Logo Etching Problems

OK, lets get a few things worked out.
The amperage rating of any component is the amount of current it will carry before burning up. This has nothing to do with the actual current in a circuit.

If measuring the DC current, you have to have the polarity right and have the ammeter in series in the circuit. In AC, you don't need to worry about polarity, but the ammeter still needs to be in series with the circuit.
The voltage and resistance in the circuit will determine the current. I=E/R .... Raise the voltage and raise the current. Lower the resistance and raise the current.

In an etcher, the circuit is from one lead, through the blade, through the electrolyte, through the pad, through the metal, and back to the other lead. It does not matter if it is AC or DC.
The things that can be eliminated as variables for the current draw are the wires, the transformer, and the bridge rectifier if in the DC mode. These are passive components if of sufficient rating, will not affect the current.
The size of the stencil determines how much of the blade is in the circuit, and will affect the current that passes through it, but that is a minor concern, as the actual exposed surface in an etch is very small..
The pad and its metal component are an issue, and the electrolyte is a big issue. While Zaph loves his paper core Q-tips, a piece of felt over a carbon block will work much better. Other things covered with felt, like brass, titanium, stainless steel, etc. can be the electrode, but whatever it is has to carry the current without any resistance. A carbon block with about 1 Sq.In. surface has a much better path for the current than the small amount of current a wet paper tube with a tiny surface area will allow.
Personally, I would change your etcher to a carbon block before I went farther, but for the purpose of this discussion, lets assume that a paper core Q-tip will work reasonably OK.

The etch is made in the DC mode when the current passes from the blade, which acts as the positive electrode ( anode) and passes through the electrolyte to the pad block, which acts as the negative electrode ( cathode). It take some metallic ions from the blade and leaves a shallow hole where they came from. The metal ions go through the electrolyte along the current path, and get deposited on the pad surface. In the AC mode it goes back and forth 60 times a second, leaving black metallic oxides in the hole left in the blade. This is caused by the metal (iron) ions combining with the electrolyte's ions, usually the chlorides and sulfides. If all goes right the "hole" in the blade is the exact shape as the stencil, and the black oxides make it a dark image.

That leaves the electrolyte as a suspected culprit. Distilled water has no ions in it to transfer the electrons from one electrode ( the blade) to the other ( the pad). Distilled water will not carry any current at all, because it has infinite resistance. Don't try this at home, but if you grabbed a 1000V line in one hand and stuck the other wire in a glass pan of distilled water, then stuck your other hand in the pan.....nothing would happen.
You have to add something to the water that give lots of ions for the current to go through. Salt will work. There are better commercial solutions, but a saturated salt solution will work fine. Make this by dissolving plain salt in warm water until it won't dissolve any more. Pour off the liquid to a clean glass or plastic bottle and use this as the electrolyte. If the electrolyte resists the current too much, as would be a low salt content electrolyte, it will not carry much current. If it has low resistance, the current will pass through it, bringing along the metal from the blade and making a etch where the metal was stripped out. The distance the pad is from the metal also affects the amount of transfer current. The pad should put the anode and cathode as close together as possible, with nothing but the electrolyte and the barrier ( the stencil) between them. The greater the distance between the anode and cathode the higher the resistance .... and the lower the current. That is one reason why I don't like Q-tips. A piece of damp felt on a flat carbon block is about the best delivery system you can ask for. Another reason the Q-tip is problematic is it only works with lots of electrolyte to keep it wet. If it isn't wet, it does not carry the current efficiently. Too much electrolyte makes for a blurry etch.

Your comments about destroying the stencil, and the pad getting hot make me think that one or both of two things is happening.
Either the pad is not keeping the two electrodes far enough apart and there is too great of current flow. The felt pad on a carbon block provides just the right amount of separation.
Or, there is far too much electrolyte in the path and it is allowing too much current to flow.
The only other variable is the stencil size, and I am assuming it is a normal size makers mark name/logo.

Photo posting is covered in many places...one is here:
http://www.bladeforums.com/forums/showthread.php/1088317-Posting-photos
 
If it were me, and it is not, I would re-trace every input and output connection starting with the 120V input, through the transformer, bridge rectifier, and all switches in the circuit. You don't burn a stencil in two or three seconds with a 12/24 volt transformer. Something just ain't wired right. (kind of like me)
 
You all are really patient. I generally am quite good mechanically but electrically I, uh,...follow instructions. Bladesmith's, thanks for the detailed explanation. From what I understand, more than one layer of felt would serve to keep the electrodes farther apart. Where can I find a carbon block. Would a brush from an electric motor work?

I am going to put it all back together tomorrow and recheck my assembly from start to finish. I understand how to measure amp draw fairly well...years back I built my own kilns and electric furnaces for my glass work but I just can't get my head around the disparity between the input and output sides of the transformer, amp wise.

Zaph1, that is a very generous offer but I sincerely HOPE I don't have to take you up on it.

If any of you ever make it to Cocoa Beach, cheeseburgers and drinks of your choice are on me!
 
Not a big deal to work on it. I've built around 80 etchers now and am getting rather good at it and have all the spare parts to make another 10 units. I've worked on a couple personalizers and they aren't dissimilar enough to be problematic to work on.
 
I looked over the schematic and shopping list on LoGuidice Custom Knives. His list called for a 200volt 6A bridge rectifier while the schematic noted a 400v 8A rectifier which is what I have installed. Would that be a problem? Other than that I picked up a graphite electric motor brush today and put 3 layers of felt on it, reduced the voltage to 7.5 and still wasted a new stencil in 2 etches so I have sent 2 wasted stencils and 1 new one back to Ernie to see what he says.
 
Fellhoelter said:
Dude, use store bought electrotlye.

