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Hardware Hacking

Electrolytic Etching, For What A Dremel Can't Do 242

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, 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."
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Electrolytic Etching, For What A Dremel Can't Do

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  • by BobPaul ( 710574 ) * on Monday January 31, 2005 @08:56PM (#11535387) Journal
    I preloaded this into the Coral Cache, just in case it gets slashdotted.

    Here's the Cache Link [] if it's needed.
  • by Anonymous Coward
    Or maybe someone used one in the server network cable... no comments and down.
  • by Faust7 ( 314817 ) on Monday January 31, 2005 @09:00PM (#11535421) Homepage
    Using readily available salt water and electricity, his technique is much easier than trying to cut patterns with a rotary tool.

    The site is down. Therefore I will assume that he poured water over the case and shocked the shit out of it.

    You could get some interesting burn patterns that way. You might even match your case.
  • by gambit3 ( 463693 ) on Monday January 31, 2005 @09:00PM (#11535422) Homepage Journal
    any of the paying Slashdotters wanna grace us with the text?

    I promise you'll get lots of Karma for it! ;)
  • by Tackhead ( 54550 ) on Monday January 31, 2005 @09:00PM (#11535424)
    > Electrolytic Etching, For What A Dremel Cant Do

    First off, there's nothing a Dremel can't do.

    But since your alternative involves electricity, water, and chemicals, we'll forgive it. (But next time, could you kindly use something more dangerous than sodium chloride? We've got reputations to uphold here, and if the case mod weren't so danged cool, we'd feel we were slipping.)

    • by Ann Elk ( 668880 ) on Monday January 31, 2005 @09:05PM (#11535470)

      Try it without the chloride.

      • by kryogen1x ( 838672 ) on Monday January 31, 2005 @09:39PM (#11535739)
        Try it without the chloride.

        That, or NaCl sans sodium. Gotta love those chlorine fumes.

      • 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.
        • Chlorine isn't good for you, but Sodium metal and water are a lot worse. BOOM.
        • Re:Wait a minute. (Score:3, Informative)

          by Aglassis ( 10161 )
          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 electrolyt
          • Re:Wait a minute. (Score:3, Interesting)

            by WhiteDragon ( 4556 )
            I can verify first hand the corrosive power of chlorine. When the US Postal Service was anthraxed, we cleaned out the Trenton New Jersey Processing and Distribution Center with Chlorine gas. It killed the anthrax, but just about all the mail processing equipment had some damage due to corrosion, and a great deal of it was so corroded that it was a total loss.
    • by Tumbleweed ( 3706 ) * on Monday January 31, 2005 @09:09PM (#11535503)
      there's nothing a Dremel can't do

      Welll, let's be fair, here, there _are_ some things that a Dremel can't do. But that's what duct tape and/or WD-40 are for!
    • We've got reputations to uphold here...

      There's always hydrofluoric acid for etching true glass side panel insets (cover the entire glass with a thin layer of candle wax, scrape away the wax cleanly from areas you want eteched, wash away the acid carefully, melt/scrape away the remaining wax). Here's at least one site [] with more info.

      Of course all the appropriate warnings apply as to the caustic nature of acids, fumes, potential for damage to clothes, skin, etc... Oh, and don't try this on plastic/metal

    • But since your alternative involves electricity, water, and chemicals
      Commercially available machines use kerosene as the liquid. This method is good for cutting through really hard stuff - eg. tool steel or alloys used in hard rock mining.
    • Hehe, this guy is really talented. He disguised the stuff :)
      Sodium chloride is just to allow the current flow. The real power is Water!
      Oxygen does the cutting. Hydrogen gets emitted into the air, mixing with air oxygen, creating high explosive in your room :)

