It has never been easier to build a complete Great Ball Contraption (GBC) loop yourself! With over 3300 parts, 500+ pages of building instructions and a footprint of 100 cm (40 inch) by 60 cm (24 inch) and a height of 36 cm (14 inch), this GBC is the biggest, most epic GBC we have ever created so far. It is way bigger than the original LEGO model and it features multiple GBC modules which all work together in harmony to make a full loop so the ball flow will never end. This GBC is entirely built using only parts from the LEGO 42055 Bucket Wheel Excavator set and can be referred to as alternate build of the LEGO 42055 Bucket Wheel Excavator set. When building, this GBC 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 one LEGO motor which comes with the LEGO 42055 set.
Your turn to take control
Ever wanted to have control over your own factory? Now it is possible with our interactive GBC 21 Mine Factory. This Giant factory transports, lifts and shakes the GBC Balls around as never before in completely new ways and fully automatically! With 7 original GBC Modules this factory can handle even the biggest loads of GBC Balls!
The GBC 21 Mine Factory also features a clear IN and OUTPUT so you can easily put this GBC in a bigger GBC Layout. How sweet!
GBC 21 Mine Factory – 42055 C Model Building Instructions
A Wide Conveyor Belt Module takes up to 7 balls and guides them via an advanced ball guidance track system to the Rotating Dual Output Pump Module. As the name suggests this module has 2 outputs between which the GBC 21 Mine Factory will complete automatically, fully mechanical, switch by rotating the entire platform of the module by 90 degrees back and forward. Manual operation is also possible by controlling the gearbox yourself. The pump itself works by inserting a new ball in the bottom and pushing out the top ball through the output.
Going straight forward in the direction of Output 1, the Rotating Dual Output Pump Module will bring the balls to the Rotating Shifting Table Module which mixes and stirs the balls up really good. We have designed the table surface in such way so there are extra holes on the top which allows you to create your very own table layouts. Use the leftover parts of the LEGO Set to create fun obstacles and put your own creativity into play!
When the balls are shaken up good enough they will finally find their way to the center hole in the table and exit the module. This brings them to the Bucket Wheel Shovel Module. We create an artificial, highly precise mountain side where the buckets can shovel the balls up from. When on top gravity will help emptying the shovel buckets and guide the balls to the Long Belt Module. This module will in rapid speed lift the balls away and bring them to the other end of the GBC 21 Mine Factory. On top the balls will drop into an advance and highly flexible Ball Return Arm Module which guides the balls back to e.g. the Wide Conveyor Belt Module, Obstacle Table Module (or any other input you direct the arm to). A rotating mechanism will automatically move the main arm back and forward. Using an ingenious scissor mechanism, which is attach to the main arm, the sub arm can rotate in multiple new directions. You can control if the arm should move automatically or stand still by controlling a gearbox on the side.
When the Rotating Dual Output Pump Module rotates with 90 degrees the balls will be guided to the second output which brings them to the Obstacle Table Module. You can play with the obstacles on the play field to make it unique. After the balls passed all the obstacles they are guided back to the input of the Wide Conveyor Belt Module to go over the loop again and again and again;)
Fun Fact
Designing GBC Modules from existing LEGO Sets is really complex. To connect them all together in a loop and complete the drive system with correct speeds is of a whole new level ingenuity. The GBC 21 Mine Factory is no difference in this but we succeeded again. For the drive system we almost used all the gears that come with the LEGO set which is also double the amount of GBC 15 Mining plant, also a LEGO 42055 set.
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- LEGO set 42055 Bucket Wheel Excavator
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- GBC 21 Mine Factory – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 Mine Factory – 42055 C Model Tilting Turning Table
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
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- GBC 21 – 42055 C Model
Gear up your building skills
While building the GBC 21 Mine Factory you will learn basic engineering at its best like gearing, forces, sturdy constructions, automation, cool mechanism like the scissor mechanism, the rotation switch mechanism and so much more!
The whole GBC is split into different parts/modules which are assembled together during the built. Ideal for working in groups as each builder can work on a module sub assembly and later click everything together. Because of this construction and flexibility it is also always possible to separate the modules again and make your own unique configuration.
It is possible to move the whole structure at once when you hold it right. However, when moving the GBC, we advise to place the GBC on a solid plate or to disassemble the GBC in separate modules again. Footprint of the GBC 21 Mine Factory: 100 cm (40 inch) by 60 cm (24 inch).
We have made it easy to create your own in and output according to the GBC rules. Simply rotate the flexible Ball Return Path Module in any direction you want a bridge the gap to the next GBC Module. In this way you can also easily connect this GBC to all our other GBCs to make the loop even bigger. More information in the building instructions.
Building Instructions Preview
Preview
Try before you buy. We completely understand. See the building instructions previews on the left or try one of our free building instructions.
Upgrade your GBC 21 Mine Factory
In the building instructions is explained how to easily upgrade the GBC 21 Mine Factory with various parts.
USB Power Box
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Martijn Laan –
This was fun to build and the design is very clever but ultimately I wouldn’t recommend it for beginner builders. It simply isn’t reliable enough, things like gears falling off because they’re not properly secured shouldn’t be acceptable to the designer. Instead of adding yet another module and running out of parts, proper reinforcement should be done first.
PV-Productions –
Hi Martijn, Thank you for your honest review and glad to hear you liked the build! Due to tolerances and wear/tear on peoples LEGO sets/parts it can be that some connections are not a sturdy as they should be in a certain situation. A simple fix is to replace the connection in questions with similar parts and recreate the connection again. Most likely you have experience this yourself while building other LEGO sets as well.
