"rangerssuck" wrote in message
...

On Tuesday, December 13, 2016 at 10:59:13 AM UTC-5,
wrote:
On Tuesday, December 13, 2016 at 10:53:51 AM UTC-5, rangerssuck wrote:
I am making prototypes of a new product. The case is made of aluminum
plate, approximately 4" x 1" x 3/16". I have engraved a test piece and
it worked very well, but:

* Due to the complexity and fine detail of the engraving, I can only go
to about .0005" depth with a .1mm x 10° bit.

* Doing this on bare aluminum, it has all the detail, but very little
contrast. I would like to color either the whole piece and then etch
through to bare aluminum OR color the design after engraving.

* All I have read about coloring after engraving recommends a minimum
depth of .005", preferably .010 - .012". That would not work well for
this design. I tried rubbing in some acrylic paint, waiting for tit to
dry and rubbing it off, but it also removed most of the paint from the
design. I also tried squeegeeing off the paint, with similar results.

* I'm not even sure that black anodizing beforehand would work, as (I
think) the anodize layer is thicker than I am engraving.

So, I started looking at other coloring methods for aluminum. The one
that keeps coming up is Birchwood Casey Aluminum Black Metal Finish
https://goo.gl/zfC1eo . The reviews are mixed for this. Some say it's
great, others say it comes out blotchy and still others say it barely
colors the metal. Brownells also sells it.

I'm thinking that I could either color the entire piece and engrave
through it OR spray a coat of paint on the whole piece, engrave through
the paint and then use the Birchwood stuff (or something else) to color
the logo, and then strip off the paint.

I welcome any suggestions and experiences.

BTW, I'm doing this with a newly acquired Taig cnc mill. Very cool, fits
my needs well. From this engraving test, I see no reason why it won't
work fine for making prototype pc boards. Sp many toys, so little time.

JPB

Regarding the reviews on the Birchwood stuff, different grades of aluminum
respond very differently to anodizing and chemical treatments. That could
be the issue.

--
Ed Huntress

The plate I have (left over from another job) is 6061.

Right now, I'm trying a different approach. I flooded the area with india
ink, and I'm baking it at 180°F to dry it out. When it cools, I'll try
sanding it off with 600 grit paper on a flat plate. I just took a peek in
the oven, and it looks very nice, the ink has flattened out, and the
recessed pattern is quite visible. I'll takeit out and let it cool in a few
minutes.

I have to say, by the way, that SWMBO is taking this extremely well -
supplying both the ink and the oven.
================================================== ================================================== =

No direct experience, sorry, but a suggestion. Have you thought about silk
screening instead of engraving? It is easy and pretty cheap to do at the
one or a few level, and the paint is pretty durable. An old co-worker used
to silk screen all the front panels of his prototype electronics projects,
and watching him it seemed pretty simple. Also, maybe the paint itself
would work better than india ink to fill your engraving, then bake and sand.
Just a thought.

-----
Regards,
Carl Ijames