      Enough for "reputation to uphold"?
    • Can a Dremel hammer in a nail?
  • by Gorffy ( 763399 ) on Monday January 31, 2005 @09:00PM (#11535427) Journal
    Now, instead of merely cutting myself, I can electrocute myself as well. I love case modding!
  • by Ghostgate ( 800445 ) on Monday January 31, 2005 @09:01PM (#11535439)
    Let's see your fancy "salt water" and "electricity" do this! []
  • mirror (Score:5, Informative)

    by Wakkow ( 52585 ) * on Monday January 31, 2005 @09:04PM (#11535464) Homepage
  • by AC-x ( 735297 ) on Monday January 31, 2005 @09:06PM (#11535478)
    What a true geek would do is build their own computer-controlled laser cutting/etching rig, a few of these [] together should cut through aluminium or mild steel no problem :)
  • To summarize... (Score:5, Informative)

    by syukton ( 256348 ) * on Monday January 31, 2005 @09:09PM (#11535500)
    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... (Score:5, Informative)

      by Vellmont ( 569020 ) on Monday January 31, 2005 @10:15PM (#11535986) Homepage

      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.
      • Re:To summarize... (Score:2, Informative)

        by MConlon ( 246624 )
        Actually, you're going to get hydrogen and chlorine at the electrodes and be left with a solution of sodium hydroxide.

        Chlorine gas is poisonous. Fortunately it's heavier than air so it shouldn't fill the room or anything. Sodium hydroxide is caustic.

      • The O2 will not come off as gas, but will react with the Na+ and Cl- to form NaOCl in water (Bleach).

        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: []

        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

  • methane gas???? (Score:2, Informative)

    by Anonymous Coward
    how do you produce methane from NaCL, H2O, and Fe ???? I think only H2, and O2 are emitted!!

    • There's carbon in steel.
      • There's carbon in steel.

        A typical alloy used in sheet steel is known as "1020", which has an average carbon composition of 0.2%. If you get methane there will not be much, even if the formation of methane is favoured over hydrogen.

        You can buy machines that do this form of cutting which work in a kerosene bath. The kerosene evaporates (and also turns to black sludge on the bottom) so you have to take care that the arc doesn't happen at the surface of the liquid, or you could get a fire - which is probabl

    • The water will be electrolyzed into H2 and O2.

      2H20 -> 2H2 + O2

      You're not going to evolve methane (as the article says). Sheesh.
    • yup you're right - I used the slot car transformer in salt water technique to make H2 as a kid ... my mother made me stop because of the Cl2 that came off the other end (mostly disolved in the water - I'd guess he's making something like FeCl3/NaOH (in solution) - it probably turns a dirty yellow
    • Actually, O2 isn't emitted. Even before connecting into 2-atom particle, still as O- the extremely reactive ions oxidize the steel, providing a lot to the etching process.
      But H2 still goes up and likely boom.
  • One of my friends reminded me the other day of a time when he was making his cooling system. After a while of playing, his computer made wierd noises, and so by looking through the case window we could notice that his cooling system did not work. Basically it looked like a carwash inside his computer. I feel that the best case designs come from mistake, even though that mistake cost him his wonderful computer parts. But lego cases look cool too.
  • Isn't that how they make dioxins?
    • by Anonymous Coward
      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 D
    • Naw. Dioxin is formed when you incinerate PVC. When you're bic pen lands in the municipal trash burner, dioxin is made.

  • Dremel Casemod (Score:2, Interesting)

    by HighBit ( 689339 )
    Kinda apropos, dremel has a Case Modding Project [] on their website. They cut the word DREMEL into a case. Looks nifty.
    • Ok, so can someone explain to me why he cuts the middle of the D out and then cuts the outside as well? Seems to me he could have saved a step there...
  • Kirk: Spoooock!

    Scotty: He's dead already, Jim.
  • by Lisandro ( 799651 ) on Monday January 31, 2005 @09:29PM (#11535666)
    ...(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.
    • FeCL3 does, however, get depleted with usage. Munching through a 1-2 mm steel plate will require quite a bit of FeCL3.

      Anyone tried spark eroding?

    • All Ferric Chloride does is eat copper. To make a design, you still need to mask it somehow.

      Something as simple as a magic marker can be used, but it will probably look like ass. A better idea is to use a photo-resist kit. With this you spray the metal surface with a chemical that will protect it from the FeCl_3. The kicker is that light will eat away this protection. So you print your design onto an overhead transparency or something, place that atop the metal, and affix it to a window for a while

      • The two simplest ways i've found to transfer designs for FeCL3 etching were:

        1) Press-n-peel blue [], which is a sheet of material that will stick to a surface only where it's printed. It's hard for me to find it where i live, so what i use is...

