Slashdot Mirror
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.
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.
The coolest voice ever.
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.)
Now, instead of merely cutting myself, I can electrocute myself as well. I love case modding!
Let's see your fancy "salt water" and "electricity" do this!
http://trigeek.net/mirror/etch/guides.php.html
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 :)
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.
Yeesh, you would have thought the kid would atleast have worn long sleaves and a face mask (welding mask)... They did this on Mythbusters and the fragments when into the human flesh like gel about 2inches...
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.
Let me introduce you to mirrordor.
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.
>>Let me introduce you to mirrordor.
The Mirrordoor? Is it like the door where you see your self coming into? It only managed to cache the introduction page of the website.
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?
This technology is nothing new. My father built systems to do R&D and production using Electro Chemical Machining. [...]
Items used every day may have under gone this process, turbine fan blades, air bag explosive chambers, hard drive motors (meow), test sabot rounds for tanks.
Are you sure those are all built by electrochemical machining? I suspect some of them are built by its close relative: electrodynamic machining.
Electrochemical machining is reverse electroplating. It pulls metal atoms out, not just from the cut, but from the surrounding metal that is intended to remain, changing its properites.
Electrodynamic machining is a spark to the workpiece through a dilectric solution (typically water or oil). It can cut through anything that can be made to conduct. (You do diamonds by flashing a bit of metal over them for the initial contact. As you're removing diamond, the surface that's left has a microscopic layer that is converted to graphite to keep you going.)
Three sorts of tools:
- Use the end of a wire as a drill. (Feed the wire as the end erodes.)
- Use the side of a wire as a bandsaw. (Feed the wire in the inches-per-minute range so the cutting edge is always smooth and of a known size.)
- Make a graphite electrode in the shape of the hole you want and burn your way in. (Graphite doesn't erode much at all. Replace as needed.)
Cutting action: The spark vaporizes a path through the dilectric and melts a tiny pit in the workpiece. (Polarity is chosen so most of the melting is on the workpiece.) When the spark stops the channel collapses and the shockwave blasts the molten material out of the pit before it can re-harden. Repeat at a rate in the kilohertz range. Spark generally forms at the shortest space, which is where you want to remove the most metal, giving you a mirror finish.
(This effect was originally discovered in Russia about WW II when an engineer tried increasing the life of ignition "points" by putting them in an oil bath to cool them. They disintegrated within hours. It's also why you always use a brush to run current around a lubricated ball- or roller-bearing instead of passing it through the bearing: The effect would destroy the bearing surfaces in a similarly short time.)
The cut-away material ends up as a contaminant in the dilectric. So you pump that through a filter to clean it out.
Motion control is paramount: You sense the spark voltage to tell how far you are from the workpiece and use it for feedback, advancing or backing up to keep your spark path at the correct length.
Contaminants (especially chips) sometimes short the gap, so you back out until you clear it and can spark again. Sometimes you end up machining away the chip. Sometimes you may have to back far - even completely - out of a cut to clear the contaminant from your gap. This may mean retracing your path around several turns. (In the shaped-carbon-rod drill-in mode you also run the rod in little circles and/or back-and-forth it now and then to pump the dirty dilectric out and clean stuff in.)
You're CONSTANTLY backing-and forthing. MOST of your tool motion is back-and-forth, a small fraction is motion into the workpiece as the cut advances. So you MUST use an integer motion-control algorithm that retraces its steps exactly (or within an LSB or so) and doesn't accumulate roundoff err. Any accumulated roundoff, even a TINY bit, quickly walks you out of your path and into the workpiece, shutting you down.
The device is essentially a big power supply, a resistor, a switch, a voltage measurement peripheral, a computer, a motion table, and a dilectric pump/filter. Most of the energy ends up in the resistor. You do it that way as the easy way to control the spark's waveshape. The switch might be a bunch of paralleled FETs on a big heatsink. The resistor might be a bunch of foot-long power resistors, with a fan blowing on them so you can run them far beyond their normal ratings, carefully wired to minimize parasitic inductance.
That's the bulk of the specialized knowlege you'd need to build one, as they were about 15-20 years ago (when I did software for one).
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way