etching enclosures.... shallow, eating toner...

[jplebre]

Arghh... no, let's keep calm

So, I'm following what some guys here do:
Sand box (starting with 1200 grit paper and going down to 200)
Clean box (lighter fluid)

transfer the pnp. Unlike with the PCB's, the toner only transfers half of the ink on the pnp. What's going on? any tips on this? Almost thought that the heat could be sucked off the junction area due to the size of the box? (like when you solder a cable still connected ups lol).

I covered with a etch resistant pen (i heard it doesn't work to well but can help right?) everything else covered with nail varnish (pink! Why oh why did I ask the missus to buy me the varnish???)
here's a pick:


So, i put it on the bath with the etchant. on a 40% solution I diluted it 3 thirds of FeCL 1 of water.
I was moving the box in the etchant constantly (constant agitation) and had put the little toothpick sticks to raise the box when resting.

nothing much was happening for the first 2 minutes. After 2 minutes first time I raised the box there was minur bubbling ONLY on the bit exposed! All good I thought. 2 minutes later there was nothing.
I tried to warm the etchant a bit and I had some more bubbling. This is the result:


Any ideas how to avoid the 2 etching "steps"? maybe heating it was what went wrong?
What about the "half transfered toner"?

[glops]

Are you printing with a laser printer?  Sounds like you didn't iron it for long enough.  I use store bought ferric and don't dilute it.

[jplebre]

Yes, an old monochrome HP from my office, using RapidOnline stack PnP blue.

I've Ironed it for 10 minute applying pressure. Then the shopping arrived, I turned the heating to max and grabbed the shopping. 10min later came back and applied pressure for another 5min.
I do less than this for my PCB's :S I apply about 10min at "3" on the iron and it transfers the whole thing.

I diluted it because it happened to me what happened to Frequency Central on his other post with the same Rapid FeCl. Heat, bubbles, the whole shebang!

[.Mike]

Man, I typed a lengthy response to this earlier this afternoon, and I thought I submitted it. I spent all day installing a new floor in my kitchen and came back to find that I forgot to hit submit... heh!

Anyway, from my experience, the difference between transferring to a PCB and transferring to an enclosure is that the PCB conforms to the shape of your iron under pressure, and the enclosure does not. This is an even greater problem because it seems that most enclosures are high around the edges and low in the middle. A flat iron will never hit the middle of the bowl, which happens to be right where we all want to etch. Good prep overcomes this.

I think, when preparing an enclosure for etching, it should be looked at as two different processes: flattening, and smoothing.

To flatten, you need a sanding block, and some 80 or 100 grit paper. Take a marker, like a sharpie, and color the entire top of the enclosure. Sand while applying even pressure to the sanding block, making sure to keep it as flat as possible. I like to make sure the block is over two edges of the enclosure as much as possible, to increase the chance that the box ends up flat. As you sand, the marker will slowly be removed, first in the high spots, and eventually to the low spots. It will probably take a while.

Once you have the box flat, you can move on to smoothing, which is much faster and easier. All you have to do is work up in grit as high as you want to go. Since the box is as close to flat as you can get it, it takes just a few minutes for each subsequent grit.

I have used a random orbital sander to save time and effort on the flattening of some blemished powdercoated enclosures that I have bought, and then finished the flattening with the block. It works well.

Transferring onto a flat box is a night and day difference. I use dollar store photo paper with a sheet of plain white paper on top. I use 75% power for one minute, no pressure. Then I turn it up to 100% power, 1 minute, no pressure. Then, I do about 3 minutes of moderate pressure (the weight of my arm), then 3 minutes of moderate pressure while moving the iron, and then one or two minutes very carefully with the sheet of paper removed until I see the design come through the paper. 10 minutes total. My only screw-ups are from too much pressure, too much moving, or an alignment error.

