Freely mounted wheel set made of micro-machinable material and method of fabricating the same

A method of fabricating a gear train that includes the following steps:

• a) taking a substrate that includes a top layer and a bottom layer made of micro-machinable material and secured to each other by an intermediate layer;
• b) etching at least one pattern in the top layer and the intermediate layer until the bottom layer is exposed, so as to form at least one first cavity belonging to a first wheel set;
• c) coating at least the bottom of said at least one first cavity with an electrically conductive coating;
• d) electroforming a material, at least in the bottom of said at least one first cavity;
• e) etching a second pattern in the bottom layer as far as the coating of said electrically conductive material, so as to form at least one second cavity belonging to a second wheel set;
• f) structuring a photosensitive resin on the bottom of the bottom layer, forming a sheathing on the walls of said at least one second cavity and at least one recess that flares out coaxially from said at least second cavity;
• g) continuing the electroforming started in step d) so as to fill said at least one first cavity and starting to electroform a material in said at least one second cavity and said at least one recess, so as to form an arbour fitted with a collar;
• h) removing the photosensitive resin;
• i) removing the intermediate layer so as to separate the first and second wheel sets;
• and
• j) releasing the fabricated wheel set from the substrate.