So, I have experimented with the kit components a bit and I am thinking I have a broader understanding of how to approach the project I initially had in mind. I've got a blind spot (maybe a few or a lot). I need to be able to pass a current through an electrolyte and be able to have dynamic control of the voltage/amperage in solution. Like, I want to be able to have a knob I can turn to set it from 1.5 to 3 volts. I also want to be able to set a timer where it cuts everything off when the cycle is complete. I am looking for advice on what components would most efficiently achieve these tasks. I am also interested if anyone knows of any projects I can do to help me better understand the solar unit and feedback to and from that unit. I'm in the process of doing research, so ya know. Just if off the top of your head, you have some thoughts or resources, they would be highly appreciated.
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Just read some of your comments. I’d recommend you focus on current rather than voltage. For etching/plating or anodising, required current is calculated by the surface area of the piece, and the voltage will fluctuate depending on the anodes you are using, their spacing, volume of electrolyte, type of electrolyte, and concentration. The voltage required to deliver the required current will change as the process progresses due to changes in temperature and conductivity of the electrolyte. As smut builds this increases resistance, along with it also collecting on the anodes. In both of these cases the voltage will need to increase to keep a steady current level. You would need to design a constant current power supply. I would be more inclined to purchase a power supply which offers this feature. Which metal are you etching? Isotopic etching can be achieved by different methods depending on the metal, though regardless of process it does have its limitations in terms of resolution, when compared to anisotropic etching.
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Looks like a simple solution which would not need an Arduino unless there are other parameters you haven't mentioned. As I understand it, you just need a variable voltage power supply for 1.5 to 3V DC at an unspecified current. Or do you need to set a fixed current which needs the voltage adjusted in that specified range. You also need a timer to switch everything off after an unspecified time. So all you appear to need is a variable voltage PSU and a mains timer.
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I need to be able to set the initial voltage between 1.5 and 3V and for that voltage to be the same in the electrolyte throughout the process. Yes for the rest of that.
And perhaps I have misunderstood, because I have zero engineering experience, but from what I understand, it's actually the resistance/voltage drop when it hits the electrolyte that matters. How much voltage you need depends on the size metal you are etching. So I guess the only way I know how to explain it, is I don't want to just dump 1.5 volts in the solution. I want to start at 1.5v and allow the unit to adjust for resistance?
Hah. Seems simple enough, but maybe I need to keep learning. And while it seems like I am reinventing the wheel, the process translated to metalsmithing has real issues.-
Thank you for taking the the time to clarify and provide so much information. That's exactly why I asked the question.
I know a bit of programming, a bit of the science behind etching, and very, very little about what is out there on the component side. Or how to make those two worlds connect. I appreciate your time!
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You don't actually need to measure the resistance as long as you know what you want the current to be. Power supplies are available that can provide a constant current as long as the load remains within their capabilities. So let's assume you need a constant current of 1amp and the nominal resistance of your electrolyte is one ohm. This will require the power supply to output one volt to pass a constant current of one amp. If the electrolyte resistance increases to two ohms, the constant current power supply will automatically raise the voltage to 2volts to compensate for the increased resistance. The actual power going into the electrolyte in Watts is equal to Volts x Amps. So as electrolyte resistance increases, the wattage increases in proportion. The power supply needs to be capable of providing the maximum wattage in the worst case situation where electrolyte resistance is at a maximum.
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Right. The quality of etching is affected by the speed of the flow, so current is what needs to be consistent, right? The resistance increases in the circuit at the electrolyte bath and surface area of the piece to be etched plays a roll in that, among other things. So as I understand it, I should be able to measure the resistance and adjust the voltage to keep the current consistent. Is this correct or am I missing something?
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The problem is, that voltage, current and resistance are inextricably linked by the formula V= I x R. So if you set the voltage to 1.5 volts, the current will depend entirely on resistance. You have not indicated how you want the automation to adjust for resistance. From what I remember of electroplating, the current controls the rate of ion transfer, but there is probably a relationship with the surface area of the item being played. In order to create an automated system, you need to be able to provide an exact definition of the required current as determined by factors such as electrode surface area and electrolyte concentration. Only then can you hope to create an automated system that can adjust plating conditions to the optimum throughout the plating cycle. The ability to automate processes relies on the ability to define all the parameters required over the entire operating range of the target device.
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what?
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It's a device used for electrolytic etching. There are already machines made for that, but you don't need the voltages for smaller projects in metalsmithing that you need to etch a printmaking plate. The ability to tweak the current improves the quality of the etch. Making it solar powered is just my preference. One of the things about etching, is it likes to rust any carbon steel in the area. I've got hammers, anvils, stakes, a hydraulic press, rolling mill, ect. I usually set up outside, away from all that. It's nice not to have to drag an extension cord across the yard.
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Arisha Sattler
When we were introduced to the process in college, they basically said - this is a rectifier. Red goes here, black goes there. Set it to no more than six volts and check frequently to see if it is done. But you're talking about people who are mostly doing photo etches, and they are not necessarily worried about imperfections. For them, it is part of the medium. As for me, I am over here with precise drawings and thin lines and my designs are getting blown out and I am having issues with patterning on the plate. And I don't think the imperfections are cute.
The plate below was one of the first satisfactory etches I got, using nothing more than a AA battery pack and salt water for about 80 minutes in a large pyrex beaker.
I think the only thing I haven't experimented with, as a basic unit, is temperature. And I am measuring values with a multimeter as I go. Previously, I was coming from the angle of treating the electrolyte bath as a component which needed better design. Then, becoming aware of other objects I can add to the environment, I am thinking it might be easier to control the other pieces on the board.
I had not heard the isotropic/ansiotropic bit. All I could find is information on plasma etching. Isotropic seems to apply to electrolyte etching and chemical etching, but I couldn't find any information on how ansiotropic would differ in those processes.
Thank you for the feedback. I appreciate you taking the time to leave me with some information and some things to think about.
Jai Dimas
Arisha Sattler
I watched the video. That's the cool thing about metalsmithing. There is more than one way to do things and as you said, you've found a way that gives you results you are satisfied with. I have, but do not use those products, for reasons other than performance. I am actually pretty confident in my process, so that really isn't a problem I am trying to solve. I am satisfied with the results I get. I'm just looking for a way to streamline the process I already have in place. I appreciate the suggestion and the link, though. I am going to dig a little deeper into the ansio/isotropic bit, which seems interesting. Thanks again!