Friction Part II: Cantilever and Supports

While friction is the enemy, it is also what holds Lego bricks together. Without any glue or screws to hold things fast, the Lego Astronomical Clock design must account for forces that want to separate bricks.

Lego bricks hold together through the stud and tube design. The tubes are slightly larger than the space between the studs, which deforms and applies friction when two bricks are joined. It takes a little force to pull apart two bricks.  The more studs that are connected (like on a 16x1 beam) the more frictional force there is holding the bricks together.

The Lego Astronomical Clock is designed to rest on a shelf with the pendulum and the main driving weight hanging over the edge. This requires Lego beams to support a lot of weight without pulling away from the base. For the main weight support, two 16L beams ensure a high number of studs connect the beam directly to the base. The long beams extend past the edge of the base plate to support the string reel holding the main weight.

For the pendulum support, the cantilever knife-edge pivot is supported in the back with a lift arm to hold the bricks together. Two additional lift arms support the pivot structure by forming right angles with the base. The pendulum pivot cannot fall off the base plate without taking all the other support and cantilever bricks with it. 

Friction is our friend.