This is one of the first things I experimented with after getting my laser cutter. I wanted to see what could be done with the cutter besides marking and vector cutting, so I decided to experiment with etching channels in acrylic. This is a simple, mechanical "inverter" is the by-product of this and a recent discussion I had with a coworker about physical representations of logic gates.

On the "input" side, the plunger being pushed in represents a 1 on the input, and pulled out represents a zero. On the output, a pulled in plunger represents a 0, and pushed out a 1. This convention is used because the output is presumably being used as the input of the next gate in the chain.

The basic question I wanted to know was “How well can the laser cutter selectively vaporize material?” If the answer to that question was “very well” then it opens up a few new possibilities for laser cut parts, at least for those with direct access to a laser cutter. Basically, this would allow you to cut channels of various depths as well as mark and cut with the laser. This project was simply a test to see if it was feasible to etch parts.

The parts for the mechanical inverter where cut from 1/8” acrylic and the sections that were etched away were done in two passes with the following settings on my 35W Epilog (raster only): 10% Speed 60% Power 600 DPI (If you’re wondering how I chose those settings, I have a raster test pattern that I use to determine the power/speed settings for a given material)

I made sure with a pair of digital calipers that the channels were etched more than half way through the acrylic after two passes. The pieces were then cut using the standard settings for vector cutting 1/8” acrylic. After assembly, I taped the two halves of the assembly together so I could disassemble it later.

Overall, I’d say it worked reasonably well. This process is pretty time consuming though, so I don’t recommend trying it on anything too large. I’ve used it to add various small features to some of my other projects, including a lip for a CR2025 battery holder cut from 1/8” acrylic.

Two things I noticed with this process:

1. The powdered plastic residue that is normally associated with etching plastic will deposit in the channels you cut. You may want to blow off the piece you’re etching with some compressed air in between passes to keep this residue from building up and interfering with the cut depth (it also seems to re-fuse with the underlying material on subsequent passes).
2. Don’t overheat the acrylic you’re etching by trying to take too much material off at a time, this will cause the acrylic to warp. This can be especially problematic if you etch a large area.

Questions and comments welcome.