Marble Run Elevator for Gravitrax

This model is a marble elevator compatible with Gravitrax marble run sets. You can see it in action here:

https://www.youtube.com/watch?v=r8R_3OTaM9g

Each elevator has three independent inputs with corresponding outputs on the respective opposite side. The motor is integrated in the base of the elevator to ensure a low center of mass with more stability, even at high rotation speeds.

I designed this elevator after downloading and printing an elevator I found on one of the 3d print sites, which was really disappointing. It had the motor at the top and became very unstable, very quickly. So my son had not much fun with that. Developing my own design then turned out to be much more complex and time consuming than I had initially envisioned. But it was worth it, as it just works as intended and needs no intervention or help from my side, when my children use it.

The power is delivered via a USB cable from a power station. The power station is designed to house a 9V battery and a some electronics to vary the output voltage, which varies the elevator speeds.

IMPORTANT: Do not connect anything else to the power station but the elevators. However, the elevators can also be powered by a standard USB type charger, if you do not want to build the power station.

Have a look at the images to see how everything fits together. The additional parts you need are the following:

The separate parts are designed with holes for threaded inserts, so that eveything can be connected tightly with screws. You will need inserts M2x4x3.2 mm and screws 2x M2x5mm and 4x M2x12mm. I used this set from Amazon:

https://www.amazon.de/Gewindeeinsatz-Einpressmutter-Gewindebuchsen-Kunststoff-Box-Kunststoffteiledurch/dp/B09B7F2XM3

You also need one ball bearing as used in skateboards or inline skates. The ball bearing must have an inner diameter of 8mm and outer diameter of 22mm and a thickness of 7mm. I used a 608ZZ ball bearing.

As motor you need one with a gearbox that does 1000rpm at 12V of this make:

https://www.amazon.de/gp/product/B08599WJHH

There are a couple of variants you can choose from, so make sure you pick the right one. If you buy these motors directly from China they are much cheaper.

The model is designed to house these types of USB-C sockets:

https://www.amazon.de/gp/product/B09YLVSPQX/

You need to solder them before inserting them into the elevator compartment from below, as the support that holds them in place in the print, breaks easily when you try to push them back out.

The USB-A sockets for the power supply I used, were these:

https://www.amazon.de/gp/product/B07VBRTDVF

To control the motor speed I used this bit of electronics:

https://www.amazon.de/gp/product/B09Q8BQ1KK/

And you need a 9V battery connector like these ones:

https://www.amazon.de/SENZEAL-Batterie-Schnappverbinder-Elektrische-Spielzeug/dp/B07MW18YPD

I printed everything with a 0.3mm layer height. You will of course get much nicer surfaces with lower layer heights. Some parts have supports included in the design. The only part where you need to add supports is the top of the power station. The marble path won't print properly without some support at the ends.