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The Great Ball Contraption, the ultimate Lego challenge, has been perfected

Of all the things made with Lego, my favorites are invertibly the Great Ball Contraptions. GBCs, as they are know for short, are Rube Goldberg-style machines designed with the sole purpose of moving tiny balls through a circuit. The mechanisms that move the balls through the loop are generally as complex as possible, using clever actions that are reminiscent of the workings of a factory right out of How It’s Made.

This GBC is particularly special. It uses a brilliant design and has the added bonus of being featured in a high quality, well produced video. The popularity of all too many Lego projects is held back by poor video work. That’s not the case here — YouTube user and creator Philip Verbeek did an incredible job this time around, setting a new bar for GBCs and GBC videos.

Verbeek’s GBC 5 uses six discrete modules. Modules are simple machines (like an Archimedes screw) that work together to create the entire circuit. The more modules, the more complex the GBC. Module design is quite varied from one builder to another, but the point is that they would theoretically be able to work together, even though the standards for GBC modules seems to be quite loose.

Verbeek’s creation used about 2500 Lego pieces and two motors, a Lego XL and one for the 9V pneumatic pump. The controlls are provided through Lego’s NXT 1.0, which also handles the counting of the balls as they work their way through the circuit.

Verbeek’s GBC modules don’t all have formal names, but he was nice enough to describe the mechanisms for us (you can see them all in the gallery):

  1. Push: Pushes balls from the left and right side to the middle track.
  2. Accelerator: Shoots balls to the other side.
  3. Splitter: Makes balls go left and right in pairs. Two balls go left and then two balls go right.
  4. Stop-go #1: Stops balls and lets them go by at the right time.
  5. Stop-go #2: Same function, in another position.
  6. Stop-go #3: Same function, in a third position.
  7. Shoot: Shoots balls using a normal Lego spring.
  8. Cardan gear: Moves trolley back and forth.
  9. Tilt trolley: Dumps balls to another track.
  10. Pneumatic scissor lift: Adjusts height.
  11. Pneumatic switch: Controls air flow.

So, yes, it’s a very complex device, but it does its job extremely well. Verbeek’s usages of simple machines — like the Cardan gear, which converts circular motion into linear motion — might seem simple in concept, but as you can see in the gallery images, the implementation of these concepts is much move complex. And then designing a machine from scratch that uses all these mechanisms is certainly the most impressive part of the GBC. Even for the advanced adult fan of Lego (AFOL) the GBC is a huge challenge and time-consuming undertaking.

Now read: Lego contraption is great at moving balls

[Image credit: Philip Verbeek]


  • GBC – Accelerator 002

  • GBC – Stop-go mechanism

  • GBC – Splitter 01

  • GBC – Splitter 02

  • GBC – Accelerator module

  • GBC – Push Mechanism, underside

  • GBC – overview

  • GBC – overview 002

  • GBC – overview 003

  • GBC – ball on rail

  • GBC -basin

  • GBC – controller

  • GBC ball stack

  • GBC – Pneumatic switch

  • GBC – Pneumatic scissor lift

  • GBC – Stop-go 3 – 001

  • GBC – Stop-go 3

  • GBC – Tilt trolley 02

  • GBC – Tilt trolley

  • GBC – Cardan gear 03

  • GBC – Cardan gear 02

  • GBC – Cardan gear

  • GBC – Stop-go 2

  • GBC – spring mechanism

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