Building an etcher and using electrochemical etching on a BK12

[granitestateofmind]

I built a new etcher out of a 12 volt DC power supply that I had lying around; it's made as an auxiliary power supply for the alarm industry. I did purchase a DPDT (double pole, double throw) ON-OFF-ON switch from a local electronics surplus store for a couple bucks. The important thing here is that while DC will etch steel, you need AC to blacken it. So...I used the switch to flip between the DC output from the board and the AC output of the transformer that feeds it. I mounted a duplex outlet inside the can and cut the end off a power cord for a computer power supply. I've got dozens of those things. You could also do this with any DC transformer (like for a cell phone or old computer power supply) and a doorbell (24VAC) transformer; a lot of this stuff is available pretty cheap or free if you have access to a "recycling center" (dump). The leads for the alligator clips are attached to the center terminals on the DPDT switch; DC leads (make sure to observe polarity) to one side of the switch; AC (polarity unimportant) to the other.





AC source and power for the DC board:



The DPDT switch. 2 center terminals are for the alligator clip leads; flipping the switch connects either the DC or AC power source to the leads:



Wired up; the transformer feeds the input terminals for the DC board and are also connected to one side of the DPDT switch via jumpers from the board. DC output from the board feeds the other side of the DPDT switch.



In the center position, the switch disconnects the leads from any power even when the unit is plugged in.



And here's the whole thing ready to go, with all the necessary ingredients: a salt water solution (I added a little white vinegar to mine), the knife you want to etch (coating still intact), lots of cotton swabs and a malt beverage. Be sure to stay hydrated!



Up next: the actual etching!

 

[granitestateofmind]

So, now your etcher is assembled (or cobbled together, there's no need to be fancy. First time I did it was with a car battery charger for DC and a 16VAC transformer plugged into a power strip). First, you'll want to use DC to deepen the laser etch; then AC to blacken it so it'll be visible when you're down to bare steel (you are going to strip this when you're done, right?). You'll need to make good contact with the POSITIVE alligator clip. I couldn't get my clip to stay on the bare steel of the edge, and since I will be stripping this knife anyway, I scratched off some of the coating to get good contact with the POSITIVE clip.



You'll need some salt water solution (about 2 tablespoons of salt dissolved in 1 cup of water; maybe add a tablespoon or 2 of white vinegar) to dip your Q-tips in. You don't need much, I've decanted a bit into a recycled yogurt cup here. Make sure your steel is clean; I used a scotch-brite pad followed by some alcohol. Be gentle with the pad (if you need it at all), you don't want to take off any of the coating as this is your "resist"; the etcher only etches steel, not coatings. The sharper the laser etch, the better your detail will be etching:



Next, get your Q-tip clipped into the NEGATIVE alligator clip; the clip has to make contact with the solution on the swab, but you don't want the metal of the clip to touch the metal of the knife. The solution will act as the conductor of electricity, so go ahead and get that cotton wet and flip the switch to DC. Then slowly use the Q-tip to wet the logo area, power on. You'll smell it and see it working, and the swab will start to turn colors as it draws away the ablated steel. When it's black, flip it around and dip the other end and keep going. It doesn't work so fast that you have to be extra careful, but it's a helluva lot faster than soaking your knife in PCB etchant.




After a couple of slow passes. Let it work a little; it's fast, but it ain't that fast. I went through maybe 4 swabs (8 ends) for the main logo, and the etch is reasonable without being deep. Too much time etching will have a tendency to blur a little as the process gets "under" the resist.





Gloves are a really good idea as well as eye protection. You'll need both your hands and your eyes to enjoy your knife when you're done. Also, the alligator clip can get a little warm. Don't forget, you're playing with electricity!

