Instructables
Needing a prototype done for a shaft encoder, Steveastrouk asked me to experiment with removal of paint on stainless steel using our laser cutter.

If successful the void in the paint could then be used to electrochemically etch the holes in the shaft encoder.

While not an instructable that's immediately accessible to a lot of people, hopefully you'll find the end result attractive and some of the instructions on prepping and painting metal useful. This instructable will hopefully serve as an introduction to several projects I'd like to publish over the next month.

Since shaft encoders are a bit boring, I also etched a graphic by HiddenPower, gmjhowe's logo and the hackaday logo to see how solid images looked as well as to give me a more interesting title image. I think they turned out great!
 
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Step 1: Tools & Materials

Picture of Tools & Materials
Tools:
  • laser cutter
  • bead blaster (optional, bead blaster not sand blaster since it's finer)
  • something to cut the metal with (bandsaw, hacksaw, tin snips, guilotine)

Materials:
  • stainless steel sheet (I used 0.6mm)
  • Plasti-Kote Woodstove Black
  • acetone (or other cleaner/degreaser... IPA, Flash, Limonene)
  • emery paper (if you don't have a bead blaster)

Sorry, there's no picture of all the tools in one place, getting the bead blaster, laser cutter and all the other bits in one place would be impossible! Instead, here is a picture of PKM, gmjhowe, Kiteman and Lemonie crowded around our laser cutter.

Step 2: Surface Preparation

Picture of Surface Preparation
Surface preparation is key here.

To get the paint to stick as well as possible, the metal should be clean with all grease removed from it. The surface also needs to be roughed up to give the paint more to stick to.

I first bead blasted all the sheets of metal I wanted to play with. This is to rough them up as described above, but also to remove all the crud and some of the grease. Don't have a bead blaster? No problem, some very fine grit emery paper should do the job just as well but take you a little longer.

To remove any remaining grease I squirted a tissue with acetone and wiped the sides to be painted, being careful to only hold the edges after cleaning. A kitchen cleaner like Flash would also suffice, as would IPA (isopropyl alcohol NOT india pale ale).

Step 3: Painting

Next it’s into an oven to warm the parts. The paint sticks better and gives a nicer coating if the metal is preheated.

Once warmed to your liking, spray the sheets in a well ventilated area.

Having sprayed them the parts can go back into the oven to dry. Drying takes about 2 hours in an oven and it helps to keep the dust off them while they're still wet. Alternatively leave them in a dust free place for 10 hours or until they're dry.

Step 4: Laser Etching

Once fully dry the painted stainless can be etched. I used a high power (98/100) , a high etch speed (300/400) and a step size of 0.1mm per scan. These worked better than the original settings I used since the thinner sheets of metal warped when I ran it at a lower speed.

The shaft encoder was designed in a CAD program called Alibre then exported into the program that came with our laser cutter as a .dxf file. This one took 2 minutes to run.

The logos I etched were imported as jpegs and the program sorts out the rest. They took slightly longer to etch since there was a larger area of paint to remove, 4 or 5 minutes.

Step 5: Results!

Picture of Results!
SDC11664.JPG
SDC11688.JPG
And here are some shots of the finished etched sheets.

Got a laser cutter and give it a go? Please post some pictures in the comments, it'd be great to see it done in some other colours, or perhaps layers of colours!
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Fantastic images, very clear, but I would have liked to know roughly how large/small they are...... I would guess for etching, you have to make a negative image, so that only what you don't want is removed....the gears appear to be free of paint, so you would have "gear shaped" holes......is that correct? How powerful is the laser itself (I am building a CNC machine) and what would such a tube cost? Roughly.... Many thanks for sharing. Regards Andy
Jayefuu (author)  der_fisherman4 years ago
The images I etched ranged from 3x3 to 6x6 cm.

Yes, you'd have gear shaped holes.

The laser cutter I'm using is a 40W HPC Laser Cutter. The tube by itself costs 195GBP.

http://hpclaser.co.uk/index.php?main_page=product_info&cPath=2&products_id=25
nerd7473 Jayefuu10 months ago

What is GBP?

Jayefuu (author)  nerd747310 months ago

Great British Pounds. Or £.

Sweet. I am envious of your Laser Fu.
L473ncy4 years ago
I know it's supposed to be an "artsy" logo but the first gear logo you have there just makes me cringe. The gears won't move..... Not only do you have an odd number of gears, but the three in the middle just won't move because they're locked together in place. That's just a thing that I'm a stickler about. Other than that looks pretty cool. Does it work on Aluminum and other metals (ie. really low grade "monkey metal" or pot metal)?
radiogareth4 years ago
Nice idea, I'm thinking of trying it on some cheap copper clad SRBP or some very thin flexible pcb that I've seen on here in other instructables. Opens up a huge possibility of ideas. (Custom LED light shades for instance) Easier and cheaper than using photo-coated pcb. You don't say how you then etched the surface? Not a lot touches stainless after all, and that which would might take the paint off too?
Would it work with metal that had been blued?
qqqqqq5824 years ago
I did this 3 months ago with pre-made etching metal, It was fun!
kill-a-watt4 years ago
Take a look at this pdf (from here).

