Objective
For week two, we are focusing on computer controlled cutting. Specifically, I will be using the laser cutter on cardboart to create a “Parametric Construction Kit” in which the parts can be combined multiple ways. This will be a strong test of parametric design skills introduced last week, and will require a strong understanding of the machine and materials used.
Group Assignment
We were oriented to the laser cutter in groups. Diana, the architecture section’s amazing section lead, started with the the basics (turning on the laser cutter, how to use rhino or other CAD software to interface with the laser cutter, troubleshooting when the laser cutter isn’t responding, etc) before taking us through the factors that would make our laser cutting more or less successful. She demonstrated how the width of cardboard often isn’t consistent all the way through a sheet, and how the curvature of the cardboard will change the focal distance of the laser and then affect the cut.
Aside from the material, we also examined how speed, power, and frequency affect cuts. In general, Diana recommended solely adjusting the power, so we tried cutting a random shape with power ranging from 18 all the way up to 45 (we decided not to go higher than 45 as we started having fire scares at that point).Below, you can see the results of using 30 speed with 18 power, 23 power, 30 power, 36 power, 39 power, and 45 power (L to R).
There we also have some photos of a couple of the back after a few cuts. The first is at 30 power, which you can see was a little short of cutting all the way through. The second is at 45 power; the shape popped right out!
Individual Assignment
For my individual assignment, I decided to build a sort of linkoln log set using cardboard. This is for two reasons:
- I always wanted lincoln logs as a kid but never had any
- My nephew is extremely interested in becoming an architect, so it seemed like it could be a fun gift for him
I started by deciding which pieces I would need and sketching them out. To keep it simple, I settled on long logs, short logs, and a gable. I realized that since the logs would be flat, they could double as roof slats, so these three types of pieces should be enough to build some house variations.
Next, I identified the parameters I would need. My initial list was:
- Log height
- Long log length
- Short log length
- Joint width
- Joint height
- Joint offset (distance from the edge)
- Distance between joints
- Laser diameter (kerf)
Once I had the pieces drawn out, it was time for laser cutting. Here, I encountered a few challenges. First, in the architecture lab we can only print to the laser cutters using Rhino. Since I made my designs in Fusion 360, I needed to convert my design to a .dwg file. This wasn’t a big deal until I realized that I’d made a major measuring error in the spacing for roof slats on my gables. Because all my parameters were in Fusion, it was quicker to just pull out my laptop, edit the file in fusion, and then send it back over…except I realized my parameters were somewhat broken.
In the end I re-drew the gable from scratch because it was easier than trying to fix the old parameters. While I was doing this I also widened the joints and increased the chamfer size on all pieces because my test cuts were more difficult to connect than I expected.
The next obstacle, which I somewhat anticipated, was that the cardboard sheet I was using was heavily curved, resulting in different focal distances throughout. I needed to cancel a couple jobs to adjust, but pretty soon was able to get clean cuts in most areas of the cardboard. At the top, where the cardboard was flattest, I used 45 power and 30 speed. In the middle, I needed to lower the cardboard in the laser cutter and increased power and speed to 50 and 35 respectively.
The biggest problem area was at the bottom of the sheet. Regardless of increasing power and speed or adjusting the focal distance, I still kept getting wide lines that failed to cut all the way through. What’s more, I couldn’t easily see where the laser was cutting, so I lived in constant paranoia of a potential fire.
Eventually I flipped the cardboard around and moved the bottom to the top of the machine and…this fixed everything. I don’t know if this caused the cardboard to sit flatter or if there’s just something finicky with cutting at the bottom of the laser cutter, but once I flipped things the rest went smoothly. No fires, no more issues, just lots of logs.
Results
In the end the Lincoln logs were a success! I think I was overly generous with the kerf width, which resulted in tight tolerances for the joints, but they’re still pretty easy to attach and detach. The real test will be giving these to my nephew and getting his review – if he abandons his architecture dream then I think I’ll be to blame, so the stakes are high.
Takeaways
- Double check all parameters as you go. I don’t know where some of them got broken, and it would have been much easier to trouble shoot as I went rather than to try to find what might be multiple issues later on.
- Measure twice, cut once. My dad’s voice played on repeat in my head as I frantically fixed my gables…
- Get more wild with it. I’m very proud of my Lincoln logs, but looking back it would have been fun to incorporate some curved parts or even simply use a lower powered laser for some design etching on the different pieces.
File Link:
© 2024 Nathan Keene Wiegand