Once I'm done with the DC etch, I was the knife using Bon Ami powder - it's basic enough to neutralize the acid you've created, and cleans things up so you can see how you've done. If it's not to your liking, etch it again. Then clean it and move onto the AC part, which will blacken what you've just done. The process is exactly the same (although polarity doesn't matter, I still use the same convention as the DC process); clip and dip the swab then apply the power. I had to do this a few times; washing in between revealed some spots I hadn't blackened as much as others. The AC process makes a lot more sizzle and bubbles. Not to worry. It should end up looking like this:





So, that's pretty much it. I'm sure I left out a few things, but it really isn't a difficult process. Next I'll be trying to make a few custom stencils for embellishing my 9. I'll post up some more pics of the 12 when it's stripped and fluffed up a bit. Any questions, feel free to ask, and if you want to check out my "ghetto" setup, you can find it here: Electro-etching my new BK 16. I'd say go for it even if all you have is a 9V battery to etch with...it's fun to play with.

 

[dynamicmoves]

Looking forward to seeing the 9.
I might have to try something with a 9V and my trail hawk.

Thanks for posting.

 

[Tdhurl1103]

I saw your other posts concerning this, however, this thread is just way cool. Appreciate the detail and pics.

 

[Galeocerdoshark]

Thanks for the walkthrough, that's really cool granite! Too bad I don't know cr*p about wires and electricity

 

[Zaper]

I like a lot the DPDT switch idea to have an AC/DC or double function etcher/blackener in one unit. It really rocks!

 

[Dexwithers]

Man. So sick. That is the way to do for sure. I'm gonna have to figure out how to make one like this. Just awesome Granite.

 

[zzyzzogeton]

Hey Granite,

Did you make, buy or scavenge the blue converter board? If bought, where? If scavenged, out of what? I have been to a couple of electronics parts stores and none of them have anything like that board already made up. The said they could sell me the parts, but since my soldering skills draw near perfect vacuum,......

 

[granitestateofmind]

Hey Granite,

Did you make, buy or scavenge the blue converter board? If bought, where? If scavenged, out of what? I have been to a couple of electronics parts stores and none of them have anything like that board already made up. The said they could sell me the parts, but since my soldering skills draw near perfect vacuum,......

Standard 12VDC PS board for the alarm industry, comes with the 16VAC transformer (and a 7AH 12V lead acid backup battery!). Email me. I have a few boards kicking around, I'm sure.

 

[mrn8]

Very cool, Granite, thanks for sharing! So, I'm trying to follow your wiring and I have a couple of questions. The transformer feeds into the AC terminals on the PCB board? Also, in the open shot, it looks like your DC is on top and AC is on the bottom of the switch, but the markings on the outside of the box indicate the opposite. Am I missing something there? Thanks!

 

[granitestateofmind]

Very cool, Granite, thanks for sharing! So, I'm trying to follow your wiring and I have a couple of questions. The transformer feeds into the AC terminals on the PCB board? Also, in the open shot, it looks like your DC is on top and AC is on the bottom of the switch, but the markings on the outside of the box indicate the opposite. Am I missing something there? Thanks!

Sorry, I should probably try to draw up a circuit diagram.....the transformer output (16vac) feeds the board and the switch, the 12vdc comes off the board into the other side of the switch. Wires for etching come out of the center terminals of the switch. This type of DPDT switch is of the ON-OFF-ON variety, so in the center position none of the terminals are connected. The toggle in the "up" position connects the "down" (opposite} terminals to the center terminals, that's probably what you're seeing looking at the pictures; if you have a multimeter you can verify this. or you can just wire it up, try it and label after.....one switch position will etch (that'll be DC) one will blacken (that'll be AC). If you are just settin something like this up with a couple of transformers, like an old cell phone charger and a doorbell transformer, for example, you would still set it up the same way: AC into one set of "end" terminals, DC to the other, and alligator clips (or wooden clothespin wrapped with stripped wire, use your imagination) out of the center. Switch one way connects the opposite "end" (i.e. switch "up" connects "down") to center terminals (clips) and switch to "down" connects "up" terminals to center. I'll try to work up a simple drawing that even a non-electricity oriented person should be able to follow, but it probably won't be until tonight. Until then, I hope that clarifies things a little.

 

[mrn8]

Yeah, that clarifies it completely. I forgot entirely that's how those switches work. Now I've got to look around and see if I have a spare 12V power supply that I can dismantle.

 

[NCSlice]

Bump bump

What with a bit of new interest going around for etching, thanks to Jberguns awesome BK16 and BK2 work, I'm bumping this up for those who may be interested.

