Card Holder Mechanism

I ran into this problem, where I kept breaking keycard holders. I'm not sure why I can't seem to keep one intact, but I decided to model a keycard holder because  I knew I could make a stronger one at the 3D print lab. 

 On the left you can see the first card holder I created, using Fusion 360. I used approximate dimensions from my broken card holder. On the right, you can see another similar card holder in the 3D printer slicing software, being prepared to be printed. 

I chose to print this part out of nylon using the Markforged Mark Two nylon printer in our lab. I made this choice because it seemed like my key cards were braking because they were brittle. The nylon we use is flexible enough that it cannot be shattered from normal use. Breaking it would be more like breaking a piece of rubber, so I thought it would make a good material for this project. 

Another motivation for this project was pushing the limits of the nylon printer. As you can see from the images above, this part uses a lot of thin features that are not idea for being 3D printed most of the time. The picture on the left shows the awkward placement of support material as well. I was not sure if this part would work because of the support material placement potentially making it impossible to remove, and the connection point for the key ring being only a milimeter wide. I decided to try it and see what happened, and the card holder wound up functioning well with a good tolerance for the card. I have been using it for months and it has no visible wear.