After trying to reproduce the results we had in this post we noticed some problem of repeatability. It was less frequent than the previous but still at a level we couldn’t ignore and that would cause future problem.
After working each on our own during the morning, I met with Alexis, Henri and Ilan in the E-lab/Fab-lab to further investigate the problem.
It turned out that we spent the afternoon testing dozens and dozens configuration. The parameters we changed were : spacing between marbles, marbles diameter, thickness of the plates we put the marbles on, material of the plates, stacking of the plates, using or not using little round metal plates (non ferromagnetic) to try to canalize magnetic field.
We also tried using handmade coils (100 and 200 turns), using a screw or bolts to canalize the magnetic field but it was no use. We achieved some nice results, but when covering the marbles with polish nail on a face (to be able to discriminate both poles easily) the friction would become too important and repeatability would pay the toll for it.
Nonetheless we kept going, and we made the marbles undergo the cooking process at 300°C for 5 minutes again. It turns out that although marbles have nearly lost their magnetic field, enough remains such as the marbles would still be influenced by the magnetic field generated by the coils. This proves to be a promising process and configuration because the remaining magnetic field isn’t strong enough for the marbles to influence each others when spaced by 3 cm.
Here is a video (without the wood plate though) :
Notice that (as intended) only the middle marble is rotating. The configuration here is : coils with the little metal round plates on them, 2mm plexi, marble on the plexi, and 4 mm plexi with holes to lodge the marbles.