This week, our assignment was to create a press-fit box using the laser cutter.

Procedure:

We started off by using makeabox.io to create the 3D model for the box. The settings that we chose are listed below.

We set the internal dimensions as 3.8 inches as the thickness of the plywood is 0.2 inches (measured with a digital caliper). Together, this would make a box of 4 inches on all sides. The tabs that would fit together to make the box were set to have a thickness of 0.5 inches.

We were planning on determining the appropriate kerf for the box to fit together appropriately. Because many students were having trouble with this, it was suggested that we get recommendations from those who had already done the kerf calculation. We were told that a kerf between around 0.006 and 0.009 would be best, so we chose to use 0.008.

For the laser cutter, we set where we wanted our images to be cut, the stroke size (0.072), the bed dimensions, the speed (5%), power (100%), and frequency (10f).

We did a practice cut using the top two sides of the box to see how the fit was (and so we could use the pieces if they did fit together well). Before cutting, we covered the necessary area with tape to prevent burning at the edges. Once we saw that our settings were correct, we also decided to test the images that we would be etching onto the surface. Because we had set the origin and the board in the corner of the bed, we were able to put the cutouts back in the original wood so that the images would line up. One thing we learned during this process was that we needed to delete the lines of the side outlines so that they are not etched into the surface. (We could have alternatively done both the cutting and etching steps at once on the laser cutter, but we opted for the other procedure so that if the etching process had problems, the whole print would not be messed up.

We finalized our images and text and made the two files that we would be using to cut the box. We then taped the board and started the print.

Once the pieces were cut, we put them together and the fit was very tight.

Cost  Analysis:

Raw material cost  

Material	Ticket Price	Spent
Plywood	$29.88 (4×8 feet)	$5.60 (2×3 feet)
Masking Tape	$22.49 (60 yards)	$1.50 (4 yards)
Total		$7.10

Labor cost

Assuming minimum wage in Texas of $7.25:

Task	Time	Spent
Training	1 hour	$7.25
Cutting and assembling	2.5 hours	$18.13
Total		$25.38

Machine time/machine hour cost

Machine hour cost can be calculated by dividing the cost of the machine by the total hours it should function, and multiplying that result by the time that the machine was in use.

The EPILOG Fusion laser cutter at the OEDK costs an average of $32,500, and is expected to last for somewhere around fifteen years. For the case of fifteen years of use, and since I used the laser cutter for 2.5 hours, the total machine time cost was $0.62.

$32,500/(131,490 hours) = ($0.247/hour)×2.5hours = $0.618

Project total: $33.10

Overall, I really enjoyed this project and hope to use the laser cutter for more projects in the future!