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Electro Engraving Problems

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vtsteam:
Ade it's a disease!  I've totally stopped productive work on my ELS and lathe to concentrate on this stupid etching thing to make a metal version of simple label I can print and attach in a few seconds, if I were satisfied with paper. This is just bling. But ya know, I just hate it when I find I can't do something, that I know otherwise CAN be done, no matter how trivial the ultimate purpose is.
 :doh:

ps, and now I've gone on Ebay and ordered a sheet of the the film type PCB photoresist, some overhead projector film (laser printer compatible), 5 sheets of Press-N-Peel transfer paper, and a new black laser printer toner cartridge (but again not OEM -- they are $100). Fingers crossed that at least one of these things will make a reasonable difference.

ps, Ade I think lye is a first rate paint remover, so even though it does a good etching job on aluminum, I'm guessing it's hell on resist -- as happened in your trial. Even though aluminum is much more resistant to acids than a base, the electolysis method may speed the acid's effect up. That's just a theory -- possibly contradicted by reality. But the reason why I'm trying vinegar/salt and volts.

sorveltaja:
Does the plate have to be of aluminum? If sodium hydroxide was used, it has some kind of thermal(or something like that) reaction with alu, that causes uneven etching and pitting. 

In general, aluminum is a bugger to etch any delicate figures, be it chemically or electrochemically. But that's just my experience; there could well be ways to get better results.

     

AdeV:

--- Quote from: sorveltaja on January 22, 2021, 11:36:45 PM ---Does the plate have to be of aluminum?
--- End quote ---

I think we were trying aluminium because it's cheaper than brass! I'm fairly sure the final plate will be brass. I only have bits of aluminium (or steel) sheet lying around; or copper-clad circuit board - but I know I can etch that stuff using laser toner as resist, but that doesn't make for a nice plate to go on a machine...


--- Quote from: vtsteam on January 22, 2021, 01:18:12 PM ---ps, Ade I think lye is a first rate paint remover, so even though it does a good etching job on aluminum, I'm guessing it's hell on resist -- as happened in your trial. Even though aluminum is much more resistant to acids than a base, the electolysis method may speed the acid's effect up. That's just a theory -- possibly contradicted by reality. But the reason why I'm trying vinegar/salt and volts.

--- End quote ---

I think the resist was OK - the letters just floated off & were sitting on top of the lye (on the bubbles) - complete, but detached... However, my sum total prep on the aluminium was to give it a scrub with some dry scotchbrite, I didn't try to degrease it or surface prep it any better than that; so it's possible the toner wasn't stuck down as hard as it should have been. Also, I did have a fair bit of trouble getting the plate through the laminator, it's a bit thicker than PCB (2mm vs. 1.6mm) and I suspect that was a bit too much for the poor thing. It only cost me £10 (about $13), so it's no big loss if I do kill it.

I took some photos of the process, including the epic fail, I'll put them on a different thread though, I've polluted this one enough with my nonsense!  :palm:

Pete.:
Ade I have a huge sheet of reclaimed brass if you need some. I think it's 18 or 16 gauge. IT's got cotact adhesive one side and (unbelievably) brown paint the other but it comes up well with some careful scraping of the glue and rubbing with scotchbrite.

vtsteam:
For me the final hoped for plate is brass, and I have a small piece large enough for only two tries. So that's why I'm starting out with aluminum. I have yet to get a qood resist copy except by the CNC/laser paint removal method -- and that one wasn't ideal. So until I get the resist part of the equation done, there's no point in going to brass yet.

As for the etching of aluminum with good detail, if you watch the first video I linked above, you will see a very clean edged aluminum etch with the vinegar and salt electrolysis method.

As for sodium hydroxide and resist, in the second video I linked above, sodium hydroxide is used to remove the film based photoresist after the etch is over. It does actually float up the resist, it doesn't dissolve it.

When I was 7 my mother got a 55 gallon barrel, set it up on bricks and put a load of wooden house shutters in it. Then she put water and lye in ( I was very impressed with the label's skull and crossbones) and lit a wood fire under it. This removed all of the century-old enamel paint layers from the shutters in a very short time. This was in the fifties before modern paint strippers were common where we lived.

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