Laser Etching acrylic can be a wonderful experience, especially if you're never worked with acrylic before and have hangups against it as a material. I fall into that category, someone who has detested all things plastic-y since childhood. But I have to admit, its such a wonderful material to work with for etching and shaping, since it forms easily and a bandsaw cuts through it like butter.
In this tutorial I'll show you how to make clear, crisp etches using acrylic in any laser etching machine.
Step 1: Etching Puts Stress on Your Materials
There is simply no way around it- etching stresses materials.
For this project I want a specific depth in my etches, and so I've chosen to push the settings as far as I can safely go without burning or scorching the acrylic. I've tried skipping around to reduce heat build-up on my acrylic, I've tried long breaks with the laser off, setting the laser to etch less over more passes. Nothing works like setting it to 600 DPI with 70% speed and 80% power.
I decided to make some fixtures, which I'll call jigs in this tutorial so I can have a catchy Instructables title. These fixtures will hold my acrylic in place so the edges can't curl up while etching.
To make these jigs you need the following materials: (McMaster Carr to get Lucky)
Metric Zinc-plated Class 5 Steel Wing Nuts, M4 screw size, 0.7 MM pitch
Metric 316 stainless steel Pan Head Phillips Machine Screws, M4 size, 20 mm length, 0.7 mm pitch
Metric Extra-thick Black Oxide Steel Flat Washer, M4 screw size, 14 mm OD, 2.5-3,4 mm thick
Metric Type 316 Stainless Steel Large-diameter flat washer, m4 screw size, 12 mm OD, 9mm-1.1 mm thick
1/4 inch thick clear acrylic, (I used Evonik brand but you can use any material that won't offgas chlorine when heated, including plywood. The clear lets you see what your material better/)
3/8 inch thick plywood
Step 2: Design Your Jigs
I designed these jigs in Illustrator. Basically, you're designing two plates that screw together and sandwich the acrylic between, simple as that. I rounded my corners and made sure to space the holes so there is enough space to get a good clamp on your acrylic. I feel pretty clever because I nested my cuts to save time and materials, and I recommend you do it too, since it feels good and looks professional.
The screw holes have to be large enough to fit the screws but not so big that the screws fall out when you're assembling the whole sandwich. I made my screw holes 4 mm in diameter to fit the size screws I have listed in the materials. Be sure to size your holes accordingly if you're changing up the screws. I found that the sizes here are strong enough and give me the space I need to make a good hole while still holding the material tight, so I recommend sticking with this.
You can make your own or use the Illustrator file I've attached here.
Step 3: Cut Your Files and Assemble
Cut the files in a laser cutter. Remember to cut the two halves of the sandwich, the clear acrylic having an inner cutout and the plywood having no cutout, since its the bottom plate.
Then assemble using the wingnuts and whatever thickness washer you need to sandwich your acrylic in tightly without over-tightening or having to screw the wingnut down too far.
Check the clearance of the laser with a dry run, finger on the stop bottun, to assure your laser doesn't hit the wingnuts and cause damage.
Simple as that- no warping while in the jigs! Keep in mind that the acrylic will still warp, and when you release it from the sandwich it will flex up. Heat treat it again in the other side with a hairdryer or heatgun to completely flatten. I've been etching both sides and I find it completely flattens out when I send it through on the other side.
See the next step for a few other tricks I've learned.
Step 4: Getting That Darned Plastic Coating Off the Etch
I like to leave the plastic coating in the acrylic while etching since it keeps the edge crisp and clear. It takes forever to it off in the etching makes a tight pattern such as mine is. I tried air to blow off the coating, but finally settled on power washer.
If you have access to a power washer, I highly recommend using it to get that darn coating off easily.
Step 5: Admire Your Work
When you have spend time standing next to the laser etcher like I have, its great to stand back and admire your hard work for a second.
Thanks for reading!