Laser Tips 2: Laser-Cut Paper Halloween Masks

As with my last instructable, Laser Tips 1: Engraved Geocaching FTF Coins, the goal of this instructable isn't to explain the project design itself, but more to explain a general technique that comes in handy:

Laying out and cutting a bunch of items from paper (or cardstock) at once.

The City of Auburn has an annual Trunk or Treat Harvest Festival in the park by the makerspace, and this year our workhorse, the Epilog Helix 50 watt laser, is helping out by pre-cutting some crafts for the kiddos without the fine motor skills (or too sugar-hyper) to cut the detailed paper shapes themselves.

Paper is, in my opinion, a vastly underutilized material for laser cutting. It's cheap, colorful, versatile, formable into 3d shapes, and is just great, really. But there are a few simple considerations to note when laser-cutting with paper, as well as when mass-producing items of any kind!

So let's get into it!

Step 1: A Note on Design...

Since I was only making these as an example, rather than create an original design I traced an image from Ye Olde Google. SO I will not be providing my vector files! But I will include the original graphic I drew this from, so you can check out their etsy page.

The screencap has the tool highlighted that I used in CorelDraw; I've gotten pretty enthusiastic lately about the B-spline tool when it comes to creating outlines from bitmaps.

YES I am aware of bitmap trace; however I've found that a black outline from these coloring-book style graphics (vs a black silhouette) makes a very messy vector line on the in and outside of the black line, which requires so much editing and fiddling that I could have traced it cleanly from the start. So I did that instead.

Step 2: Layout

Now that you have your file, it's time to pay attention to layout and nesting!

Considerations:

-size of your paper (8.5x11", seen here; AKA standard 'letter size' in America)

-size of your file (because these are masks, the size is not super flexible; if you're making smaller objects or objects that can be sized up or down, you can fiddle with this to get more out of each sheet of paper)

-size of your cutting bed (mine is 24x18")

My first step was to change my document size to the size of my paper, so it was easy for me to figure out how to lay out my final shapes, after having sized them up to the final size I wanted. I tried a couple different rotations and nestings, but couldn't get more than a couple to the sheet, so I gave them a good amount of space. Since you'll be clamping the paper down (see later steps), make sure you have some wiggle room, ideally .5" on all edges, to allow for paper scooch.

Then, I resized my document to the size of my laser cutter bed. The best layout I've found from my experience is the one shown in the pics, with 4 sheets. You can theoretically get more sheets on a bed this size, but in my experience it's more trouble than it's worth, and registering the drawings to the sheets on the cutting bed is not super reliable. So, I drew 4 identical 8.5x11" rectangles and arranged them to mimic this arrangement, to make it easy to arrange my drawings in the center of these rectangles.

IMPORTANT: note the difference in line thickness labeled in the pics; the Epilog is designed to only vector cut lines labeled as "hairline" thickness, and anything thicker will register as a raster file. The line thickness of the masks is hairline, and the rectangles are .5 pt. This is important in the next step.

Step 3: Laser Settings

What I usually do to maximize the gain from my investment in set-up time with these files it cut 2-page stacks, 4 at a time, meaning that each cut will produce, in this case, 16 masks.

I ran a few tests, on both regular-weight colored paper and cardstock. See pics for details.

In the Epilog printer settings, I checked 'vector only' to cut. Therefore, my rectangles in my layout will be excluded from the cut.

Step 4: Laying Out the Material

It's very important when doing multiple stacks of paper to clamp down the edges, because the air-assist in the laser can disrupt the positioning of the sheets otherwise, leading to a full or partial failure of your cut. The Epilog's rulers are built-in clamps. It's not necessary in my experience to have more than one edge clamped. This is the reason, when laying out your file, you leave a good-sized border. If your laser doesn't have built-in clamps, you can approximate the effect with a long steel ruler or straight-edge laid out on the edge, maybe with some additional weights added from magnets or such.

For the lower stacks, don't line up the bottom edge of the paper with the bottom edge of the cutting bed; instead, line up the bottom edge of the paper with the 18" mark, which is the ACTUAL maximum cutting border. Since the right-hand clamp doesn't have ruler markings, I use my bottom-left paper stack to visually line up the bottom-right edge with the 18" mark as well.

Note in the final pic the similarity with the digital layout in the previous step.

Also note, I've tried before to push my luck with stacks of 3 or 4 pages. It doesn't work well. Paper is very flammable and carries more of a risk in the laser than most materials, especially as fine detailed parts start to curl up or get blown loose. To cut through a stack of more than 2 pages, you have to raise the power to a degree that I consider unsafe, from my experience, for the upper-most layer, and also the visual results are less optimal (more smoke staining on all layers).

Step 5: Finale!

So, in my initial tests, a page with 2 masks took 43 seconds to cut. Cutting 16 masks with this method took 2 min 29 sec. For comparison, that's about 21 sec/ea vs 9 sec/ea. When you need to make 200 of something, that's the difference between 1 hr and 10 min, and 30 min (*cool shades emoji*).

At these settings the masks just pull out of the paper. One thing with working with paper, since it doesn't (and shouldn't for safety reasons!) smolder like wood does, there will ALWAYS be sticking points, kind of a micro-perforation that should tear easily. This happens most around tight curves, where the laser is moving most across both axes.

Put a ribbon or pipe cleaner or piece of elastic through the holes and you're ready for Halloweeeeeeeeen!