Etching power supply question

S

StuNY

Joined
Feb 16, 2014
Messages
152
I have just received my stencils from Ernie (First talked on Friday, in my hands Wednesday- nice!) as a step up from my iron on laser prints. They are very nice and I can see why this is much better than taking shortcuts with other methods. So I used them first with a bottle of fluid (http://www.knifemaking.com/SearchResults.asp?Search=ECE01) from Jantz I also just received instead of the homemade vinegar and salt solution I was using before. Says it is for stainless through tool steels so thought this would be good. So, worked perfectly with my 15 volt DC power supply and cut a nice etch. Then switched to my 12 volt AC power supply to get the darker color deep in the etch. Didn't really do anything on my CPM 154 test piece. Tried just the AC etch on a blank piece and just a faint ghost but nothing black. Switched to a piece of O1 steel and got a nice dark imprint.

So, the AC power supply I had around was probably not ideal- it is 12v AC at 40 kHz, not the 60hz that most seem to be using. Before I pop into Radio Shack tomorrow and grab a 12/24v AC transformer I thought it might be a good idea to check with the experts here and find out if Stainless is just harder to get the black etch on, if I am using the right etchant, or if I should just get the 60hz transformer and all will be well?

Appreciate any help.
Stuart
 
StuNY,

Your 12 volt supply at 40 KHz has got to be the problem. At this frequency, there's probably not enough time for material to be transferred between your anode and cathode before the polarity is switched. The back-and-forth transfer of material is what creates the darkened etch. 40 KHz means that the plus and minus polarity is changing every 1/40,000 (.000025) seconds.

A 60 Hz power supply will change polarity every 1/60 (.0167) seconds.

Go get the cheap Radio Shack transformer and wire it for 12 volt ac and I bet that you will see much better results.
 
I've had this problem as well, and I was using a 12v 50w transformer @ 60hz. Had little to no effect on S90V, and inconsistent results on 3V.

My guess as to why I had problems it the S90V is that it was still contaminated with the original electrolyte from the DC stage, and in the case of the 3V I suspect the wrong electrolyte. I'd love to know if someone has a better theory. I used the two electrolytes TUS sells for DC and then AC etching on stainless.

On the plus side, I've compared a darkened etch to one that isn't, and prefer the subtle effect of DC only when it comes to my marks. I do prefer a darkened etch on sanded or stonewashed finish if it is something that I want the eye drawn to, such as a special etches for a customer. For really technical, or one time etches with very demanding geometry I'd rather pay a laser engraver to ensure a perfect result. The downside to that is I like deep etches, and lasers just don't burn deep enough to make me feel like it will last forever.
 
I would like to suggest that you consider a better etchant for your stainless steel blades. I am now using # 97 from IMG in New York and it has made a difference in the quality of my etches on stainless. Call them and get a quart...you won't use anything else after.
 
First, if it is plugged into the wall socket, it is delivering 60 Hz. Transformers operate at the frequency of the incoming line. 40Khz is a radio frequency.
Second, it is the current that you have a problem with. I bet you are using a small charger type transformer rated in milliwatts. Use a 1 amp 24V center tapped transformer and you will be able to get 12V and 24V at sufficient current to etch and mark.
 
Thanks guys, pretty sure problem is the power supply frequency. This is a solid state unit used to power halogen lights (yes I know they are normally dc) but it is pretty clearly marked at 12v AC at 40 kHz output and about 3 amps so don't think it is just a current issue. Just wanted to make sure everyone else was getting black on stainless before picking up a transformer at the proper frequency. Radio Shack around the corner so will pick one up at lunch.
Stuart
 
OK, that is a power supply, not a transformer. 40KHz would be really fast reversal of current rate, and I really don't know how it would affect etching/marking. probably not well if your results are an indication :)
 
zaph1 said:
I've experimented with those units. Pretty worthless for etchers, but very nice for lighting. Try this unit, I've used over 100 of them and they are very solid.
Click to expand...
Thanks, that is pretty much what I just picked up at RadioShack (I think it had been hanging from the same peg for 10 years from the looks of it!). Think I should tap for 12v or 24v? Will do some tests, but thinking of starting with 24, but want to avoid burning my stencils.
 
Go to your local hardware store, ask for door bell transformers. They usually have 8, 12, and 16Volt taps. They are also designed to work with low impdiance loads. I've been using the same one for the pasr 35 years.
Get the one with three terminals, costs about $15.
Jim Arbuckle ABS JS
 
I'll post a schematic tonight. It is pretty simple to build a quality etcher comparable to the personalizer plus in ability. Skimping on components is not cost effective, as you will end up with a second rate etcher. All the parts should cost less than $50. EBay is probably the simplest place to get them, but a full Radio Shack will have them, too. If you have a parts box from your old electronics hobby days, most of what you need is probably in there.

The parts list are:
Transformer - 3 amp 120VAC input/24VAC center tapped output. - http://www.ebay.com/itm/Transformer...uit_Breakers_Transformers&hash=item4ac52e51bd
Indicator lamp - power on indicator, 120VAC red
Power cord from old lamp, etc.
SPST switch - main power switch ( On/Off) 120VAC 5 amp
SPDT switch - 12V/24V (Hi-Low) switch 120VAC 5 amp
DPDT switch - Etch/Mark switch ( AC/DC) 120VAC 5 amp
Bridge rectifier - AC to DC converter , 120VAC 5 amp
Red and black leads with alligator clips
Etching block and pad - USA Knifemakers or other
Etchant - USA Knifemakers or other
Box for etcher...a small plastic tool box works well and the tray can store the supplies.
 
Well... note to self... just do it the way everyone else (and the schematic!) is doing it and don't cut corners! The radio shack ac transformer worked perfectly, nice black letters from the AC into the deep engraving from the DC. Didn't damage the stencil at 24volts and worked it's magic quickly. Thanks again everyone- time to get logos on my latest batch of CPM-154 knives!
 
Here's a schematic that I made years ago. Many people have used it to make their own etchers. It's based on Chris Crawford's design but is shown as a schematic which many people find easier to understand than the written wiring instructions on the Crawford website. http://www.logiudicecustomknives.com/knifeshop/etcher/electro-etcher_circuit.pdf

A parts list is here. http://www.logiudicecustomknives.com/knifeshop/etcher/index.shtml Again, based mostly on the Crawford list. I used a different (more expensive box than the Crawford design, etc), but the items can probably be bought for about $60 if budget shopping.

There's other plans available out there too.

Good luck,
 
Thanks Michael, I found your schematic earlier and that is what I used to buy the parts today! Appreciate your taking the time to post that and respond. I had most of the other parts already so once I got the proper AC transformer all went well!
 
Logem
Schematic looks good except the red output jack is hooked to the negative out from the bridge rectifier and the black to the positive. Conventiom is just the opposite. However the polarity on the electrodes is correct.
Jim A.
 
A bunch more etching and testing... 12v works fine for DC and AC so no real reason to have voltage adjustment as far as I can tell. Really getting perfect etches now, what a difference from my qtip and iron on laser print days! Great stencils from Ernie as well, after about 20 etches still looks as good as new. One thing I saw somewhere online that I incorporated is for the applicator head. I cut a piece of graphite down to just a bit bigger than my logo, attached it to a piece of HDPE with a bolt/wire by threading the graphite. Put a cotton pad over it and it doesn't corrode at all with the etching. No maintenance required : )
 
You must log in or register to reply here.
Back
Top