        2) Laser printer and satin ("photo") paper. Laser printer toner is 100% waterproof and melts when heated; you print you design, mirrored, onto a satin paper sheet, then iron it over the metal (previously cleaned and degreased with alcohol), and carefully peel
      • All Ferric Chloride does is eat copper.

        No, it eats almost any metal. Maybe not gold, palladium, or platinum, but it has eaten any metal or alloy on which I tried it, including stainless steel.

    • just have to find a way to mask the design somehow

      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.

    • by Dan East ( 318230 ) on Monday January 31, 2005 @10:58PM (#11536290) Journal
      I've been using Staples Picture Paper to transfer the ink to PCBs (you have to print your mask with a laser printer - inkjet won't work). That particular brand of paper works extremely well, as determined by a fellow who tested dozens of types of glossy photo-quality printer paper to see what transferred toner the best.

      I don't see why this wouldn't work on cases. You use an iron to transfer the toner from the paper to the surface to be etched. Extremely narrow traces can be obtained ("MUCH less than 0.01 inches") with this method, so I'm sure it would give good results for case mods.

      This website has the detailed instructions: []

      Dan East
    • I disagree.

      Electrochemical reactions happen at extremely low voltages and in this case don't require any fancy reagents. You have the same masking problems with a chemical etch as with an electrochemical etch, but instead of needing a very average DC power supply, now you need something which you really shouldn't allow to touch your skin.

      For anyone thinking of using any corrosive to etch metal, look up its MSDS [] and make sure you know what you're doing. The same can be said of electrochemisty, but we'

      • Actually, FeCL3 is quite safe, even if it touches your skin. The thing is it that it stains skin like hell, never mind clothing.

        Thing is, when you do electrochemical etching you have two points of "fuckup": the power supply and the etchant itself :). FeCL3 is quite straightforward to use; some people like to heat it a bit in order to speed the etching process but i've found it works perfectly at room temperature. All you need it's a plastic container, plastic gloves and patience.
    • ...(and safer) way with FeCl3 (ferric clhoride), the very same stuff used to etch circuit boards by hobbyists arround the world.

      I have forgotten a lot of chemistry over the years. I thought Ferric Chloride works as an etchant for copper because the chlorine prefers copper to iron so it is happy to trade an iron atom for copper. But why would it trade an iron atom for another iron atom? Now in a solution, there will be free chlorine and iron ions floating about so the chlorine may etch the steel but I

      • You're right: FeCL3 is used as a solution (quite dilluted IIRC, i never was any good at chemistry) which makes it quite safe to handle. It's sold mostly in bottles, though i've seen places selling the raw stuff ready to be mixed with water.

        I've etched brass an copper with it, and seen it leave awful spill marks on aluminum; generally, if it's metal, it will react with it, to different degrees. The reaction is quite slow too, and to stop it you just need to dilute it badly with water. Then the solution
      • But why would it trade an iron atom for another iron atom?

        Because it turns from "ferric" to "ferrous". Ferric chloride is red, ferrous is green. Try this: dissolve enough iron in ferric chloride until the solution turns pale green. Then add caustic soda to it. This will cause the iron to precipitate as iron hidroxide, it's one of the most saturated red colors you can find.

    • ...(and safer) way with FeCl3 (ferric clhoride),

      That's just ordinary acid attack. The method described doesn't need masking and can cut through material. You can cut smooth holes in very hard materials with a slit copper tube as an electrode. If you keep the liquid flowing you get faster cutting (washes away the corrosion products).

