Introduction: Laser Cutting Flat Enamel Forms
I've been doing a lot of enameling lately, and I've also been doing a lot of laser-cutting. I decided to see what would happen if I tried to laser-cut some enameled copper; here I'm sharing the process and results. Overall, laser-cutting enamel can be quite unpredictable, given the different chemical make-ups of different types of enamel, in addition to other factors, like the number of layers of enamel, and the thickness of each layer. But the potential outcomes can be really interesting, and this Instructable should serve as a starting point for anyone who wants to set out on this journey.
In this Instructable, I'll show you the start to finish from a flat sheet of copper, to the creation of a die for shaping multiple identical hexagons in the hydraulic press, through the enameling process, and laser-cutting, and then touching up/treating the laser cut tiles with graphite, and re-firing. Many of these steps could use their own Instructable - some of them already have relevant Instructables done by others, and I'll include links when possible.
On a side note: I thought it would be best if I embarked on this project with a particular goal, so I decided to create a customized Hive set. I really like Hive, but I'm not too fond of insects, and I wanted pieces that had tri-lateral symmetry so that the way they were facing wouldn't confuse newcomers to the game. There are a couple of other really amazing Instructables on laser-cutting Hive sets, but they use acrylic and wood, neither of which has the nice heft of the Bakelite tiles of the original game; enameled metal begins to have that satisfying weight.
On another note: This project contains all manner of dangerous operations - we've got acid, fire, knives, saws, lasers, and the potential for high-speed flying steel. Please protect yourself accordingly - safety glasses and close-toed shoes at the absolute minimum.
Step 1: Laser-cutting Our Acrylic Template for the Hydraulic Press
If you've never used a laser cutter before, you should take some time and read the basics. This Instructable is a pretty good intro. I'm going to be using an Epilog Helix 40W laser, Adobe Illustrator to generate the vector file, and I'll be cutting the template from 1/8" acrylic sheet. 1/8" acrylic, in tandem with our steel (next step) will give us a shallow hexagon with a bit of curve that will be the perfect depth for taking enamel and laser cutting. If you'd like, you could use thicker acrylic, though I wouldn't use thinner.
I want my enameled hexagon tiles to be the same size as the original Hive pieces. These are 37mm from edge to edge, or 1.46 inches. Illustrator draws its polygons from corner to corner rather than from edge to edge, so a quick way to get the right size would be draw a hexagon of any size using the polygon tool, then draw a straight line at 90 degrees that is 37mm, and resize the hexagon to the size of the line.
Next, I'll draw a square perimeter centered around the hexagon. At its narrowest point (at the hexagon's middle vertices) I want this square to be about a half-inch from the hexagon. This will be the overall size of our template. A square that's around 2.75 inches will work.
Finally, I'll change the stroke width of the hexagon and square to .001pt so that the laser cutter will read this as a vector file, rather than a raster file, and will cut rather than engrave the acrylic. I'll then position this shapes in Illustrator, and set up my acrylic on the cutter bed. I chose to position the shapes in the upper left corner because I've already cut out from my acrylic, and I know I have a clean spot in the upper left.
In order to cut the acrylic, I'm going to set the laser cutter's power to 95, speed to 12, and frequency to 5000 (the max). I'm also going to turn on the ventilation full blast - acrylic is safe for the laser to cut, but it smells strong, and is not ideal to breathe. Finally, it's time to fire the laser!
Step 2: Cutting the Steel for Your Hydraulic Press Die.
I've been strongly discouraged from etching steel on my university laser cutter, so I'm going to use my laser-cut acrylic template to mark a pattern on my steel by hand. I've already cut down some mild steel (20 gauge) to match the size of my template using a bench shear. Barring access to one of those, you could also use some hand-shears, or a jeweler's saw if you're patient.
Next, I'm going to position the steel square in a bench vise, with my cut acrylic square in front of it. I'll use metal dividers, but you could use any hardened steel or diamond tool to scratch the cut hexagon into the steel.
Then, I'll drill some holes into the hexagon to provide a starting point for a jeweler's saw to cut. I'll use a metal punch and a mallet to knock three impressions into the interior of the hexagon, which will give the drill bit a point to nest into. Then I'll bring it over to the drill press. I know that my jeweler's saw blade is size 3/0, and I need to drill a hole that will accommodate that; looking at this chart, I can see that that's a size 76 drill bit.
Once my holes are drilled, it's time to cut! Cutting metal with a jeweler's saw can be frustrating for beginners - you will most likely break a whole bunch of saw blades, so don't sweat it. You may want to check out this tutorial for beginners.
I find it easiest to cut out the center triangle first, and then work to the edges of the hexagon so that I have less metal on either side of the blade. I'm also careful when turning at each of the vertices - I'll move the saw up and down while rotating, but not move the blade forward, in order to give the blade some space to move. Even with all that, my steel die isn't perfect, but in tandem with the laser cut acrylic template, it will still give a great impression. So I'll use some double-sided tape to stick them together. The combination of 20-gauge steel with 1/8" acrylic (plus the slight thickness of the tape) will help us achieve relatively flat hexagons with a bit of depth - these will hold onto the enamel really well, without requiring too may layers to fill.