Now, for the actual etching, I didn't have good results with the method in Slade's tutorial. Not being able to see the reaction made it difficult to tell how far along it was. I prefer to cover the whole enclosure in tape, and etch it face up. I use a toothbrush to grab a bit of acid/peroxide mix from the container, and lightly brush it on the metal. This allows me to see the reaction and gauge if it is too fast. If it's too fast, or too hot, or etching into my mask, I can dunk it in water and start again with more caution. I can also see when the etchant is spent, which happens rather quickly. I dump it into a waste container for proper disposal. Another benefit, I think, is that the face-up bubbling action seems to help keep the solution oxygenated. I can etch a 1590BB, about 50% coverage, with about 4 tablespoons of acid/peroxide mix (50-50). This method does take a while, particularly if you sanded to 800 grit or higher. It seems it takes a while for the acid to begin eating very smooth metal.

And last, I am not a fan of nail polish. I use Testors enamel. Nail polish melts at a lower temperature, and I have had it melt and cause pitting.

Good luck!

Mike

[davent]

For flattening the enclosure you might find it easier to attach a sheet of sandpaper to a large flat stationary surface and then take the enclosure to the sandpaper rather then sandpaper to enclosure. With a sanding block i find it difficult to not rock the block a bit and round things off some. If i'm holding/moving the object i'm sanding, against a stationary surface i can apply more pressure and maintain the desired alignment much more easily... just a thought.

Take care!
dave

[deadastronaut]

heres what i do always..and have great results..
1: block with coarse grade paper..water/washing up liquid. sand until uniform, till those casting veins disappear, hence the coarse brutal paper...
2: clean..thoroughly..
3: print at best quality, turn toner saver function off..
4: iron for a few minutes...i tape my image to the box and table so it can't move/smudge etc, it really doesn't take long to heat up the box/toner..
5: while hot put into a sink, run cold water on it...remove paper...let soak...rub paper off...use toothbrush to get rid of tiny remnants..(obviously not in your case of pnp)
6: nail varnish large areas..
7: warm water, mix ferric...
8: put in etchant, agitate every few mins..i leave mine in for around 30-40 mins..depending on ferric mix..(until you see an edge appearing)
9: rinse, use toothbrush to get all burnt ally out of gaps n crevices..
10: use coarse grade again..then finer stuff..400-600...until you are happy with it...go finer if you really want to shine it up..
11: drill
12: dab paint into etch...let dry, sand again to get off excess...and any scratches on sides from drilling etc...
job done... i clear coat mine just to keep the shine shiney...optional..

[jplebre]

Hey guys

the rounding off makes sense!
@.Mike thank you for your lengthy reply I'll definitely try those tips for my next enclosure (have 2 more to do for now).

I also followed (to an extent) Mark's tutorial on the galery.
Oh well next saturday I'll melt more enclosures

[jplebre]

Ohh we posted at the same time!

Cheerios Rob tips noted.

I also noticed some people's transfer is smaller (ie only toner around the finer details) might do that and cut out larger areas for bubbles etc.

[boogietone]

You should be sanding first with the 200 (coarse) and then with the 1200 (fine) paper.

[jplebre]

Alright

The block tip did help with the sanding.
It figures what I was doing "wrong" was not let the enclosure cool down enough before removing the PNP.  It takes twice as long as the PCBS'.... Doh!

Now the toner is there.

I'll try to paint as soon as the paint arrives.

@Rob what do you use to apply that cool shiny finish? I'm more interested in the protective effect of it than the shiny bit.

[deadastronaut]

^ i stick a coat or 2 of car clearcoat./ clear laquer....sometimes i let it air dry, sometimes i stick it in a toaster oven,it bakes the laquer fast, and stops crap/dust falling into the wet laquer also...

in fact i have 2 boxes that i sanded a few weeks back that still need drilling etc...and i really see the difference in 'dullness' compared to the ones ive clearcoated...shiny shiny...

[jplebre]

Nice! I think I need to stock on car stuff now

[jplebre]

Unfortunately, it'll have to come on the next delivery
the paint has dispatched already