3D marble run

by Thomas 

A three-dimensional ball track? That sounds really cool. Thomas has created such a model and put a lot of creativity into it. We say wow, and are happy that Thomas presents his model here.

"It's a three-dimensional marble run - three dimensions, because it's three intertwined angular planes. Once all the balls have reached the end of a track, the model continues to rotate by exactly 120°. The balls tilt to the next angular plane and then run into a mechanism for separating the balls. This mechanism is designed in different ways for all three tracks and each of the three tracks is independent. One lane even has a loop, in another lane there is a sound tube.

The control system is, as usual for me, classically constructed from silver pieces and single ICs. Basically it is a simple time control, which takes the course of the balls in the tracks "generously" into account, then turns the construction further by 120° and leads the balls over the separate separating stop bit by bit into the active track. The precise stop after exactly 120° is achieved on the one hand by means of a heavy locking bolt in the base, and on the other hand by a button as self-timer to switch off the main motor. The main motor drives the model via a specially designed ring consisting of 48 blocks 15 and 48 angle blocks 7.5° and on top of that a mono-motor.
213 chain links are attached to the chain (to be seen on the reverse side).
The rotating part weighs about 7.5 kg (!) in total and is finely balanced in terms of mass. The necessary driving force is so minimal that a small finger push is sufficient. A further factor for the smooth running is undoubtedly the metal tube installed in the middle and mounted on rollers in the supports. The only imbalance is in fact the eight balls themselves, which lie in the track.
As far as the parts as a whole are concerned, I stopped counting 120 with 120 angle brackets installed; also because in the different construction phases, there were always modifications necessary. After all, a construction like this demands, all masses must be concentrated evenly into the middle, no matter at which position the turning part just is - there is no upside or downside. How many angle-stones I did use, also at the moment is not to say exactly. Much used material anyway will function only by massive stabilizations and now would not be accessible from outside. However, five motors are safely installed - four mini motors and one large XM motor.
By the way: The power supply for the moving part is located in the base. This is realized with standard M4 screws and matching M4 cap nuts - of course, also precisely aligned. Thus, on the one hand, always the correct motor (i.e. always "on top") for the separation of the balls and on the other hand, a ring circuit consisting of six Rainbow-LEDs is supplied.
For the transport of the model, the stand can be disassembled into two parts in a few easy steps, the rotating part on the metal tube can be lifted out and placed on a specially designed stand".