Tag Archives: rounded edges

120: Fluorescent Samurai FightStick

Somehow for all the plans I’ve had over the years to laser engrave a fight stick, I never actually got around to it until this week! Last week, a coworker at the library was planning on making a custom artwork label for his arcade fight stick in the library’s makerspace, and it didn’t take long discussing materials and fabrication processes (including just printing on paper to replace the stock Ryu artwork) before I practically demanded to laser engrave the hardware myself. Since I kind of stole his project from him in order to complete one of my own, I hope there’s enough juicy details herein to cover the process! Thanks, Mark!

The stock acrylic has a lip almost certainly CNC milled. These aren’t easy to recreate with a laser!

We briefly discussed engraving the acrylic panel that is included with the controller, but we decided against that so that he’d always have an unaltered panel handy. Besides, we were already talking about using a fluorescent orange acrylic that we’ve used in the library before for making bright, eye-catching tokens and trinkets. It’s a fiery equivalent to the green acrylic I use for Ingress badges; edges practically glow with this material! But the material we chose was only available in 1/8″—about 50% thicker than the stock acrylic—so I’d have to do some measurements to make sure it’d still fit. There were a few other tricky issues to figure out as well, so I knew I had some prototyping to do. But first, the design itself!

The layout is about 13″ by 8″, features eight buttons and zero button labels. Pro!

Mark had already done some of the hard work and whipped up a layout of the artwork he wanted to engrave. It was only roughly the size of the fight stick’s acrylic cover. Featuring an illustration of a kneeling samurai and seven bushido virtues, he told me he’d always been enamored with samurai and the code they lived by.

“How that warrior code and Buddhist philosophy can coexist interests me.  … I think anyone who is interested in an applicable ethic for living, who understands that the world can be violent, but hopes not to have to actually be violent, will find plenty to study in the samurai.”

The layout didn’t have accurate measurements or the button and joystick layout, though, so I’d have to see if someone put one together online. As it turns out, we didn’t need to rely on the community; late product manufacturer Mad Catz provides a PSD template for users who want to print out their own art. Its pixels are no good for laser cutting, but it has the exact dimensions and throwing together some vector circles where the PSD says they should be was quick and easy.

The chipboard prototype fit perfectly, and looks pretty snazzy on its own!

Once I had the layout prepared, I ran several prototypes. The first was cut out of cardboard, which was slightly too thick to be used easily in place of the acrylic, but it did help me discover that I accidentally nudged the bottom row of buttons out of alignment when creating the vector template. I corrected those issues and cut out a second full size prototype in chipboard. The chipboard fit perfectly and even looked pretty good under the stock acrylic!

Several small material setting prototypes. Please ignore the Triforce!

I had to run several small engraving tests on the actual material because of a few techniques I planned to use that need really precise settings. First, I’d need to recreate a lip on the entire outside rim of the acrylic; I’d have to engrave very deeply in order to do so. I also wanted to make sure I created a nice depth effect on the engraving, so I’d need to combine the halftone raster engraving on the greyscale samurai art with selective vector engraving on the darkest strokes. Finally, because of the thicker material we’re using, I wanted to round the edges so they wouldn’t stick out quite as much around the buttons. This involves pulling the laser out of focus, so I’d have to make sure the depth offset was an appropriate amount.

Detail of the letter engraving, including the deep vector stroke outlining the glyph above.

During this prototyping, I figured out that I’d need to engrave at 100% power, 10% speed to burn away enough material to recreate the stock acrylic’s outer lip. That’s ridiculously slow, and across an entire 13″ by 8″ design it would have taken over three hours to engrave, so I ended up breaking the engraving into four jobs. By doing so, I prevented the laser from passing by the entire inner area of the acrylic, reducing the engraving time to about 35 minutes. What a relief!

This acrylic really shows off fingerprints, doesn’t it?

I also determined that pulling the laser out of focus by exactly 1″ creates a nice rounded effect while being a nice easy number to remember. I used the same settings that would cut through the material with the proper focus. The slight misalignment of my #2 mirror struck again and required me to move the out-of-focus vector lines just a tiny fraction to the left to compensate. One of these days I’ll get that fixed.

My final acrylic lip was close enough, and check out that smooth rounded corner on top!

After I engraved the lip and cut out the button holes, I flipped the material, removed the back face’s protective mask, and got to engraving the art! It might not be obvious at first, but if you’re going to engrave something you’ll be resting your hands on often, you should engrave the back face and leave the top smooth and untouched. Otherwise the engraving might irritate your skin and you’re going to have to clean your filth out of the artwork more often than anyone should have to deal with. Besides, the fluorescence of the material is best shown off through the material; back face engravings capture much more of the color and appear less frosty.

Samurai on metal plate. Great shadow effect, but with plenty of distracting screws.

Amusingly enough, it didn’t dawn on me until I installed the fight stick that I’d need to make some kind of thin black background layer so that the metal button plate wouldn’t be visible through the design. It’s kind of a neat look, but it detracts from the theme, so I used the only material I had on hand (some black/silver LaserLights; don’t tell Jen!) and cut the template out of that. It fit just fine beneath the acrylic, so it was time for put Mark’s fighting game weapon of choice back together for good.

