. No different than making a homebrew PCB.
Weaselmancer
rediculous.
I managed to grab a link out of the page from mirrordot before it went tits-up again. This is the link the guy got part of his idea from.
http://gravert.club.fr/galvetch/contfram.htm
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Back when I sold tools, what Dremel was particularly good at was convincing people to move up to Foredom. :)
I doubt we would sold a tenth as many without those little plastic toys suckering people in. Thanks, Dremel!
Roughly speaking, you don't use acid because you would need too much of it, and it sucks at cutting, and at giving neat edges. Oh, and resists are difficult, and it's slow.
Resists: You need something that is resistant to the acid, but can be applied neatly, and removed neatly afterwords. It needs to adhere well to the metal surface, yet be resistant to the acid and to water, and any by-product produced. Also, it needs to be resistant to exfoliation - as you start to etch, it's no good if your resist falls off around the cut. Oh, and it needs to be cheap and easily available.
Rates: Acid is slow. Or, rather, acid's that you would want to use for this purpose are slow. Anything that can eat through steel or aluminum at a decent rate is not something you want to handle. (Consider: What do you store it in, and what do you do the reaction in? Both are doable - but not strightforward). So you're left with acids that don't eat the metal very fast.
Edges: With an electrical current, you can ensure that the direction of cutting is more or less perpindicular to the surface of the metal (that's why it's two large plates, for example). With an acid, that's not the case. They will tend to etch out round indentations under the edges of the resist - giving you razor sharp edges to your cut out. Which would need filed down afterwords, and means there is a minium thickess of cut, proprtional to the thickness of the sheet.
My back of envelope sums suggest that the miniumum width of cut by acid etch is roughly equal to the thickness of the material, assuming an infitessimally small start. For 1.2 mm sheet metal, that's a 1.2 mm width - easily doable with a Dremel.
It would also take around 3-4 months, I think.
Acids are good at etching a surface layer. I would use an acid if I wanted a matt surface - for example, to etch details onto sheet metal. A combination of cut outs and etching would work very well in giving a unique appearence to a panel.
In theory this MIGHT be possible. In reality a 50W CO2 laser WILL NOT cut sheet metal. A quote from this site "Metal Cutting is "Not" possible, however the system does a fine job of "Etching" Anodized Aluminum" and they are talking about a 50W laser. While my 35W can make a piece of ceramic tile glow red/orange where the laser hits it, it will not even make a mark on steel.
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.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
Using salt for this will produce chlorine in addition to oxygen.
Use baking soda or sodium hydroxide instead. Either electrolyte will give off substantially less-dangerous byproducts.
p
In Korea, long hair is for old people!
The 40% solution mentioned in the article probably limits the strength.
Keep it off of your 501's or we will know you can't use a Dremel tool.
From: Electrochlor.com
1.2 Reactions
The principle reactions occurring in the electrolytic cell that produces sodium hypochlorite are quite simple, as shown in the following:
Oxidation of the chloride ion occurs at the anode:
2Cl- -> 2Cl2 + 2e-
Followed by a rapid hydrolysis of the chlorine:
Cl2 + H2O -> HOCl + HCl
Reduction of the sodium ion occurs at the cathode:
Na+ + e- -> Na
Followed by a rapid reaction of the sodium with water:
Na+ + H2O -> 1/2H2 + NaOH
The acids (HCl and HOCL) produced at the anode react with the base (NaOH) produced at the cathode:
HCl + NaOH -> NaCl + H2O and,
HOCl + NaOH -> NaOCl + H2O
The net reaction of electrolysis is:
NaCl + H2Oe- -> NaOCl + H2
The amount of hypochlorite produced is related directly to the amount of direct electrical current passed through the cell.
Easier to read on web site. I had to hack in '->'s.