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Discussion Starter · #1 ·
I used to etch and engrave brass (same method as used for printed circuit boards) using the toner transfer method. Now that I can cut vinyl, for most designs I can just use cheap vinyl instead of dealing with the transfer. Also, I was never able to get the toner transfer method down pat without making it horribly expensive. With the proper laser printer, toner transfer sheets, and hacked overpowered fire-hazard laminator, I'm at the point where I should just get emulsion/sensitized rolls and a real laminator and then UV expose the brass.

I really only have one design (in two parts) that's too detailed for vinyl, down to 0.5-1mm ovals. I had taken it into a few screen printers in my area about eight years ago, but all of them wanted a minimum order of at least 100 (plus none of them could guarantee it would even work), where at the time I was only doing 20 a year at the most, so paying the setup fees, the minimum order fee, plus having to buy 200 sheets of brass killed that idea so I kept going with the toner transfers. I may start doing more engraving now, and I'm curious as to whether or not I could pay someone here to make a screen for me (along with use and care instructions) that I can use on my own when I need to make one.

The design is 3.5" x 9.75" that would be put onto 4" x 10" 0.010 K&S hobby brass. I wouldn't need any kind of precise registration, as long as the whole image is on the brass the alignment doesn't matter. I would prepare the brass by lightly scouring with 2000g wet/dry sandpaper, then cleaning with acetone, then distilled water. After printing, it would be etched in an acidic cupric chloride etch bath, then cleaned with acetone again to remove the inks.

Are there any inks out there that would be able to print on brass without beading up? Would they be usable at home without having to need a fume hood or UV cure booth? If I had the screen in a frame without a full press, could I just put the brass on a thin piece of wood thick enough to create the tension, and then clamp the screen over it to squeegee the ink on?
 

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You could use solvent ink although I am not firmiluar with the actual etch bath your using. Is it the common etchant that you use on PCB. If so the solvent ink should hold up. Years ago I did PCB's and I used a sensitizer on the copper boards then use a film positive and exposed. The a developing solution and in the etchant they went. Was a fairly inexpensive. I did buy a bunch of 380 screens from a guy that was doing something similar to you. I can make a screen if needed.
 
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Discussion Starter · #4 ·
Thanks. I've actually been surprised at what holds up in the etchant bath (scotch tape!). It would be nice if it sticks well, as a recommendation to speed up the process is to gently pass a brush (toothbrush or nail brush) back and forth over the etching surface. The standard etchant is ferric chloride. Cupric chloride is actually regenerative, and my batch is leftover from a few years of ferric chloride etching. You recharge with strong peroxide or air bubbling, and keep the pH low (acidic) with pool acid. I need so little that I basically never need to dispose of it.

I'll probably ask in the Wanted section whenever I'm ready to start doing this again (not for a month at least). My main question would be can I easily squeegee it on at home. To me, screening it feels easier than having to worry about exposure times, etc, on sensitized laminated emulsion.
 

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Yes you can easily squeegee it on solvent ink is fairly thin that's why the high mesh combined with the small detail you need.

Palm beach.. I lived in Stewart county in '87 for about a year. Lived on other coast for 14 years.
 

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Right. It is very thin, has body almost like a non-opaque water based, but has a lot of "tack" to it (at least in my experience) so a high mesh + sharp as heck squeegee. I learned that printing on hard (non-fabric) substrates is not forgiving. that is, you're not going to push a little extra ink "through" the brass like could happen on a shirt, either you get it right or totally smudge the crap out of it.

I'm sure most of you all know this already, but had to learn the hard way myself.

Also, something I didn't mention was the curing. The Nazdar I've been using is air-dry but it takes quite some time. It will be tacky for a while so keep it away from dust and any other contaminants (my first instinct was to kick on a fan, a dusty fan.) but there are instructions on how to heat set it. I tried to blast it with a heat gun but that just made it bubble so I stuck with the air dry method.
 

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Discussion Starter · #7 ·
At least with brass I can just clean it off and do it over again. My other issue would be screen maintenance. I would probably try to do at least 10 at a time once I get the process down. I'm used to (trying to keep)ing my projects dust free since I do epoxy embedding with some of it. Easier said than done. I could probably make a stack of thin boards with little rubber feet just high enough to keep it off the brass and keep stacking, then put the whole thing in a plastic box and stick it in the sun (or the back of the car) for a few days.

One of these days I'll learn some basic screen printing but I already have too much money invested in sign vinyl and transfer equipment that's still not actually making me money yet.
 

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I still haven't tried it, but one of our reps has mentioned she knows people who use plastisol for etching PC boards. Prep it (sounds like you're doing that quite well) print it, and flash gel/cure it (you could use a heat gun easily for this method) and then you can just rub it off after it's etched.

I'm sure enamel would work, or vinyl, epoxy, etc. but you'd have to use abrasives, or some nasty stuff to take it back off.

Let us know what you end up trying, and how it works out--I've been thinking I need to do a few vanilla audio pre-amp boards sooner or later... I'm just not looking forward to drilling all those little holes. :)
 

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Discussion Starter · #9 ·
I'm used to using acetone to remove the toner. Acetone really isn't all that toxic (despite the fumes!) compared to a lot of solvents out there, otherwise nail salon workers would be dead in a few weeks. I wouldn't want something that I'd need to use lacquer thinner with, since that stuff is much nastier.

I've never actually done PCBs. If you have a vinyl cutter capable of doing the design you make, I would definitely do that, it would be much easier than any other method and I'm sure vinyl would hold long enough to etch with. If it's a simple design and your cutter doesn't like thin traces I would just make them wide enough to cut. Ten years ago you couldn't get a $300 craft cutter, people came up with all sorts of weird ideas to make PCB etching easier, including a similar process like the DTG machines here, taking apart an Epson and making it a flatbed printer. I don't think anyone really had much luck finding an ink that would stick though. It's less and less common to find ferric chloride in Radio Shack these days but you can find it online in dry form that can be shipped.
 

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Just throwing the option out there--I know you can print plastisol on nearly anything without it beading up, and assuming it's not contaminated, you can use a heat gun (or blow dryer, even) to gel it for etching.

And you have a point, acetone is not unusually toxic as far as solvents go, but a process using no solvents is even less toxic.

The vinyl definitely works, but I did some time in a few sign shops, what I do for PCB work would not be something I'd be interested in weeding--say, a hundred traces, on a board that's 3x3 square times five or ten--not my idea of a good time. (that's almost as bad as having to drill it :) )
 

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I made PCB out my house for 3-4 years and use a drill press to drill them all. After a few weeks I ended putting registration marks in the corners so after etching I would drill registration marks stack them up put steel dowels in the corners taped all together and drilled 10 at a time. I went from 6 to 60 an hour.

I may try the plastisol this weekend. I have a few PCB blanks laying around and I am sure the local electronics store has etchant.
 
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