Chris Crawford Electro-Etch Output

TXscout

TXscout

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Jul 9, 2008
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I just built an electro-etch box, following the instructions on Chris Crawford's site:
http://chriscrawfordknives.com/#/electro-etching-unit/4535265119

I just checked the output on both AC and DC channels with a multimeter and got 25.08V on the DC channel and 28.40V on the AC channel. Is that pretty much within specs for this unit? I just want to double check, especially the AC output. Anyone that has built one--Your feedback is much appreciated

Thanks in advance
 
Interesting, I just finished mine about 5 minutes ago. I'll check and get back to you.

Question: on the third page, when it comes to wiring, did you wire the mid-level transformer output to ground? I'm not sure that particular instruction was correct.
 
Yes, the black wire (in between the two yellows) I connected to ground--I followed his instructions exactly. I believe if you use one black and one yellow, instead of the two yellows, you'll get 12V output versus 24V (if I understand correctly).
 
sounds right, don't fret over a few volts

If you search on chris crawford etcher & burned stencils you will find more info

Many others reccomend to go for a 12 volt output.

If you bought that exact transformer, just use the center tap wires to get 12 volts.
 
I wired up a switch to go between 12 and 24 volts.

At the 24 volt setting, I get 29 measured AC volts, and 25 DC.

At the 12 volt setting, I get 14.5 vac, and 12.4 vdc.

The reason I was curious about the middle wire to ground was because (1) there was somebody (Erin a.k.a. "Hypocrite") who had some trouble blowing fuses, and (2) I used it in the switch rather than grounding it.

This is kind of cool - next I need to get a stencil!

Tait

P.S. This was my first significant electrical project that actually worked on the first attempt.
 
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Some disagreement on importance of grounding that extra wire appears in this thread, starting around post 60.
 
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I never thought about adding a switch, with the black, middle wire to give you a 12 or 24V option...might rig one, tomorrow. This is pretty cool--Ive got to get some stencils, too.
 
I just tried etching some scrap using strips of electrical tape as a resist - it's super cool - now I need some stencils!

For the switch, I used the Radio Shack SPDT (here) - came to less than $3 with tax.

Best wishes!
 
Wow, you guys must of had a hell of a time looking for all the supplies. How much did it end up costing you guys? And did you use all the materials it listed for?
 
Radio shack had everything in stock that I didn't already have, and yes, the listed materials were all used. I did have to make a second trip when I figured out the 12/24V wire issue. Out of pocket less than $60.

It came together pretty quickly for me.

And it's fun to build stuff :D
 
I ordered everything from Radio Shack, and they had it here the next day-- $66.23 for everything on the list, shipping and all.

I had all of the non-RS stuff on the list, and used a hot glue gun, instead of the foam tape, to mount the transformer and the bridge rectifier to the box.
 
Awesome, You guys should post some pics of your rigs! and that etching you just did.

I haven't done much etching. but when I did it I did it fairly simply. I followed This thread from britishblades.com its so simple, but wow was it powerful, I etched halfway through the steel in 20 mins. All I used was a 9volt, saltwater and some vinegar. its pretty cheesy lol. but looks fine.
 
Yeah, I'm with ThirdEye on this one, a battery does a nice job alone. I have a small 12v battery and just attached some alligator clip leads to it and got great results. The stencil seems to be the most demanding part. I had mine cut out of vinyl. Stick it to the blade and no leaking underneath. With a 9v battery, you can actually use two to get 15-18vdc and you work better than 12v or 24v. I never understood why the electro-etch boxes are either 12v(underpowered) or 24v(burning stencils). 18V would seem to be the perfect in-between.

Don't get me wrong, I'm all for building tools. My Titanium anodizer is great. Except after $75 in parts, I learned I could do the same thing with $7 worth of batteries.
 

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Thanks for the input - I built the etcher in part because I wanted to have the darkening ability of AC - has that been an issue for you?

I haven't tried with stencils yet; but the steel does get pretty warm with just electrical tape at 24 V. If I had to guess now, I would consider 24 V for the DC portion and 12V for the AC portion of the etch.

I think I'll try with stencils and see how I do. If it seems like 18 V would be better, I'll try and figure out if it's easy to modify the circuit to provide 18V.
 
I used Vinyl stickers and just printed on them and cut out the stencil with an xacto blade. It works well, there's no bleeding under. You can purchase large packs of them online or at a local office supply store. There labels, but make sure there vinyl, or something with a gloss. But I also used nail polish like in the thread and there was no bleeding as well. If you are asking us about having issues with darkening with our method, I'd say yes. But all the pics on that thread showed blackening. It was black at first, and during the etching process, Had to change the cotton even cuz it got so charred. But it just wiped off my etching it didn't blacken. So heck yeah, those are much better. I didn't like how it was just a depression, like a stamp. I want an etch! Sorry if you were talking to the rest of the people who made the Electro-Etch.
 
JFYI, the difference between the AC and DC output is due to the voltage drop caused by the bridge rectifier ( I haven't seen Chris's plans, but am sure that is how his works).
The AC output should be about 3 volts higher than the DC output.
 
tait said:
I just tried etching some scrap using strips of electrical tape as a resist - it's super cool - now I need some stencils!

For the switch, I used the Radio Shack SPDT (here) - came to less than $3 with tax.

Best wishes!
Click to expand...

How did you wire the three tabs of the SPDT switch? inputs on outer tabs and output from center tab? Also, which AC input/pin on the bridge rectifier do you hook it up on? I need some coffee!
 
I think there's more than one way to do it.

In the schematic, there's a wire from transformer wire 2 that goes to pin 1 on the rectifier and pin 3 on the dpdt switch. On the Chris Crawford website, transformer wire 1 is used instead.

What I did was made transformer wire 1 go to one side of the switch, transformer wire 2 go to the other, and the middle wire of the switch goes to the combination of pin 1 on the rectifier and pin 3 on the dpdt switch.

The goal is to switch the wire contacting pin 1 on the rectifier and pin 3 on the dpdt switch between wires 1 and 2 on the transformer.

It helps to use a continuity tester of some sort and play with the switch - for example, the "up" position on the switch connects the two BOTTOM pins, and the "down" position connects the two TOP pins.

I hope that makes sense.
 
I figured it out, thanks a bunch--Works perfectly. I ended up moving the controls around so they made sense to me, and the fuse to the back.

24loevm.jpg
 
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