Before ENGI 210, I had used the laser cutter once before, cutting cardboard into a stencil I then used to spray paint. Nonetheless I decided to go with a beginning level design on the laser cutter because I’ve been looking forward to making the iconic box that I’ve watched others make for years. Part of the requirements for the box is to create a raster etch of my residential college crest. Baker College means the world to me, so I decided to make my whole box a tribute to Baker, with each symbol a reference to my college’s culture.
Preparation
Because there are only two laser cutters, time spent at the machine is incredibly valuable. To help mitigate this, I prepped a file with the cut I intended to make as well as multiple test cuts that I could use to ensure the cut would work as intended. Before I could do this, though, I needed an estimate for the kerf of the laser cutter. To do this, I cut a rectangle with 14 cuts through it (including the edges), measured the distance reduction using a caliper, and divided by 14 to estimate the average kerf per cut. I found this value to be 0.018”, which I then used to generate my file.
The next day, I came back to the same machine to cut. I laid my plywood onto the bed and focused the laser using the focus tool. I then logged into the nearby computer and copied my previously generated file onto a template of the laser cutter bed. I modified the settings, which I had experimented with previously both when training to use the laser cutter and when making the kerf estimate, to match the material thickness and desired etching depth and was then ready to begin cutting.
Testing
The first thing I wanted to test was the actual cutting of the wood. I had heard that using painter’s tape helped prevent excess burning of material since the tape easily melts under the laser but keeps nearby portions covered. To first test that the laser was working correctly and to test the usage of tape in the project, I cut to 1×1” squares, one with tape and the other without. The results strongly favored the usage of tape for which the cut appeared much cleaner.
I then set my attention to experimenting with the etching. I first etched a small version of my college crest into the wood, but I noticed a decent amount of burnt material along the exterior, so I tried it again using tape, this time cutting my modified version of the Rice owl. The portions of the owl that were covered with tape looked much cleaner, but I found that the etching left many small pieces of tape that had been cut out. It would be incredibly tedious to peel off each piece, so I instead decided to experiment with the settings; I increased the laser speed, hoping to reduce some of the burnt material, but found relatively similar results. I then decided to try peeling off the painter’s tape using a layer of duct tape as a removal tool. This worked very effectively as you can see from the video. After a couple times applying the duct tape and immediately removing it, I was able to remove all the remaining painter’s tape.
The last thing I wanted to test was my kerf settings. I was very confident in my measurements, but it’s always best to test on a smaller cut before jumping into the real thing. To do this I cut out three sides of a 2×2” box, using the same settings as the 4×4” box I intended to cut. I am very glad I did because I found that my kerf settings were significantly too high. The pieces were not even close to fitting, with the finger joint being almost 1/16” too big, and suggesting a kerf overshoot of 0.027.
Since the calculated kerf overshoot was greater than my kerf settings, I reduced them to zero and repeated the cut. Now the opposite happened: The cut was about 1/64” too small! Rather than calculating a kerf adjustment, which clearly overshot the correction, I decided to do a linear interpolation between the two points and used that to determine the kerf settings that would produce a result of 0 (no overshoot or undershoot); the result I found was 0.0044”, which I modified to 0.004” to help ensure a tight fit.
The linear interpolation worked like a charm, and on the third attempt, the pieces snapped together exactly like I intended. I was astonished by how perfect the fit was because while I was expecting them to fit together, I thought I would wish for them to be a little tighter or looser—it’s so rare you get exactly the result you want! Using these settings, I re-rendered the 4×4” box cut and copied it into illustrator to prepare to make the real cut.
Cutting the Box
Before cutting, I lined the active area with painter’s tape since it worked so effectively during testing. I used weights to help eliminate the bowing of the wood which was not perfectly flat, and I began the cutting process, which took about 20 minutes for the laser cutter to complete.
I was then able to snap out each of the six sides from the plywood and remove all the tape again using the duct tape peeling method.
Assembling the Box
It was incredibly easy to assemble the box, and it produced some pretty satisfying snaps when the pieces locked into place. I made a video of the process because I found it so entertaining.
Final Assessment
Overall, I was incredibly satisfied with the finished product. Creating this box was truly a triumph of the scientific method; I came to the laser cutter prepared with a list of experiments I wanted to perform to determine how to create the box perfectly on the first attempt. There was trial and error on small test pieces as well as some good math to help me fine tune the settings. As a result, I achieved my goal of a perfect cut on the first attempt. The only flaw as far as I am concerned is a small portion of the cut that did not go all the way through, which I easily finished using an X-Acto knife. Why did the laser cutter cut everything out perfectly except for one small portion? I am not sure, but the result was slight cosmetic damage to the exterior, where you can tell a cut was finished by hand and not with the laser.
Below is an image of each side of the box, including my name and class information, my college crest, a can of shaving cream, “Baker College” in the classic Old English font, Sammy the owl with devil horns, and a Christmas tree!
Cost
Plywood (estimated from Lowe’s and HomeDepot online stores): $8
Equipment: $0 (Shared resource)
Labor ($15/hr for 2.5 hrs): $37.50
Total Cost: $45.50