It's almost free.
Click to expand...

Yup, good electrolyte is definitely the way to go, however I still don't think that is his problem. A conductor (electrolyte) conducts well or not so well. Regardless of the electrolyte, it in itself will do nothing to burn stencils.

There is something between the 120VAC input and the end output that is wrong. I still suspect a wiring/switch problem either through the transformer input and output or, through the rectifier wiring.
 
I have electrolyte on order. I'm walking away until I get some fresh stencils. I'll look at the wiring one more time. The 7.5v etch provided no appreciable heat and still wasted the stencil. My first and foremost problem in I am working in the dark. I have never seen one of these machines first hand.
 
Last edited:
This definitely needs pictures and preferably videos
No way your etchant or stencils are to blame
 
Rectifier size doesn't really matter. 400V or 200V are both adequate to handle 120V in the US, but it you moved to Germany you'd want the 400V to cover the 220v mains. You want to e-mail me some pictures and I'll look at them? charles@iowarepair.com
 
Well, where do I start. I mailed a couple of wasted stencils and one unused one to Ernie yesterday. He looked at the wasted stencils and determined that I had the polarity reversed on my DC jacks. When I wired this thing up I was sure that the DC positive should go to the red jack. The volt meter is positive on the red jack. When I tested the voltage in this configuration it LOOKED right (to me). I was sure I was going in the right direction because I was able to get a mark on the steel, just not a deep or crisp one. I had asked him about this when it first occurred but I guess he had to see the stencils to understand. I still don't understand why the red terminal is negative. But I'll take it.

So...I stated from the start that I was probably doing something wrong. I said that I might be thick in the head. Both of these are true. Apparently the etcher is now working properly. The stencils from Ernie were fine and salt water does work as an electrolyte (tho I do have some professional electrolyte coming in the mail). So until further notice, please don't call me glassguy. Please call me onedumbbunny. I'll let you know when to call me glassguy again.
Thanks to all who replied. The cheeseburger offer is an open ended invitation.
 
Don't feel bad. I can make and do many things but I never got around to learning that new fangled electricity thing. That is why I bought an etcher and why I run pulleys on my grinder. If something goes out electronically... I am in trouble.

As for the electrolyte coming you will be thrilled with the improvement over the salt mixture.
 
bladsmth said:
In an etcher, the circuit is from one lead, through the blade, through the electrolyte, through the pad, through the metal, and back to the other lead. It does not matter if it is AC or DC. (It matters in DC).................

.................The etch is made in the DC mode when the current passes from the blade, which acts as the positive electrode ( anode) and passes through the electrolyte to the pad block, which acts as the negative electrode ( cathode). In the AC mode it goes back and forth 60 times a second, leaving black metallic oxides in the hole left in the blade.
Click to expand...

While Stacy and I don't always agree on some things, he nailed it here.

Glad you figured it out.

Robert
 
Glad to hear you have the problem solved, that is all that matters. All the comments here talked me in to getting some professional electrolyte too. So you may have helped many other people in different ways. :thumbup:
 
And that's why all of the posted schematics suck!

Red as negative... Bass Ackwards if you ask me...

I should post up one I drew a while back, it has all of the colors matching industry standards.
 
glassguy said:
Well, where do I start. I mailed a couple of wasted stencils and one unused one to Ernie yesterday. He looked at the wasted stencils and determined that I had the polarity reversed on my DC jacks. When I wired this thing up I was sure that the DC positive should go to the red jack. The volt meter is positive on the red jack. When I tested the voltage in this configuration it LOOKED right (to me). I was sure I was going in the right direction because I was able to get a mark on the steel, just not a deep or crisp one. I had asked him about this when it first occurred but I guess he had to see the stencils to understand.

I still don't understand why the red terminal is negative. But I'll take it.

So...I stated from the start that I was probably doing something wrong. I said that I might be thick in the head. Both of these are true. Apparently the etcher is now working properly. The stencils from Ernie were fine and salt water does work as an electrolyte (tho I do have some professional electrolyte coming in the mail). So until further notice, please don't call me glassguy. Please call me onedumbbunny. I'll let you know when to call me glassguy again.
Thanks to all who replied. The cheeseburger offer is an open ended invitation.
Click to expand...

That confused me on all the plans diy too.

The pro manufactured ones also do it that way


The best reasoning I have found is that they call the electrodes the hand-piece and the grounding plate.
Having the polarity backwards keeps black to the grounding plate, so it's like a car black ground - as long as you ignore the real polarity.
 
Glad it got worked out.

Robert, My first comment was on identifying the circuit and the amperage. A you pointed out, to get a proper etch in the DC mode, the current must run in a certain direction.

In engineering terms, this is called the stripping mode. The reverse is the plating mode. Many plating machines and things like etchers use the term "work" to label which lead goes to the knife or item being worked on. This is because the current runs in different directions depending on what function is being performed. Sometimes the work is positive, and sometimes it is negative. I agree that red/black colors can get confusing. Mostly, they are just to identify which lead goes where. I would be happier with green and yellow or something like that on many pieces of equipment. The reason red and black are used is because premade leads are readily available cheaply in red/black.
 
Fellhoelter said:
And that's why all of the posted schematics suck!
Red as negative... Bass Ackwards if you ask me...
Click to expand...

So. . . . The polarity of my etcher is opposite that of other etchers?

Red to the knife, black to the pad/q-tip. That's the way my etchers ship and that's what is written in the directions included with them. I thought that all etchers were that way. I guess not. Only a fool would ever make red negative and black positive. As far as off color leads, green and yellow leads are about the same price. The issue would be finding green/yellow jacks.
 
You must log in or register to reply here.
Back
Top