ValveLiTzer Redux

Step 6 Etch the Aluminum Plates

To mark the jack, switch and potentiometer functions I etched the board using electrolysis. The rough, sunken labels contrast nicely with the polished plates. They're also permanent - no amount of use will wear them off.

You will need to construct a simple electrolysis etching tank. There are plenty of Instructables on how to do this, so use one of them if you like.

I used a 2 liter ice cream container filled with warm water and a few tablespoons of table salt (NaCl). Note that if you use regular salt, chlorine gas may be produced during the etching process. Washing soda is a great alternative to table salt and I recommend you use it instead, especially if you have to work indoors. You will need a second plate as well, at least as large as the aluminum plate you'll be etching. It should be made of aluminum.

To power the etching tank, I used a regulated power supply. You can use the same, or you can use a converted computer power supply or a car battery charger. Anything that puts out +12V DC with at least an amp of current will work.

Before etching you'll need to transfer the patterns to the aluminum plates. I used the laser printer on photo paper method. Print the letter stencils in reverse on a laser printer, using glossy photo paper. Make sure the image is good and dark. Cut out the stencils with a 1/4" margin, and write the stencil name on the back of each piece to help keep track of them.

*** If the text doesn't show up properly, you'll need to install the font I used: Blue Stone

Lay out the aluminum plate on a heat-resistant surface, and place the stencils in the correct positions. Now, with an iron set about medium-high with NO STEAM, fuse the stencils onto the metal. Note that as the metal gets hot, the other stencils that you haven't touched yet will want to fuse to the metal all on their own. Either prevent them from moving, or do just one at a time.

The stencils should transfer completely, with no toner left on the photo paper. It took me a few tries to get it right. You can touch up small errors with nail polish (yes, really) but for big mistakes you'll have to scrub off the toner and do it again.

The last step before etching is to cover up the rest of the plate, so that it won't etch. I used packing tape to cover every surface - front and back - that I didn't want to etch. Leave a small unexposed corner at the top to clip an alligator clip onto.

This process is different than electrolytic rust removal. In this case, attach the red (+12V) lead to the plate being etched, and the black (ground) to the second plate. With everything hooked up, turn on the power. This process takes just a few minutes. Soon the water will start to get hot and bubble like a witch's cauldron. Remove the plate every minute or so to check on the etching.

When you're satisfied with the amount of etch, turn off the power, wash the aluminum plate in water, and peel off the packing tape. Then, scrub off the toner with rubbing alcohol. It takes a bit of elbow grease to get it off!

Comments

[tewfik]

thank you for the instructable i'm trying to etch a smd stencil from aluminium and this is getting me crazy could this method be used to etch, say, about .5 mm holes ? the board is approx .1 mm thick, i ve tried the ferric chloride so far, but the etching is very not so precise

[jeff-o]

Hmmm, it might work. I haven't tried etching holes straight through aluminum before, though. I think the biggest problem you'd run into is that the edges of the holes might be a little jagged, due to undercutting. Can you cut a smaller piece of aluminum and do a test to see what kind of precision you can get?

[gabrielG2]

you can use Thinner to take the toner off, it's almost instantaneous

[jeff-o]

Cool, I'll try it next time I use this method.