      Ferric chloride etches copper very well, but for other materials you will want to use other stuff. Around 15 percent nitric acid in alcohol etches steel nicely and quickly

  • by museumpeace ( 735109 ) on Monday January 31, 2005 @09:33PM (#11535689) Journal
    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.
  • Bad guide (Score:3, Insightful)

    by s0rbix ( 629316 ) on Monday January 31, 2005 @09:38PM (#11535734)
    This is a terrible guide. Several times he says "make sure you know what you're doing" but offers no help or explanation. It is poorly worded and offers little guidance. The pictures do not help at all, either. Does anyone know of a better guide for electrolytic etching?
    • "Know what you're doing" == "CYA". Basically, paint the thing to be etched and cut with an exacto where you want the cuts. Create an electric current in a salt bath, and use the piece to be etched as the (negative or positive, I forget) electrode. Watch out for methane; not really that hazardous, just do it outside (or have proper ventilation - if you had it, you'd know it) and don't smoke around it.
      • No, this guy obviously has no idea what he's doing.
        He is releasing cupious amounts of HYDROGEN gas.

        Iron plate: Fe
        Water: H2O
        Salt: NaCl

        Methane: CH4 HOW?!?!?! No carbon involved!

        This is electrolysis. Splitting water into O- which oxidates the metal (cutting it) and H2 which floats to the surface, gradually filling the room till everything goes Kaboom.

        Know what you're doing. Definitely.
  • Instead of all of this electricity, etc. why not use plain old acid? (Like from a car battery or something). Maybe even H2SO4 or HCl from a hobby store.
    • Re:Acid? (Score:3, Informative)

      by DarkMan ( 32280 )
      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 fa
    • H2SO4 -- sulfuric acid.
      see also, battery acid.
      HCl ---- hydrochloric acid
      see also, component of stomach acid.

      I don't know what part of the world the parent
      poster is from, but these items are not likely
      to be available from any USA "hobby shop" I
      have seen. In the USA, either a chemical
      supply house or else a friendly local electro-
      plating company might be better choices.

      However, it should be cautioned that acids
      (especially concentrated acids) are quite
      dangerous. Protective gear (heavy ne
  • by RiffRafff ( 234408 ) on Monday January 31, 2005 @10:48PM (#11536204) Homepage
    Cover the "canvas" with masking tape. Draw your design. Cut out your design with a sharp X-Acto blade. Etch the exposed design with a bead-blaster (like a sand-blaster, but uses smaller, more uniform glass beads, and doesn't eat away as much, as fast).

    Been doing this for years.
  • 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.
  • The server was down before I could read the whole article, but it sounds like the same technique many amateur pulsejet builders use to manufacture their reed valves.
  • There is a coil pattern etched into the case after the network cable sitting there vaporized.
  • All that's left is to grab a dremel and grinding bit to smooth up the edges, as the process is not perfect. Here you can see that one of the sides is almost completely smooth while the other is a tad rough, but still overall a good effect.

    If you look at the pictures, you will notice the edge is not perfect and indeed there are problems with using this method for intricate designs. Especially if you use duct tape as your insulator like this guy did. You could cut your design labor down considerably by us

  • Salt = Bad (Score:3, Informative)

    by the pickle ( 261584 ) on Tuesday February 01, 2005 @02:05AM (#11537480) Homepage
    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.

  • At least three of today's headlines have punctuation or grammatical errors: "Electrolytic Etching, For What A Dremel Cant Do", "Bill Gates Handwriting Analyzed", "ATI at the Top Graphics Chip Maker for 2004".
  • by sakusha ( 441986 ) on Tuesday February 01, 2005 @03:33AM (#11537886)
    A REAL geek would use Explosive Forming. []
  • I'm looking, and while this is very neat, I don't see it getting results superior to those you'll be getting with a dremel that has a depth gauge, a spin saw set for metal, and a set of router bits.

    This is also pretty labour intensive, you have to completely paint the area you don't want destroyed first, then you can destroy the non-painted area, then you'll probabally have to refinish the edges on anything really complex like a spider design, or text, because in the pictures the cut lines are pretty rag
  • I had to hack out a large chunk of an old Gateway case to fit a new motherboard. It took a very, very long time to do with an angle-grinder bit and covered every surface nearby in black dust.

    Is there an easier way to do it with a dremel? What part number is best for this?

  • We have been doing this for years... Ever hear of making PC boards...

    Or how about valves for pulsejet engines..

    Using it on a PC case? Isnt that pretty much common sence?

    Sheesh.. Has the whole world 'gone dumb' or what..

    What is next "ooh, look the sun rises. Must be something to get exited about"

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