If you still have any problems getting the GBC to work reliable you can always get in touch with us and we are happy to help you getting things up and running again. You can do this via our support desk: https://pv-productions.com/support/
Adam Schuman –
Paul B –
Just finished the GBC 21 Mine Factory 42055. WOW what a wonderful build. It ran great right off the bat. When I added more balls however I had to make a few adjustments. Can’t wait to try out your new Spirograph plans. I have made a similar Harmon-o-graph that works with two swinging pendulums and opposing arms that hold a pen. Tot ziens!
Kornelius Boersma –
Liked the build, overall clear instructions. Only the final page does not show where the conveyors should go (although it is obvious).
Getting it to work is a bit more tricky. Some of the challenges I came across:
– balls got stuck on the white table (fixed by increasing the angle)
– wide conveyer got stuck on the carrier beam (connect with a shorter connector: part#6013938)
– balls dropping of the high conveyor (added a small side fence to catch the wayward balls)
– gears dropping off on bucket wheel and at the rotating ball lift (torque makes the gears move sideways)
– balls get stuck in the buffer of the ball lift (modified by making the opening smaller; only one ball fits at the same time: this helps to stack also in the slide towards the buffer rather than bridging off at the transit poit)
Every run is still fun though.
jmonks0633 –
Despite being fairly new to Pv-Productions, and a fair bit of mistakes from time to time on my side, I’d say that this GBC has been an absolute blast to make and this is definitely a hobby that i would like to expand on.
Big thanks to the Pv-Productions community and their help center
Jean-Christophe Boillat –
Wonderful modell. My son spent a very nice time building it.
The instructions good be exported with a better resolution and without a white frame all around. In that way it would be much more comfortable (larger) to view on a pad as the instructions are not printable.
hhk –
This was my first time building a GBC. It was awesome! Can’t believe someone came with up this. When it was done I had to tweak some things to make it run smoothly, but no big problems. Love it, keep up the great work!
Theo Bosveld –
I have built this with my son. We had great fun! Fantastic and clear instructions. We tweaked a few points to make it run more smoothly.
Thank you for this!
lego1 –
THANK YOU!!!
It has been my second GBC Instruktion for 4255, and it is even better than the first one I got.
I really love to build them.
GREAT!!!
Ulrike
matthewhearne –
First time building a GBC. Can’t believe that someone could actually come up with such a machine only using parts from an existing set. Absolutely incredible achievement .
The instructions are superb and very professional. Easy to follow (there are a lot of steps!).
The build was detailed, intricate and very interesting. Loved that it was broken down in to separate components so I could build each part over a night, and then spend a while putting it all together and tweaking it to get it working nicely.
Only issue I had with the build that took me a while to work out was on the lifting conveyor, you have to make sure the three cogs (top and bottom) are all aligned the same in their rows, otherwise the track doesn’t quite site correctly. And you don’t put the track on till the last step so by that time you have the whole thing built and I had to dismantle a section to sort it out (maybe put a note in the instructions to check this?).
Thoroughly recommended and hoping to get the GBC 15 build at some point as well.
Everyone that saw any pics or videos was amazed by the thing.
10/10 easily.
macbril –
It’s been a while since I bought it. I made it today.
It’s a really nice model, I think it would be great if I could supplement it more.
kimshaddick –
this is the first GBC I’ve built. very cool but needs some fine tuning to get working. For instance i had to tweak the locking mechanism on the dual output mudule with something different. highly recommend definitely worth the money
ronaldvanessen –
This is a very nice build.Instructions mostly very easy. After it was build I upgraded a few parts to give at certain points a bit more stifness. The special balls work excellent with this build..I’d say all in all a very nice model.
siju86 –
I had much fun during building this model together with my son. Thank you PV Productions!
edgard1977 –
Nice GBC model. High quality instructions
The pdf downloaded well, unfortunately they were not able to be printed. I can understand the reason, but somewhere they say “print” and it is not possible in a easy way.
That’s my only conclusion. And thanks for your work!
PV-Productions –
Hi Ergard, The stickers and measurement sheet can also be found in the Media Pack :) See also https://pv-productions.com/product/pv-productions-media-pack/
michael1 –
Pros: Fun to build
Cons : Doesn’t actually work how it’s supposed to.
Liked the build and the way the GBC goes together. Bot the execution of the whole model doesn’t really work so well
I spent over 50hrs (after build time) trying to get it to run properly but this is just about impossible with the strain on the gears being too much for plastic and the gears always slipping.
The top conveyor belt works well.
The bucket scope doesn’t as the drive keeps popping off the side.
The tilt table work well.
The rotating ball lift doesn’t work well, balls get stuck, the gear system to rotate it work when it feels like it.
The 3 belt bal lift doesn’t work at all as the strain on the gears feeding it just cause this to stop, and the lego attached to the belts keeps jamming as it comes around the bottom.
Benth –
I love this GBC so much! Had so much fun building this (about 12 hours). Fine tuning also took some time but that’s part of the fun. definitely worth the money!!
taehanminguk1943 –
Sugoooooi!!!
So cool!! Awesome GBC module
Thanks:-)
paweturalski –
Epic model, nice dual pump idea, complex moving table, this is so satisfying to watch
Daniel Rynduch –
Great module. Awesome experience. No matter how old are you, you need this GBC like a water :D
Johan Danker –
In 1 woord: GEWELDIG!!!
In 1 word: AWESOME!!!
Michael Lam –
Very Cool,!
johnruse –
I rate this model as the best GBC I have yet built, and like the automatic switching functions very much.
Great build with excellent instructions and works really well.
John Ruse