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californiamilleghia
californiamilleghia Reader
7/19/18 9:45 p.m.

When you use the salt does it leave any nasties in the water when you are finished ?

Hate to have the HazMat guys around asking questions !

Wally
Wally MegaDork
7/19/18 9:51 p.m.

In reply to californiamilleghia :

I hope not, I dumped mine down the sink when it was over.

Keith Tanner
Keith Tanner MegaDork
7/20/18 8:36 a.m.

There was a note earlier from Nohome about being careful with stainless steel because you can generate hexavalent chromium, so it might be worth investigating alloys.

It's been a long time since high school chemistry, what can you make with water, salt and aluminum? Or brass?

ProDarwin
ProDarwin PowerDork
7/20/18 10:53 p.m.

So I tried with a good battery.  It seemed like nothing was happening for a solid two hours.  I mean stuff was happening, but very very slowly. 

I decided to leave it for a while, came back to find this:

 

 

Not sure what happened, but somehow it accelerated dramatically.  My test part looks like this now: (those etched areas are very deep)

ProDarwin
ProDarwin PowerDork
7/21/18 5:43 p.m.

So I believe what happened is there must have been a light coating on the cathode last night.  As that wore away, the etching accelerated.  Today I made a few changes, but I used that same piece, and the instant I put it in the tank and connected the wires, lots of bubbling/activity began to take place.

Attempt #2:

  • Using a proper battery this time
  • Oriented the 'etching surface' perpendicular to the cathode (in an attempt to make the surface as equidistant as possible), which means standing it upright

Annnd.... cathode failure (there was a hole through the part and a wire wrapped around it)

 

Now I'm wondering if I do a proper connection.  Drill and tap the part, attach wire with a ring terminal, then seal it with silicone, preventing it from basically etching itself away.

ProDarwin
ProDarwin PowerDork
7/21/18 6:55 p.m.

Attempt 2.1:

EastCoastMojo
EastCoastMojo Mod Squad
7/21/18 7:10 p.m.

In reply to ProDarwin :

That looks really cool. yes

Keith Tanner
Keith Tanner MegaDork
7/21/18 8:37 p.m.

No kidding. I want to know more about the design.

Remember that aluminum forms a layer of oxide, that should be cleaned off first. Perhaps that’s what you burned through. Scotchbriting the piece before it goes in the tank will help  

For an electrical connection, I’ve been able to successfully fan the wire out and just tape it to the clean surface. If you get a water leak, it’ll corrode. I’ve never run anything as deep as you have. 

ProDarwin
ProDarwin PowerDork
7/21/18 9:37 p.m.
Keith Tanner said:

No kidding. I want to know more about the design.

Its smith mountain lake.  I've been going there since I was a kid.  My parents retired there ~5 years ago.  I making a piece of 'art' for my mom.

I was able to use Google Map Customizer to tinker with the CSS and basically show only water and land with in 2 flat colors.  Then I did a little cleanup in photo software - removed the smaller waterways and some of the small islands.  I set the resolution to something crazy like 5k x 5x and then used a scrolling-screencap plugin to take the screenshot (it takes a ton and splices them all) so I didn't lose the small details.  I probably went overkill, but originally I was thinking of doing a piece up to 24" square, so a typical browser screenshot wouldn't cut it.

I have some text to add as well as a compass on the final piece.

 

Keith Tanner
Keith Tanner MegaDork
7/21/18 10:34 p.m.

That’s not “art”, it’s art. Can’t wait to see the end result. 

ProDarwin
ProDarwin PowerDork
7/29/18 9:47 a.m.

Cutting the final vinyl now, will try the etching with steel this afternoon.

 

Keith, could you provide a little more detail on the iron-on method you used on page 1 that allows for the use of a gradient?  What specific paper did you use?  Is that achievable in a standard inkjet printer?

ProDarwin
ProDarwin PowerDork
7/31/18 1:34 p.m.

For the steel cathode I drilled through and used a nut+bolt to clamp the wire.  Then I caulked around it to minimize any leak.

 

 

(The caulked part will be submerged in the future)

 

 

I ran a test but the anode had too much scale on it.  The actual part I wanted to etch doesn't have scale so I'm not too worried about it.  This goes in the tank tonight:  

The dots at the corners are to prevent it from etching where the standoffs will be attached to mount it when complete.

 

stylngle2003
stylngle2003 Reader
8/1/18 3:29 p.m.

That's very cool.  Smith Mountain Lake is gorgeous.  There's a wonderful wooden boat show there every year.

ProDarwin
ProDarwin PowerDork
8/6/18 7:29 a.m.

Small update:  

Etching is done.  I made the mistake of removing the mask early though.  

Unlike aluminum, when steel is etched it doesn't provide a good contrast between the etched and un-etched surfaces :(  If I left the mask on I could allow the etched areas to rust a bunch.  But I didn't.  Now my hope is to let all of it rust and then sand/polish down the raised areas, which will be quite difficult.

 

(This pic shows the best case contrast.  If you look straight on its much harder to see)

ProDarwin
ProDarwin PowerDork
9/3/18 7:27 p.m.

So another update.  I took the above piece and decided to let it rust a bit, then block sand down the top layer to get the contrast back.  This did not work for 2 reasons:

1) the etching depth was not consistent.  Near the center of the plate it was too easy to accidentally sand the etched areas instead of just the lake design.

2) The rust pitted the un-etched areas too much so I couldn't really sand it down enough to get the smooth metallic finish back.  Oops.

 

Time for attempt # ??

This time I used the plate above as the anode for a new plate I was going to etch.  To make sure the etching was consent, I held them offset from one another a fixed amount:

 

 

This worked really well except it draws ALL OF THE AMPS!.  I really need to hook up a real 12v power supply so I can regulate the amperage.  The etching only took a few minutes... the same amount of time it took to literally melt the wires running to it (oops) and totally drain the battery (oops).

This time I left the masking in place, painted it black, removed the masking (with trouble removing adhesive) then cleared it.  The adhesive removal step was fairly abusive and involved a torch.  (oops).  But it got it done, and although it didn't come out how I wanted, it still looks cool, has some character, and my mom loves it.

 

EastCoastMojo
EastCoastMojo Mod Squad
9/3/18 7:30 p.m.

In reply to ProDarwin :

Very cool!

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