Day 21-3 – Great Ball Contraption (GBC) – Chris Pearson

Chris Pearson

Great Ball Contraption


Great Ball Contraption (GBC)

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I started playing with LEGO® as a child and enjoyed the early Technic builds.

Approximately 5 years ago I saw a YouTube video of a GBC which sparked my interest in GBC.

I attended my fist Bricktober in 2016 and saw the first GBC display that Bricktober had and from there I started to build and displayed my first year in 2017.

About the Display

A Great Ball Contraption (GBC) is a machine which receives soccer balls or basketballs from one module and passes them to another module.

A GBC is a group effort – this year we have 6 builders and an estimated 200,000 LEGO® parts.

GBC modules have a lot of moving parts and tend to come brake and drop the balls so its a constant job checking and repairing the modules as we go.

Interesting Facts

There are rules which we generally have to follow, this is so that the modules can feed another builders modules.

The rules are:

  • Each module should have an “in-basket”, and will move balls to the next module’s in-basket, which must be directly in line.
  • The in-basket should be 10 studs by 10 studs (outside dimension) with an 8-stud by 8-stud opening, and should be 10 bricks tall.
  • The front of the basket should be no more than 32 studs from the back of the module. This will allow all modules to be lined up against a wall. The back of the module can be closer to the basket, but not farther.
  • The in-basket should be located on the left side of the module, and output should go to the right.
  • There are no size limits beyond those listed.
  • Each module should be able to accept balls at an average rate of 1 ball per second. Balls can be passed continuously, or in a batch. A batch should not exceed 30 balls.

Set Number

Chris Pearson                     Set Number:  BT2020-213