It has never been easier to build a complete Great Ball Contraption (GBC) loop yourself! This GBC is entirely built using only parts from the LEGO 42168 John Deere 9700 Forage Harvester set and can be referred to as Alternate Build of the 42168. When building this GBC it makes sure you master the GBC building techniques and tricks so that you eventually also can build your own GBCs. The whole machine is powered by hand on default but can easily be upgraded with any LEGO motor (more information in the building instructions).
This GBC is established in collaboration with Noah de Lange, Berthil van Beek, Kris Bollen who share all the same passion what we have for building great ball contraptions.
Meet Raaf
Bricknerd (a LEGO news outlet) challenged us (together with Noah de Lange, Berthil van Beek and Kris Bollen) to make a GBC from the small LEGO 42168 John Deere 9700 Forage Harvester set. Due to the very limited parts selection it was indeed a good challenge where everyone contributed ideas from their own expertise. We had a blast designing it together and in the end we accomplished the goal of making a nice functional GBC which is also very satisfying to look at. Read the story on how this GBC was created
The GBC 61 Raaf is the perfect addition next to your other GBC modules. It features an input bin, an action and an output ramp. The input bin can hold many GBC Balls. To prevent GBC Balls getting stuck there is an Agitator Whip on top which makes sure the GBC Balls go left or right to the lift mechanism. There they wait for the lift arm to pick them up. In the situation that the agitator becomes blocked, an inline slip clutch will prevent the module to break apart.
The main mechanism is a rotating lift arm with 2 ball forks on it, both mounted on the outer ends of the lift arm. In a fluent motion these 2 ball forks rotate in parallel to pick up a GBC Ball from the input bin and pushes it off at the top.
Note that the GBC 61 Raaf only works correctly when rotating the handle clockwise.
As mentioned before, the GBC Balls will be pushed off at the top, where the GBC Balls can roll onto the next GBC module in line.
With a simple switch you can redirect the GBC Balls into the input bin again so the ball loop never ends.
The gear reduction is cleverly done by using all the left over gears and a clever assembly of beams and supports.
By default the GBC is powered by hand but you can motorize it. In the building instructions we have carefully explained how to do this.
You can easily connect this GBC to all our other GBCs to make the loop even bigger. More information in the building instructions.
Fun Fact
So many gears in this LEGO set. But what to do with them? On the first 2 days (out of 6 days) we brainstormed with the team on various options and mechanisms. Seeing and feeling the parts in front of us gave us many good ideas but only one idea stuck till the end. We really wanted to use as many gears as possible and I think we succeeded. The tricky design challenge for this GBC was to get the GBC Balls on top of the lift mechanism in a reliable way. This turned out to be more difficult than expected given the limited part count. We also experimented with many different agitators until we tried to use the whip element. Very unusual but this turned out to be perfect. We went through many variations until we landed on this final design :)
Bonus Fact
Meet Raaf!
Raaf (named after raven in Dutch) is born out of the left over pieces from the LEGO set. Uhm that is not entirely true actually…
Raaf was born in the beginning of the design process by just messing around with the parts. But everyone loved him so we did our best to keep Raaf alive during the rest of the building process. It almost happened that we needed to sacrifice Raaf completely as we needed a certain part from him. Luckily we succeeded in keeping him alive by thinking outside the box and finding another solution for a problem. Raaf is here to stay and he has so many looks. What look of Raaf do you enjoy the most?
-
- LEGO 42168 set
-
- GBC 61 Raaf – 42168 Alternate Build
Building Instructions Preview
Preview
See the building instructions previews on the left or simply try these free building instructions by adding them to your cart.
Upgrade your GBC 61 Raaf
In the building instructions is explained how to easily upgrade the GBC 61 Raaf with various parts.
Power & Automate
How cool is that!
Learn more!
Get the accessories
We have GBC Balls, handy electronics products and fun accessories available. Take a look at all our accessories!
The GBC 61 Raaf all over the world
Upload today & Check all other Fan Builds
Peter Podhradczky –
Super sada ale trochu sa mi to pokazilo v tom ked to ozubené koliesko malo zapadlo do tej hnedej veci!
mysteaka –
Another wonderful opportunity for my child and me to learn new mechanisms. I appreciate that PV-Productions provides this instruction for free and lets us try it before the associated LEGO kit gets discontinued. My favorite part was that this module has two different functions from other GBCs available at PV-Productions for free. Every time we enjoy PV-Productions’ GBC, we discover new technologies! GBC 61 Raaf is compact, so it’s easy to carry everywhere and connect with other GBCs. And it’s not just a GBC: my child’s favorite part is Raaf himself, especially his big eyes made from gearwheels.
Szilard Gyalay –
I cannot pass a free build. The great things about most of the free Builds is that the Lego set is always a very affordable one. As for this build it only took a couple of hours and having the set will allow to make it fast . Fine tuning is easy . As always a great introductory build. Thanks PV-Productions!
here is my video: https://www.youtube.com/watch?v=sQx_LyzBzT8