The Redesign

I wanted to keep my design simple to create while also remaining accessible. I added a curve to the bottom (shown as top) so it would be easy to put the FasTrak into the holder while the little nub on the right side would prevent the FasTrak from sliding out.

I also added side barriers that would keep the FasTrak in place preventing it from sliding out of the sides. This barrier is a perfect fit for the FasTrak Flex as it follows the radius of the device.

Along with these changes, I resigned the clip portion of the holder (bottom), instead of having the clip rely on pure stiffness from the first design, the new design relies on flexibility. This helps the holder stay on the visor without sliding off easily.

This design is super easy to use especially with the addition of the triangular indent and circular indent on the left side that provide a designated spot for flexibility.

Current Progress (08/27/25)

As of August 25, 2025; the FasTrak holder works as intended, it slides onto the visor in my vehicle and is easy to use. I am able to remove it when needed and easily place it back.

Unfortunately Polyastic Acid (PLA) is not great in warmer temperatures, so after about 1 day with 75 degree temperatures (close to 90 degrees in the vehicle) the plastic started to warp and deform due to the heat and pressure it has to withstand.

I am in the process of using a different material; HT-PLA-GF Filament by Polymaker. While this filament does require a new nozzle for my 3D Printer, it provides the reliability of being able to withstand higher temperatures and pressures do the the added glass fiber and recommend

The Annealing

I chose two different annealing processes for this project: Open Air Annealing and Fine-Salt Annealing.

Open Air Annealing consists of simply adding parts into an oven at 100 degrees celsius for 30 minutes. The main issues with this are that the parts are prone to warping and drooping if handled and placed incorrectly.

Fine-Salt Annealing uses a process similar to casting; the printed parts are to be placed into fine salt and fully surrounded. Then the parts and salt are set in an oven at 100 degrees celsius for 30-90 minutes depending on the amount of salt used and size of part.

I found that the results of both processes were quite similar, the only issue was the open-air annealed parts did warp and have inconsistencies.

This current design used these settings:
55% Infill Density
Gyroid Infill Pattern
2 Wall Loops
Ironed Top Layer
0.5mm Line Widths All-Around
0.25mm Layer Height

Annealed Results

The annealed parts have not been strengthened thus far. I have experienced a separation between the infill and walls of the prints as the prints are stressed to their expected levels.

At the start of the stress testing, the front of the print (bottom as shown) started separation and cracking. This was not good as this project would have to withstand the stress of being separated and bent multiple times.

Active Stress Testing

After continuous stress testing, the results were not getting any better. As shown in the picture, active bending would further separate the walls from the infill. This is a major issue as it severely weakens the structure of the print.

As I continued to pull apart the print for stress testing, rather than slightly deforming or stretching the material snapped.

This is not good because it can cause serious injuries if the item is in the hands of a child. If you haven’t worked with PLA before; when a print snaps, sharp edges are created and it can and will cause serious injuries during the snap and in the aftermath.

I want this project to be safe and reliable, and these issues are the complete opposite of what is happening.

The Second Annealing

As annealing in Fine-Salt and Open-Air was unsuccessful I sought advice on forums and was recommended to try boiling the parts at 100 Celsius for ~30 minutes.

I printed two different versions of this holder, one had a 50% infill similarly to previous prints and a new print with a 90% infill. I hoped that with more material within the print the annealing process would further strengthen the print as it would have more material to crystalize and strengthen.

Along with an increase of infill, I have also increased the amount of walls from 2 to 3. This would significantly increase the strength and help it bend back to its original position.

50% Infill Water Annealing

Initially the 50% Infill piece felt stronger compared to the Salt/Open-Air Annealing. Upon applying stress it was less prone to snapping. Unfortunately it still suffered separation between the walls and infill.

This is not good because this specific area needs to be able to withstand a high amount of constant stress and if it fails it could cause serious issues such as plastic falling off while driving and the whole bottom portion of the holder dropping down.

Another issue is the bend-zone I created, it would snap when trying to connect all parts together. I do not believe this would be an issue during average use as its not an intended movement that would ever be done. Since I don’t believe this would be an important issue, I will not prioritize resolving it at this time.

90% Infill Water Annealing

The 90% Infill piece was significantly heavier and sturdier. Active bending was harder and took more effort than the 50% infill.

As stress was applied, the part did not snap like the 50% infill did, it was able to withstand more stress without failure. This is the strongest iteration thus far and I believe it may be the infill I will use in the future. I will test lower amount of infill ranging from 55% to 85% to find the piece with the most strength.

New Updated Design

As I went through the process of testing the previous design, I met with my professor Luis Cabrales and got advice that I should try using something like metal for the part that connects to the visor. This was recommended because metal has more memory and is not affected by temperature as much as plastic is. I thought this was a good idea I updated my design to be more efficient and contain a singular visor mounting area.