Step 3: Preparing Your Copper for the Press
Now it's time to cut out our copper. As with the steel, I used a bench shear, but barring access to that, you can use some french shears or a jeweler's saw (the copper will be easier to cut than the steel). Precision is not so important here - as long as your copper comfortably fits within the confines of the square of your hydraulic press die, with enough of a lip outside of the hexagon that it won't get sucked in, you should be fine.
The beauty of this process is the relative ease at making multiples. I'm cutting and prepping about 30 copper squares - I figure this will give me enough for the 22 base tiles for a game of Hive, with plenty extra for enamel samples and a few mess-ups.
Next, I'm going to anneal my copper. Because using the hydraulic press is strenuous for the copper - I'm shaping and stretching it - I want to make sure that the copper is nice and soft before I begin. Annealing softens the metal, spreading apart the molecules so that the metal can be worked further. I spread out as many pieces as I can into my annealing tin, and heat them with a torch until they just start to glow red. Using tongs (the copper will be hot) I'll then pick each one up and quench it in a bowl of water to quickly dissipate the heat.
Finally, I want to clean my copper in some jewelry pickle in order to get rid of the fire scale that comes about when the metal is oxidized from being torched. Here is an Instructable on a DIY pickle solution, and here is a link to a more commercial solution (which is what we already have prepared in our metals studio). Either way, I'd recommend the slow cooker, as the low heat will greatly increase the speed at which your metal is cleaned. Jewelry pickle works because it is acidic. More natural pickle is probably a bit safer, but acids will eat through your clothes, and can stain/burn your hands, so use tongs, and rinse everything after pickling.
And here we have our metal all laid out to dry! 30 squares of copper: cut, annealed, and ready to press.
Step 4: Forming the Hexagons in the Hydraulic Press
Forming metal properly in the hydraulic press is an art unto itself. For a more thorough explanation, check out this great embossing tutorial. There are also a number of Instructables on building your own affordable hydraulic press, which may be a worthy investment if this catches your fancy. For now, I'm using the hydraulic press in my university jewelry shop - it's a little ramshackle, and the pressure gauge doesn't really work, but it will do the trick for now.
The hydraulic press consists of a lever, which, when cranked, raises the floor of the press to meet the ceiling of the press, with many tons of pressure. Whatever is between the floor and the ceiling at the point will be compressed greatly, and this is how we will form our copper.
So, we're going to load a carefully composed sandwich into our press. Throughout this entire process, we want to keep everything as centered as possible - this is tons of pressure that we're talking about, and if things are off-center, the pressure can actually cause bits of the sandwich to shoot out at incredibly dangerous speeds.
-The bottom of the sandwich is a lucite square - this is just a spacer so we don't need to crank as much to decrease the distance between the two sides of the press.
-Next, we'll put our acrylic and steel die onto the square, with our steel on top. The steel is what's going to press into our copper to give it shape, and the acrylic provides a bit more space for the copper to move as its formed, to give it some more depth.
-On top of the the die, we'll place our copper - take care to center this as well - any edges that are inside the hexagons instead of outside its border will get pulled into the die when we press, rendering our hexagon imperfect, so we want to keep this as even as possible.
-On top of the copper, we'll gently place a sheet of soft urethane rubber, taking care not to offset our copper or die in the process. Urethane rubber can be purchased for a variety of purposes, but if you search for hydraulic press urethane, you'll turn up what you're looking for. The soft urethane that I'm using is about a half-inch thick - because its soft, it will deform and compress a lot under pressure, forcing itself into the hexagonal space in our die, and pushing our copper with it - this it what forms the copper.
-On top of the soft urethane, we'll place a sheet of firmer urethane - this is thinner, about 1/8" and will give us a little more definition in forming the copper.
And that's our sandwich! It's time to crank the lever on the hydraulic press to apply pressure. Because the gauge on this press is broken, I'm going to judge when to stop by feel and by the appearance of the urethane outside of the press. When it becomes unreasonably difficult to apply more pressure, and I see the urethane starting to deform, it's time to twist the valve, release the pressure, and unload our piece.
And there we have it - a rectangle with a perfectly formed, rounded hexagon within! Now let's do this a whole bunch more times, cut these out, and prep them for enameling.
Step 5: Cutting Our Hexagons Out and Prepping for Enameling
I'm using some French shears to cut out the hexagons - because the copper is so thin, this is pretty easy. Once their cut out, I'm going to put them back into the pickle. Though the hexagons won't have oxidized as much as when they were annealed, they'll have picked up some oil from your fingers as you handle them, which will make it difficult for the enamel to stick - you want them as clean as possible. Also, if you've waited a couple of days to do this since you last pickled the copper (like I did), they will have oxidized somewhat, and pickling will be a good thing to do.
