For my new Auto brake switch I would like to experience with an illuminated knob. It is only the small white strip on the front of the knob that should be illuminated. But that still requires light to go from the panel to the knob via the shaft.

So how to do that? Well “Ligth does travel through acrylic material” I thought to my self. So why not experiment with some transparent 3d-print material.

But there my knowledge fell short. Light does not travel well through 3d-print / PLA. About one centimeter. that’s it. Then the light faded out.

If I had put some additional thought in to it I could have foreseen this. Light travels easily through acrylic because it is an unbroken surface. 3d print on the other hand is layer upon layer making small unevenness that diffuses the light at each layer. And even when using transparent PLA it is not clear. So of course the light can not travel through a shaft like that.

Lesson learned: In order to have light travel from the panel through the shaft and illuminate the knob both the shaft and knob should be made from clear acrylic.

So no illuminated knobs this time.