The third assignment for this class was to make a press-fit wooden box using the laser cutter.

First, I went to makercase to create my box and generate an SVG file that would allow it to be cut. My box was configured according to the dimensions seen below. I found the thickness of my wood to be 0.22″ using a pair of calipers, and I chose a finger size of 0.5225″ to achieve a nice 7 interlocking fingers on each edge.

 

Next, I had to set the kerf. The assignment recommended a kerf setting between 0.012” to 0.015”, but I heard from other students that this resulted in too tight of a fit. Because one of the laser cutters was down, many students were trying to use it at the same time. So, instead of using valuable machine time to iteratively test the fit using different kerf settings, I consulted blog posts from the previous year. I decided on a kerf of 0.006″, and as we will see later, this ended up being perfect.

 

Once I had the SVG file for my cuts, it was time to add designs to engrave. For the text, I chose to use a stencil-like font to match the burnt wood aesthetic. I put the Rice University logo on the back and added the logo of each of Houston’s four major sports teams to the remaining faces. For some of these logos, I performed manual thresholding in photoshop to achieve a clean binary image.

 

It was now time to cut! When I went to print on the laser cutter, however, I was having an issue where it would not differentiate my lines to be cut from my engravings. I used red 0.001″ hairlines and tried color thresholding as well, but had no luck. I solved this issue by making it a two-step process where I would first engrave, and then cut. I made a copy of the file without the box outlines and printed it. I made sure to record the x and y coordinates of this print so that The cuts would overlay on the engravings perfectly.

 

Once the engraving was finished, I made a copy of the original file with just the lines to cut. I used a frequency of 10%, power of 100%, and speed of 15% for my cuts. The engravings were perfectly centered within the cuts, which was great to see.

 

After the cutting was finished, it was time to assemble. After removing my wood, however, I found that the cut had not gone 100% through in a couple areas. So, I took an X-acto knife and carefully cut through the thin areas of wood that were still connected. This was not a difficult process, but the results can be seen on a few of the fingers where a raw wood color is shown rather than a full char from the laser. Anyway, after all of the pieces were free, I pressed them together. I achieved a very snug and sturdy fit, which I was happy with. I used a rubber mallet to ensure all pieces were slotted tightly and constructed the box without any problems.

 

The total cost of this laser-cut box, including the cost of all wood, labor, and machine time involved, was $89.83.