January, 2024
I found a cool Door Light with a Star Wars Imperial Logo that matched well with the Star Wars-theme I have going with my black-and-white (i.e. “Stormtrooper color”) Jeep Wrangler. I previously got a Star Wars Imperial Logo spare tire cover, a vanity plate and other trip accessories. My thought was that this would be an inexpensive an fun add-on.
THE PROBLEM: where to mount it?
Unlike most car doors, the Jeep Wrangler has these stretchy cargo nets that allow you to hold things. While this is often convenient, it leaves no room to properly mount the light – something I wish I had thought of before buying the door light!
My goal was to avoid drilling any new holes, but to have a mounting service that was very rigid and flat. Additionally, it had to be low enough to enter the magnetic field of the stationary magnet that is mounted to the inside floor board to shut off the light while the door is closed. Finally, I wanted to retain full use of the cargo net.
THE SOLUTION: 3D print a special bracket that allows me to mount the door light.
Upon careful inspection, I found that there was an existing screw holding the door trim on. My idea was to make use of this screw as the primary mounting point for the bracket. It was far enough out on the door that it would allow for good projection of the light when the door opens (too close to the hinge and the light is blocked by the car and the effect is lost).
I did some rapid prototyping and came up with a strange-looking design that exactly fit the unique contour of the screw hole and door frame. I used Tinkercad to create the designs and printed them on my 3D printer using PLA. I iterated the design until I got the desired fit and location on the door.
There was an interesting trapezoidal shape where the screw goes that I had to match to get the benefit of the tight tolerance to keep the piece stable. There was a small drop from the plastic trim the metal door, and then a step down to an angled door frame. It took a while to get all these contours correct, but it was worth it.
After the design was done, I added some holes in the side of the piece which allowed me to:
- Reduce the amount of plastic used
- Reduce the print time
- Reduce the weight of the final design
- Add strength by providing re-enforcement around the holes.
I printed with 4 perimeters and 30% grid infill for high strength and durability (hopefully). Print time was about 3 hours. I printed it with the flat face-down which required the use of supports for the trapezoidal screw hole.
It looks strange, but none of this will be seen since its all covered by the door light. My initial plan was to build a strap or bracket that wrapped around the front of the door light to secure it in place. However, I later changed direction and decided to just use adhesive on the back of the door light to secure it to the bracket, as intended by the manufacturer. This allowed easy access to the on/off button, and the battery door for battery changes (3 AAA) that would have been blocked by the front-strap.
In order to ensure the most secure bond, I ignored the cheap double-sided adhesive pad that came with the product and opted to use some industrial 3M double-sided foam-tape. This is expensive, but worth every penny as it has crazy strong grip and lasts a long time. I cut small strips of this and applied it to the front plate. I used pressure to ensure good adhesion. The main down-side of this tape is that the top layer is difficult to peel off. I had to use a razor blade to free a corner to pull.
In addition to the single screw mount, I added some double sided adhesive tape to the bottom inside of the piece to adhere to the door metal. This turned out to be a really good call as it made the piece very rigid when mounted.
After mounting the piece and re-inserting the screw, I peeled the top layer tape and press-fit the lamp light module. I tested by slamming the door closed multiple times to confirm nothing was moving when the door closed.
Next, I opted to throw away the crappy small magnet that comes with the product and opted for a larger magnet with a mounting hole in the middle. My magnet has a larger magnetic field and allowed more room between the door light and the magnet while still triggering the light off. Using trial-and-error, I determined the correct location to mount the magnet and marked them. I found I had to place the magnet in a different location on the passenger and driver side because of the orientation of the lamp and magnetic sensor on the door light.
Untrusting of adhesive for this high-traffic location, I opted to use 2-part Epoxy re-enforced with a screw + washer through the middle into the plastic trim of the floor (yes, I broke my rule and drilled a hole). I sanded the surface and cleaned with alcohol before applying the glue, hoping for optimum adhesion.
Conclusions:
Overall, the project took about 8 hours to rapid prototype, and then about 2 hours for the final install. Zero out-of-pocket cost as I had all the material I needed on-hand.
Considering the low price of this product, I’m impressed with it. It’s bright and easily visible, even in direct sunlight. It is a great addition to the theme of the vehicle and will hopefully be a great conversation piece in the future. It automatically shuts on and off to conserve battery power and the install was generally uneventful once the small matter of mounting was addressed. Time will tell how often the batteries need to be changed, but with the auto-off feature, I expect they will last months.
One concern I have is the use of PLA for printing the bracket. This will likely require a replacement as PLA is known to not handle very hot conditions well (it melts) and this car will most certainly experience very hot (100+ degrees F) conditions when parked outside in the summer. Next, PLA (as with most plastics) will get brittle over time and crack when exposed to cold weather and this car will most certainly be exposed to sub-freezing conditions when parked outside in the winter. The good news is that I have archived the design and can easily re-print if needed (perhaps PLA+ or ABS or something more rigid next time).
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