Me thinks this could also be useful to create all types of prototype parts from sheet steel using a laser etcher that isn't powerful enough to be a laser cutter.
Jayefuu (author)  kill-a-watt4 years ago
That's the pdf I used to make my encoder :)
The technique is different.  He's painting large areas and then scratching  an outline for the parts he wants to remove.

You are painting the large area, and then blasting away large open areas to create designs. While that makes great HaD logos, it's a large area to electrochemically etch away.

Oh, and in the PDF, he's making a reed valve for a pulse jet engine, not a rotary shaft encoder.

It looks like you haven't started on the actual etching part yet, I thought the technique would be useful.
Jayefuu (author)  kill-a-watt4 years ago
Thanks. I etched it last week but have yet to document it or am unsure whether I should since he already gives great directions. The larger open area of the shaft encoder didn't seem to matter when etching, though I thought think it would probably be quicker if I just did the outlines.
Document it. If you pulled some good ideas from that guy's page, it would be nice to credit him.

The fact is that it's an obscure reference, and I don't think anyone has picked up the ball and ran with it beside you.

I've had the idea of making full moon clips for a S&W 610. It would be cool to actually scribe the design with a laser cutter first.

I also think this instructable needs a note somewhere explaining that while you are using a laser cutter, it can't cut through items like stainless steel because it's too reflective (I assume that is the reason why)
kelseymh4 years ago
Hey, so who's the hidden person between PKM and Laird Howe in Step 1? There are clearly five people in the picture, even if we can't see more than the chin and uppers of one of them....
It looks like a lady to me. LizzyAstro/Kitewife?
I would have guessed Han, as the mostly like to be willing to stand next to Howe. Notice in particular how The Teacher is keeping a respectful distance upwind :-)
Heee. Actually, I think you may be right. XD He IS rather far away from him, isn't he?
Jayefuu (author)  Lithium Rain4 years ago
It could be HiddenPower or Perryscope
Jayefuu (author)  kelseymh4 years ago
Not sure... can't see enough of them. Don't think it's Steve, there's not enough beard.
Sunbanks4 years ago
I absolutely love the one that HiddenPower designed!
Jayefuu (author)  Sunbanks4 years ago
Cool huh? I think it's going to be his tattoo design once it's finished.
That's so awesome :D
kcls4 years ago
That comes out looking really great! Nice job.
Kiteman4 years ago
I assume the circular-dotty-thing is the shaft encoder? That's a pretty cool image in its own right.

(And, dang, it was a surprise to see the photo in step 1...)
Jayefuu (author)  Kiteman4 years ago
Yup. You think I should use the disk as the title image?


Kiteman Jayefuu4 years ago
Yeh - maybe crop it a little so that all you see is the circle and nothing beyond the painted surface.
gmjhowe Kiteman4 years ago
I like his first image better.
Jayefuu (author)  gmjhowe4 years ago
You would do! It's your logo :p I added a cropped version on the shaft encoder. I like the hackaday logo best, but didn't think another website's logo would be suitable as the title image. What do you recon K? Shaft encoder or gmjampersand? :)
Kiteman Jayefuu4 years ago
I like the gear thing!

(And, isn't the actual "gampersand" looking a bit furry around the edges at the moment? Hardly laser-cutting standard...)
kcls Kiteman4 years ago
I agree, I was wondering about that.
Jayefuu (author)  gmjhowe4 years ago
How 'bout now?
Jayefuu (author)  Kiteman4 years ago
I decided to stick with the same image since I think I agree with jake, the encoder doesn't look that exciting. It's now cropped and rotated a little though. Thanks for the advice :)
kelseymh4 years ago
Very nice, dude! Not all Instructables have to be homebrew things, and this is well done. I am disappointed that you didn't have something to put on Step 2. Not even a picture of the bead blaster? Or maybe a macro shot of some of the beads, to compare to sand?
Jayefuu (author)  kelseymh4 years ago
I shall add a picture of the bead blaster (it's a scrappy looking thing, but don't tell Steve I said so) and the ultrasonic cleaner tomorrow before work. Thanks for the advise mike!

Scrappy is good -- makes it look like somebody actually uses the thing, instead of leaving it in the lobby to impress clients ;-> As for not telling Steve, I'm afraid it's probably too late, subscriptions and all, you know.

Jayefuu (author)  kelseymh4 years ago
How's that? Image tagged so you can see what each bit does. :)
That is awesome! There's enough detail in those tags to make it a whole little bead-blasting I'ble of its own :-)
Jayefuu (author)  kelseymh4 years ago
Just found a better title picture too :D I think.
MegaMetal84 years ago
very good 5*
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