Introduction: Scrap Metal and Lasers: Cermark'd Keychains

With many members making projects at TechShop, there is almost always a bountiful supply of scrap materials whether it is metal wood or plastic. (And everything in between). When looking through such a scrap bin I found a handy piece of scrap metal that left plenty of room for various projects. While it was rusty, it was an insignificant obstacle when using the tools at TechShop San Jose. In combination with Cermark laser marking solution, I could use the sheet steel as is without worrying about finishing first. In the Laser Safety and Basic Use class here at TechShop, the basic project is always an anodized dog tag; I thought it would be nice to switch it up a bit and mark it black instead of metallic. 

For this project I used:
  • Random Scrap Metal
  • Nitrile Gloves
  • Safety Glasses
  • Angle Grinder (With Flap Wheel)
  • Bench Grinder
  • A Hammer
  • Straight Hand Shear
  • Rotex Punch
  • Deburring Wheel
  • Simple Green
  • Cermark Laser Marking Spray
  • Epilog Laser Cutter and Engraver
The classes required for this equipment are: 

Step 1: Prepping the Metal

As pictured, The metal I found was in a rusty state which definitely doesn't work for Cermark to work effectively. This is an easy fix. Using a clamp and an angle grinder with a flap wheel, you can give the metal a slightly polished surface which complements the end product! For this step be sure to where safety goggles or a face shield because sparks will be flying. Since this is a rotary tool, I would definitely advise against using gloves. In addition, if you are going to be working with aluminum, the material will clog the grinders unless they are specifically for the metal.

Simply clamp the metal to whichever worktable you want, but be sure not to over tighten otherwise it will likely mark up the surface too much. Here I would also flatten out the piece, if needed, with a soft-ish hammer. This will make things easier as the project goes on. Once that is done, that's all that is needed to begin resurfacing. Turn on the grinder and go at it! Be sure to keep in mind how this the material you are grinding is since heat will build up. I did not keep this in mind until I accidentally ground through one spot on the metal.Beyond that, just flip over, re clamp and do the second side as well. The newly finished sheet is now ready to be shaped!

Step 2: Shaping the Metal

The go to shape is typically a dog tag but you can do anything you want. The tools are simple and pretty straight forward. For the rough dimensions, I took the sheet metal to the straight shear. It will easily handle material up to 16 gauge and will cut perfect as long as the material is positioned correctly. Once I got roughly the rectangular size I wanted, I took the metal to the rotex punch to cut out the proper sized hole (for a keychain). These two machines will do the basic sheet metal work and the rest is done on the grinders.

With this step, be extremely careful. The pieces of metal you are now working with are really small and your fingers are close to the spinning wheels. This being said, don't be tempted to wear gloves. If you do and your fingers do make contact, there is a possibility of de-gloving yourself which will be much worse.

With shaping the metal, I could have had a set pattern to follow or a set dimension to abide by but I wasn't really feeling that. Besides, if I made some pieces longer or wider it would open up possibilities for different designs when the tags are taken to the laser. As part of this, there was no specific curve I followed when shaping, I just did whatever looked good. Essentially, I held the metal against the small table in front of the wheel for support (so it didn't catch and pull in, safety and all that), and moved the metal in the curve shape. In the pictures you can see the before and after. This is essentially what I did for every corner on these soon-to-be keychains. As with the flap wheel, be careful of how much heat is building up and be sure to cool the metal in water frequently. Before too long the wheel can burn through the metal and the heat build up can burn your fingers.

The grinding process however, leaves burrs on the edges of the metal. If you intend on giving these as gifts, or even if you don't, you'll want it to be free of any sharp edges to make sure they can't catch on any fabric or accidentally cut the user. This process is taken care of by the deburring wheel! Mounted on a bench grinder, this porous wheel will slightly polish the metal as well remove any edges that are present on the surface. (An example of this is also pictured.) 

With this done, it is now time to clean the surface and apply the Cermark.

Step 3: Cermark Application

In order for Cermark to work properly, the surface on which you wish to apply the spray needs to be free of all dirt, grime and oils. The flap wheel took care of the first two, but since gloves were not worn the metal is covered in oil from skin. Thankfully, a commonly used  cleaning substance such as Simple Green also acts as a degreaser so this step is easy as well. While wearing nitrile gloves, spray the surface with simple green and lightly scrub and wash the surface to rid it of the oils. Dry off the metal quickly with a towel, just to firmly discourage new rust appearing.

From this step onwards, it is wise to wear gloves the entire time as to not to get oils back on to the surface.

Once the tags are dry, the newly fabricated keychains are ready to be coated with Cermark! The instructions on the can state that it needs to be shaken for at least two minutes before applying. This is actually important! Since the substance itself has its base in ceramics, it is much easier for the contents to settle and separate. If you stay true to the 2 minutes as close as you can the results you will get will be much more even and as a result much nicer in the end. It only takes about 5-10 minutes for the spray to dry, and I documented the slight color change that occurs after it has dried.

While the Cermark is drying, figure out what design you want to apply and prep the file!

Step 4: File Preparation

For this step, rely on the text that I wrote in the images above. It's a fairly simple process that can be applied to many other laser project. If etching an image on something, at least when it isn't glass, is better if black and white. In either case, the higher the contrast the better off you are.

Image Source
ooperblooper22 on Deviant Art

Step Text:

Step 1
This is the image I started with, a sprite layout for Space Invaders throughout the years. I have sourced this image in the text below. 

Step 2
To begin, choose which sprite you want, zoom in and crop it from the picture.

Step 3
Duplicate the background first. CTRL-J [while selected on the layer]
Then once you have done that, while selected on that new layer, select the background of the image using the quick selection tool. After you have done that, erase what you have selected.

Step 4
If you want to see the results, to the eye off on the background layer.

Step 5
Once the background is gone, use the paint bucket tool to change the color of the sprite. The laser will etch whatever is black/shades of grey. With whatever you decide to etch, the closer to black and white the image is, the cleaner it will look. 

Step 6
From this point onwards, you are essentially done! The program I used to print to the laser is Adobe Illustrator and so I just did the final design work there. That final work being, measuring the dog tag and imputing the dimensions for the artboard. This will make it easier to center and line up with the laser to ensure maximum quality. 

Step 5: Lasers and Finishing!

With both the metal and the file ready for the project, you are now good to go for the lasers! 

After a couple of tests on the same metal, I finally dialed down the settings to 90 power and 10 speed on one of our cutters. However, since these machines get so much use don't depend on these settings to be perfect, the power can change from week to week as the machine wears down and receives maintenance. What you are looking for, is a solid black surface across the entire area of the design. You may notice some patching as it is etching and that is incorrect and will wash off when you go to get rid of the excess spray.

To finish the process, all you need to do is take the finished keychain to the sink and rinse with warm water. I don't recommend scrubbing, as it may scratch your finish unnecessarily. With just your hands is fine, all of the solution should come off and end up looking like the final product as featured!