For this assignment, we’ve been tasked with using the laser cutter to create a box with press-fit joints, engraved with our name and residential college. The box must be tightly fitted with minimum dimensions of 4’’ x 4’’x 4’’. Through a good amount of testing and iteration, I created a box that fulfills these requirements.
The first step was to print the kerf test to measure the average kerf to account for in our design. When I completed this test, I measured a gap of 0.2 inches, indicating a 0.02 inch kerf. I started by printing two sides of a 3’’ box. These sides didn’t fit together, indicating my kerf value was too high. I conducted the same test with kerf values of 0.018 and 0.015 inches, but both values were still too high. I finally dropped to a kerf of 0.01 inches, which seemed to be a good fit.
I used consistent settings for cutting and engraving throughout this process. For cutting, I used 6 speed, 100 power, 10 frequency. For engraving I used 50 speed, 25 power. These values were chosen based on material type, thickness, and desired engraving aesthetic.
In preparation for the final box, I experimented with using masking tape to protect the wood from woodburn. The tape produced a much cleaner look for the sides of the box. However, at some points the laser didn’t cut completely through the wood, engraving through the masking tape was inconsistent, and the wood splintered in some places when I removed the tape. As a result, I decided against using masking tape for the final box.
In preparation for the final cut, I input parameters describing material thickness (0.2 inches), kerf (0.01 inches), and finger width (0.6 inches). When I printed a full-size box with a kerf value of 0.01 inches, I was surprised to find that the box was far too loose; I could remove any side of it with very little effort. So I returned to testing, slowly increasing the kerf value until I reached 0.012 inches. I printed the final box with this kerf value, and it made for a very tight fit. To fully assemble the box, I had to hammer in the sides until the box was firmly held together.
Cost Estimate:
My process:
- 1 sheet of plywood ~ 1/8x2x4’’: $15
- Operating cost: 2 hr * $12.73/hr = $25.46
- This estimate comes from Alpha Lazer’s estimate for the operating cost of a 4kW CO2 laser cutter
- Labor cost: 3 hr * $16.56/hr = $49.68
- This estimate comes from the average hourly pay for a maker space job according to ZipRecruiter
- Total: $90.14
A more efficient process:
- ½ sheet of plywood: $7.50
- Operating cost: ½ hour * $12.73/hr = $6.37
- Labor cost: ½ hour * $16.56 = $8.28
- Total: $22.15