One small detail: the acrylic’s rounded corners needed to be about 0.1″ radius, quite a bit rounder than I first estimated.

The final piece was simple to install thanks to the hinged design of the FightStick-branded fight stick (that’s not confusing at all, right?). I was a little worried that the originally-pencil samurai design would suffer from being printed “in reverse” (i.e. light lines on a dark background), but the way the deeper vector engraving works with the light halftone raster engraving almost makes it look like our calm, kneeling samurai is fashioned out of fire rather than graphite. As mark put it, “Simultaneously peaceful and ready for battle.”

The joystick just barely fits between the samurai and his blade.
Detail of shallow halftone raster engraving combined with deep vector engraving.

115: Rounded Edges

One of the first limitations of laser engraving I learned about was the right angle. On most (if not all? let me know!) laser engravers, the laser can only fire in one direction: straight down, perpendicular to the surface plane. This means that you can’t easily get beveled edges, rounded corners, or other nice depth effects you can get using a rotary engraving system like a CNC mill.

There are ways around this limitation, of course: a patron I spoke to at the Aurora Public Library‘s Makerspace suggested rigging smaller pieces of material at their own angles, allowing the laser to fire directly down at a skewed surface, creating the angled edge desired. I considered this process, but it only works if you are cutting a single straight line—any shift in the direction will pull the head out of focus with the section of material you’re cutting.

Focus matters, though, as I found out several months ago while cutting some badges for an event. I accidentally left the laser bed way out of focus when cutting one of these badges, and you can see how the laser didn’t cut through, and instead just created a rounded channel in the surface of the material, in the shape of the badge I’d intended to cut. It made me realize I could cut a shape normally, and then cut it again out of focus, to give the edge a soft curve.

The mistake that taught me how to round corners via unfocused engraving.
The mistake that taught me how to round corners via unfocused engraving.

So this month, I got around to testing that some more! I opted for some snowflake designs (sourced from freepik.com; thank you!) to give me plenty of edges to smooth and for general holiday goodness. The first step is to cut the piece normally, which results in the traditional sharp 90 degree edges you see in most lasered pieces.

Sharp 90 degree edges, standard for laser cutting.
Sharp 90 degree edges, standard for laser cutting.

Leave the leftover material in the laser bed, and do your absolute best not to disrupt its place. In fact, I suggest not touching the piece at all at this point and just telling the laser to fire again with new settings. Specifically, I threw the laser out of focus by telling it I was engraving on a 1.125″ thick material rather than a .125″ thick material. I’ve experimented with different unfocused settings, and can probably dial that in a little better, but 1″ is a nice easy number to get a decently rounded corner on a 2″ lens. I also sped up the laser a little bit because I didn’t want to overpower the edges when rounding them (while my speed settings won’t match yours exactly for a multitude of reasons, I cut the snowflake at 5.5% speed and then rounded the edges at 15% speed.)

The top side is now rounded; it's an imperfect process and looks a little rough up close.
The top side is now rounded; it’s an imperfect process and looks a little rough up close.

Since the rounding only happens on one side, you’ll have to flip the piece and round the edges again if you want to give both surfaces the same treatment. This is only possible if your piece has an axis of symmetry, and this is where you have to be very careful not to move your temporary jig. Once you’re done, you might have to clean the piece as firing a laser out of focus can produce a fair bit more detritus than firing it in focus.

Make sure to clean your honeycomb first, and wipe down any residue between each step. Oh, and use a clean cloth! Trust me!
Make sure to clean your honeycomb first, and wipe down any residue between each step. Oh, and use a clean cloth! Trust me!

As it turns out, even if you don’t move the makeshift jig at all, your second pass might be slightly out of alignment to the first. Why is this? Kerf—the width of the laser—means that your freshly cut snowflake might shift a fraction of a millimeter inside the jig. There’s a tiny, tiny little bit of give and it can sometimes be enough that the alignment is visually off. You can solve this by rounding one side before cutting, but you’ll still have to contend with this on the back half, and kerf didn’t affect my alignment nearly as much as another issue:

Much more alarmingly, I discovered while doing this project that pulling my laser out of focus by about an inch noticeably moves the laser’s aim. It’s not enough to ruin the project, but it is enough that I had to correct for it after several prototypes to get a nice even rounding. This aim issue as the laser focus changes is due to incorrectly calibrated mirrors somewhere along the laser’s path (totally my fault, as I foolishly adjusted them once upon a time and have been tweaking them here and there ever since) so if your mirrors are factory aligned like they should be you shouldn’t run into this issue.

Even if you don't move the piece at all between steps, kerf or poorly calibrated mirrors might cause your rounded edges to be misaligned.
Even if you don’t move the piece at all between steps, kerf or poorly calibrated mirrors might cause your rounded edges to be misaligned.

In the end, the rounded edges are a little rough looking, but if you get your settings dialed in (or would it be dialed out in this case?) you can get a nice smoothed edge that will catch light in a novel way for a laser cut item. I used opaque and translucent acrylic for this project, but I know this effect would look great in transparent and fluorescent acrylic as well. I can’t imagine it working as well with natural materials or microsurfaced plastic, but maybe I should experiment with that in the future!

If you have any unfocused laser tricks, or tips for keeping materials clean while processing pieces in multiple steps, let us know in the comments below! Happy holidays!