Step 6: Enameling
Enameling is the process of bonding powdered glass to metal (sort of like a ceramic glaze) - this glass is what we'll be engraving on our laser. This step is also where I'll leave you to fend for yourself. As with the hydraulic press, enameling is an art unto itself - some college metals programs will spend an entire semester on enameling. But, for starters, here is a great intro to firing enamel with a torch. And once you understand that, here is a pictorial demonstration of the same process, with a kiln. Kiln-firing enamel is faster and easier, but kilns are expensive, and use a lot more energy. I have a kiln set-up in my metals shop, and so this is how I'll be firing the enamel.
You'll want to do two layers on the convex/outside/non-hollow side of your hexagons - this will keep the copper from oxidizing every time you put it in the kiln. And you'll want to do as many coats as necessary to fill the hollow side of your hexagon - it took me 5-6 layers, firing each layer.
The chemical compound of your enamel will affect how it is engraved on the laser, and so this is where the multiple hexagons come in handy - you may want to try out a whole bunch of different enamels so that you can make some samples. Personally, I used Thompson 1040 Quill White, and Thompson 124 Black Hard Fusing, for most of my hexagons, as well as a medley of other colors and layers just to try things out.
Step 7: Laser-cutting Our Jig
As our goal here is to set up a readily repeatable workflow that can be applied to many enameled hexagons, our next step is to create a jig into which we can set our tiles - this will ensure that we place the tiles in the perfect position for laser-cutting each and every time.
Do you remember the hexagon that we made before for cutting our template out of acrylic? We'll need the same thing again, except this time, we want a black fill in addition to a .001pt black stroke. This way, we will be able to use the laser to cut both vector and raster, slowly engraving the shape of the hexagon, while also cutting the walls each time, thus making the space slightly bigger so that our hexagons fit snugly. Hold onto that hexagon file! This is how we will place our pattern for laser-cutting when our jig is finished.
Next we'll want a block of wood that we know is square in one corner - this way, it can nest neatly into the corner of the laser cutter, in the same place each time, and even if it moves, it will be easy to re-position. The block I used is pretty small - just about 3.5" by 7," but it's Baltic birch, and about 3/4" thick, so it has a good weight and won't move very readily.
We'll want to take multiple passes off of the wood to slowly create the impression in which our tile will sit. I have my laser set to 100 power for vector and raster, 50 speed for vector, 40 speed for raster, and 2500 frequency for vector. My tiles are about 1/4" thick with all of the layers of enamel on them, and it took me about 4 passes till a tile could sit comfortably without moving in the impression. As layers of wood are cut away, the distance between the surface of the wood and lens of the laser will increase, so you'll want to raise the bed accordingly. I did singe the wood slightly in the process, but as you can see, the tile still fits really well.
Step 8: Laser-engraving Our Enameled Copper!
We're finally here! It is time to to engrave our enamel. Two critical notes:
-Enamel is glass and it is very shiny and reflective, which means it can reflect the laser causing a lot of damage. Therefore, make sureto cover your piece with a layer of wet paper towel before engraving! This will prevent damage from the reflection. If you engrave multiple passes into the enamel, you'll want to put a new piece of wet paper towel after each pass.
-Enamel is glass. Depending on how you engrave this glass there might be sharp splintery bits that are generated in the process so be careful.
We're going to take the hexagon from our vector file that we used to engrave our jig, and use that to position our laser-cut patterns - this will ensure that we are engraving precisely onto our enameled tile.
Now - here are some base settings that work pretty well, though you may want to adjust these depending on your success with different colors and kinds. Make sure that your laser is focused properly - ideally the surface of your enamel is as uniform as possible, but the distance should be to the highest point on your enamel (if the lower points are a bit too low, they will still engrave, but will be fuzzier and less-defined). You may need to do multiple passes if your enamel is not even, replacing the wet paper towel each time.
-Vector: 5000 frequency; 100 power; 75 speed
-Raster: 100 power; 45 speed
Vector will produce a fairly crisp mark, that will range from burnt black to toast brown to a colorless engraving. Raster will give a frosty appearance to the enamel, and is also more likely to create glass splinters.
Re-firing the enamel afterward also has mixed results. I tend to find that the darkening vectors remain after a firing, the colorless vectors are a mixed bag, and the raster engravings tend to go away. But realistically, if the glass has gotten splintery, you'll want to re-fire the enamel to smooth it out. One way to resolve this is to take a pencil, and run it over the rough, laser-engraved areas, then clean it off of the smooth areas. Graphite (pencil lead) can fire really nicely into enamel, and this is a way to preserve the laser cut marks. Again, this greatly depends on the quality of your laser engraving - as you'll see in my photos, I've had mixed results, ranging from crisp lines, to child-like pencil drawings, to partially faded curves.
And there you have it! Please let me know about your own successes with laser-cutting enamel in the comments. It's an unpredictable process, with some pretty amazing possibilities, and I'm excited to see what you can achieve!
I'm attaching the Illustrator files for the Hive tiles that I designed. Remember: you can use the hexagon surrounding each of the tiles for placement for the laser cutter, but don't forget to remove the hexagon before sending it to engrave or you'll want up with an extra engraving step which could mess up your edge. Good luck!