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John in Oly, WA

Electro-chemical etching

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I put together a little electro etcher. Tried it out on some mild steel (A36?) with electrolyte specified for carbon and mild steel. The results were less than I was hoping for. I was looking for a deep etch and then blackening after. I'm wondering why the etch wasn't deeper and it didn't blacken at all. Maybe my pad was too small for the size I was etching? Not enough current? My technique needs work? Or just expecting more from the process than is realistic?

Etcher.jpg

EtchAttempt.jpg

electro-etcher_circuit.pdf

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A36 isnt an alloy its a structural spec, so you just told us that you used mystery metal and wonder why the etch didnt work right, correct?

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I never got great results with mine.  Note that I've only used it to mark 300 series stainless so YMMV.

I found that I needed to keep things a bit more "wet" to get consistent etching...and one part would work very well while the next had problems.  That was mostly due to poor masking but as you go deeper, fine details tend to get blurred. I found the "black" to be less than robust...rubbing removes it pretty easily.  If I was doing cosmetic stuff rather than just simple marking, I'd find a way to blacken other than simply the etch.

Not much else I can say except your mask tends to be the weak point on these.  I'd focus on tests with something simple--even just a "dot" and  you'll find the right tweaks for the etch itself.  Then you can move on to a more complex mask and work that whole new set of bugs out...

 

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No, not exactly correct Steve. I said mild steel, with A36 as a question mark only because some posters on IFI have said that it's possible when people buy mild steel, they may get A36. But what I could find about A36 designation, is it might have some manganese along with the low carbon and some minor amounts of phosphorous, sulphur or silicon. But, then mild steel can have manganese in it's composition as well, so either way, it's mild steel. When I bought it, I asked for mild steel. Is mild steel a mystery metal? Then I mentioned I used an electrolyte designated for carbon and mild steel, which is most likely appropriate for the application. I don't think that's where the problem is.

My focus is on the process, technique, amperage, maybe the circuit design itself. Thanks for relating your experience Kozzy. My investigations confirm your experience that it has to be wetter than I was keeping it. It needs to pulse the current (didn't build that in to the circuit unless the rectifier in converting the AC causes the DC to pulse), so lifting the pad every 3 seconds helps. And don't press the pad down as hard as I was doing.

I'll continue experimenting with it.

 

 

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Gee, I thought that etch looked pretty good.  I've always wanted to try to make an etcher but it's one of those projects I've put off.  

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No, Steve's right, unless you specify 1018 and pay the big bucks for it you're getting A 36. More reliable than rebar but it's made to minimum performance specs not analysis. So long as it's at least x tensil, x yield, x modulus, xetc. they don't care a lot what's in it.

Try etching something known say razor blades or buy something.

Wait till you play with electro polishing SS steel. You can get some really cool effects.

Frosty The Lucky.

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So mild steel IS a mystery metal? I will keep that in mind. My apologies Steve. I just figured I had mild steel and using an electrolyte for mild steel, then that wouldn't be where the problem was. I have some 1095 and 1084. The electrolyte specifies it's for high carbon and mild steel. So I'll continue the experimenting with that.

MC - I was just looking for a bit deeper etch and then the blackening effect after.

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A-36 has much looser controls for "tramp elements" as long as it passes the performance spec.  Lots of experience here with folks finding that their A-36 hardened when put in the slack tub, was weird trying to forge weld, was not uniform in working characteristics from piece to piece etc.  Of course the cheaper the steel generally the lesser the quality. (I've been told that Nuclear power plant rebar has very tightly controlled quality; otoh random construction rebar can be quite junky---read the articles about the radioactive rebar that came from down my way! Included cobalt from a medical device that was sold as scrap and only discovered when a truck went in the out gate at Los Alamos and the radiation detectors went off.)

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It's generally being applied wrongly to A-36 in my opinion; but it's more like asking for a 4 wheel drive car when what you actually want is a Range Rover.  The term mild steel is not specific to a particular alloy and as seen often applied to A-36 these days instead of the traditional 1020 and 1018...

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