This is a marble run with three flippers which tip either left or right every time a marble goes through
The pivots of the flippers should be slightly below the level of the two ends. The blue-tack end stops tend to stick
The marbles always go onto the flipper from the side, not from above, this makes for a very controlled use of the marble's kinetic energy
The marbles pass through holes in the card to get to the next level down. In this arrangement the top flipper has to be slightly wider than the lower ones.
The end stops on the top flipper are made from bent paperclips, they hold the ends of the flipper to support the cornering force as the marble goes by.
Link to movie
Link to similar thing made of wood
This dispenses marbles automatically one at a time. You have to hold it carefully or the marbles come out two at a time. The length of time the buffer is lifted is controlled by the speed with which the marble traverses the end of the lower channel. Lining the top channel with paper prevents the marbles from jamming if the gradient is a bit shallow. The curved slip of card in the chute ensures the newly-released marble rolls to the other side of the pivot as quickly as possible.
Similar dispenser on YouTube
This flips a marble from one cradle to another
Making the cradles is very tricky, the upper one has a projection underneath that collides with the straw that supports the pivots, thus transferring the marble to the lower cradle. The swinging arms are counterbalanced so they rotate as slowly as possible. With better bearings they can be made to swing through much more than 180 degrees. They rotate in planes at right-angles to each other. So more of them cascaded together could potentially fill a large volume such as a stair well.
read about marble runs
sort of marble run mozart
very complex example
some nice lego creations
I have recently discovered it pays to make plastic bead runs rather than marble runs. Because beads are so much lighter you can try out your ideas very quickly using folded strips of paper glued to (or suspended from) paper structures. The simplest one is a sheet of paper taped to a fridge door with folded strips of paper glued to it obliquely so the bead runs back & forth.
This is a free-standing version
The overhangs at the corners are necessary because the bead runs uphill slightly before going down the slope. The paperclip is just convenient storage for some plastic beads.
Link to movie
This is a mechanised version; it is hand-held, the motor operates a flipper which propels beads to the far end of the paper structure where they hit an oblique end-wall & are deflected sideways. They run down the right-hand side of the structure and in through a side opening just above the flipper.
This is a detail of the flipper: it is made by folding a sticky-fixer round the shaft of the motor
Even with just one battery it can keep several beads in circulation. The advantage of using a single battery-holder is that the leads can be hooked into the motor terminals, no soldering is necessary
This is a round version
detail of the flipper
This one works by blowing
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