Casting silicone rubber
In a 3D printed mold
I drive a classic car, an Austin A30 to be exact. However because these cars are 60+ years old they require maintenance. Most parts are readily available, although the rubber parts and some panels for these cars can be tricky to obtain. Thankfully owners clubs and parts vendors sometimes spend the cash to have a mold created. I wanted to try making silicone parts from an 3D printed mold. However I did not want to make just any part. As I said, most parts are available so my criteria where; hidden part (this ensures that even if my parts aren't perfect, they would be usable), the change in material would nog affect the performance of the part. In the end two candidates remained. The blanking grommet for the heater and the handbrake cover that lives underneath the car. I decided to start with the blanking grommet. The video shows all the steps and for reference the steps are also explained along with pictures below.
This is the original part taken from my car. A second one was also lend to me. In the end I based my design on the second one.
As you can see, the part is not in great condition. The rubber deteriorates after that many years.
I started out modeling the part and housing that would produce the actual mold.
Doing it this way allowed me to use spray filler and sanding to get rid of the print lines.
The mold was printed and prepped for casting the mold.
This took more silicone than I anticipated. I used a "mini caulking gun" (meant for cookie dough) however this was not capable of injecting with enough pressure. So I abandoned this idea in favor of using a medical syringe.
Cutting into the transparent silicone mold with a X-acto knife was very easy. However, next time I would opt for creating one half first with modeling clay and then the second with locating indentations.
Drilling out the injection hole was necessary to create a decent seal around the mouth of the syringe.
The finished part looks a lot like the model. :-D
I am very happy with the result, but there is still room for improvement. Always Learning!