This is a fantastic setup!
Even though I got satisfactory results using PCB on my 11, this looks to be faster, easier, and just better!
Especially the blackening, which I'm still not satisfied with after several attempts and methods tried.

Thanks Aikiguy for pointing me in this direction and BIG thanks to GSOM for this thread!

ETA: PSA... I highly suggest plugging into a gfci or afci protected receptacle or circuit for maximum safety. You know your receptacle is protected if it has the test and reset button on the face. In most cases there are additional receptacles down line that are protected by the gfci receptacle that is upstream from them. Some circuits are gfci/afci protected by a gfci/afci listed breaker at the panel and the receptacles down line may or(in most cases) may not be labeled as such. A gfci protected power strip is just as effective and acceptable as well.

These can be easily located by pressing the test button on the face of the receptacles or breaker and simply check for power, if there's none, you know you're good. If the test button fails to trip the device or the device fails to reset then it must be replaced because it will also fail to function properly in a fault event causing possible injury or death.

 

[TravisH]

Don't forget those ubiquitous wall adatpers for small electronics.

Outputs in VDC are vastly more common but VAC is not hard to find. Got my 12VAC from a defunct desk printing calculator. Cut the end off, split the wires, strip the ends, attach clips.

 

[granitestateofmind]

Don't forget those ubiquitous wall adatpers for small electronics.

Outputs in VDC are vastly more common but VAC is not hard to find. Got my 12VAC from a defunct desk printing calculator. Cut the end off, split the wires, strip the ends, attach clips.

Of course, make sure it's unplugged first !

Thanks for bumping this up, NC....I'll say that since I built this I use it on every new Becker I get to deepen the laser etch. If anyone wants to see it in action for a pattern etch using adhesive vinyl from the craft store, check this thread here.

 

[Jbergun]

Bump bump

What with a bit of new interest going around for etching, thanks to Jberguns awesome BK16 and BK2 work, I'm bumping this up for those who may be interested.

Thank you for the kind words. I wish i seen this thread before i could have darkened mine up before the stencils got thrashed and trashed. And to add on to the safety and gfci talks. Most hardware stores carry three foot extension cords with a built in gfci with the test and reset function on the male plug end. These are very handy for something like this because most people only have gfci in the kitchen and bath portions of their home.

 

[NCSlice]

Yeah, I was thinking about trying the darkening without the stensil, or enamel in my case. I assume it could be sanded with a flat something or other leaving the black down in the etched area. Or will the AC scar the flat non-design portion?

Those cords are the biz Jb...very handy to have around. I use mine for making toast and mixed drinks while taking a bath lol

 

[Jbergun]

Yeah, I was thinking about trying the darkening without the stensil, or enamel in my case. I assume it could be sanded with a flat something or other leaving the black down in the etched area. Or will the AC scar the flat non-design portion?

Those cords are the biz Jb...very handy to have around. I use mine for making toast and mixed drinks while taking a bath lol

They are indeed handy. I was also wondering that if i tried darkening without the stencil can it sand off of my non etched portions easily. Like NCSlice said with a flat file or something. I know the one spot i touched with the DC etch outside my stencil wasnt terribly difficult to sand off.

 

[granitestateofmind]

They are indeed handy. I was also wondering that if i tried darkening without the stencil can it sand off of my non etched portions easily. Like NCSlice said with a flat file or something. I know the one spot i touched with the DC etch outside my stencil wasnt terribly difficult to sand off.

The blackening from the AC is pretty easy to get off....unfortunately. For etches like lettering or fine lines, it'll stay pretty black.... but if you have large areas of "pits" between the "lands" (pits are where it's etched, lands are the raised, unetched part) the black will come off where you've etched pretty easily. I scrubbed it out of the pattern I put on my 9, as that knife seems prone to rust and so gets the ScotchBrite treatment pretty regularly. Oh, well. Still looks OK, but I'd have to use a sanding block every time I wanted to clean the knife - and I'm a low (to NO) maintenance guy. So, off it came.

Before:

and after:

Still visible, but it's a user.....

 

[Jbergun]

Your 9 is what inspired me i think it looks great before and after i read before you said its not perfect but it is yours. No one else has a bk9 like that. Thanks for the info.