Great Balls of Fire

OK, so when I last wrote I was preparing to take my first, faltering steps into the world of Great Ball Contraptions, or GBCs. I'd found instructions online to a GBC which could be constructed using only the elements contained in a single Technic set, 42049 Mine Loader, and prior to cannabalising the parts I'd built and reviewed both the Mine Loader and the alternate build, a Rock Cutter.

My next job was to disassemble the Rock Cutter, after which it was time to get to work on my first GBC. I had initially planned to reverse engineer the GBC, which was designed by Great Ball Pit, from a video clip but I ended up paying to download a set of instructions instead which, as it turned out, made my life a whole lot easier. The download, which is in .pdf format, consists of a total of 62 pages and you can see a full listing of the content in the screengrab below. As well as a 54-page building guide the document also incorporates other content including hints for fine-tuning the GBC mechanisms and instructions for upgrading the module with Power Functions. The building guide is fairly easy to follow; at each stage the parts you need to add are highlighted in pink, and the build is logically sequenced.

I was about a third of the way through the build when I took the photograph below. The GBC module has been designed to be mounted onto a trailer, and the trailer chassis is pretty much done by this point. A pair of wheels will later be attached to the axle that you can see in the foreground, while the various gears embedded into the chassis are part of the mechanism that makes a single cylinder move up and down in the chassis-mounted engine block when the GBC module is activated. The stickers that you can see here and in subsequent pictures are a reminder that we're using recycled elements from a donor 42049 Mine Loader set, and they don't have any significance with respect to the GBC module.

With the chassis complete it's time to get to work on the section of the GBC which is responsible for moving the balls (below). The mechanism consists of a series of sweeper arms which pass the balls along the line as they rotate. The arms obviously need to work together in perfect harmony to make this happen, and in order for the arms move in unison they're connected underneath via a system of gears. Timing is critical - one sweeper arm can't pass the ball to the next unless the rotation of the arms is carefully coordinated - and for this reason specific instructions are provided to ensure that the sweeper arms are correctly positioned relative to each other.

Another important part of the module can be seen on the left side of the picture above. A black 1 x 6 Technic link connects the spindle of the first sweeper arm to a pivoting structure; as the spindle turns it rocks the structure backwards and forwards, which has the effect of feeding balls from the "in-basket" to the first sweeper arm in the finished module.

You can see how everything fits together in the pictures above and below which show the completed GBC module from the front and the back. The GBC mechanism is activated by turning a crank which is located to the left of the wheel in the picture above. Once the balls are swept to the top of the slope by the arms they're 'recycled' along a rear return channel and roll back down into the in-basket, thus creating a perpetual loop. The light bluish grey exhaust pipe element at the top of the slope diverts the balls down the return channel, but if you want the balls to be transferred to an adjacent GBC module instead then the exhaust pipe can be removed and the balls will then drop off the end of the conveyor and into the in-basket of the next module.

You can motorise the module quickly and easily by replacing the hand crank with a LEGO Power Functions motor. I used a standard XL Motor powered by a Battery Box containing six rechargeable eneloop AA batteries and you can see the result in the video clip below; if you're having difficulty viewing the embedded video clip then you can watch it here instead.

Occasionally the ball at the front of the queue needs a nudge from one of the returning balls in order to launch it onto the conveyer, but otherwise the mechanism runs smoothly and the balls are quickly and efficiently whisked up the slope. Watching the module operate is actually quite hypnotic, and it's certainly given me a taste for more. There's still the issue that I don't have many loose Technic elements, but having now built a GBC with the aid of instructions I at least have a better idea of what I'll need in order to build one of my own design and I've also picked up a few techniques that I can potentially make use of so overall it was a valuable learning experience.

If you'd like to build this GBC then you can purchase instructions from here for €9.95. I don't have any financial interest in the sale of these instructions, incidentally, and I paid for my own copy.

Mined Out

One of the great things about the LEGO hobby is the sheer number and variety of niches to be found within it. Although I entered the fray as a big LEGO Star Wars fan, my areas of interest have expanded since then to encompass Modular Buildings, constructing my own MOCs, collecting various other LEGO themes and even dabbling with the odd bit of Technic.

One niche that I haven't previously dipped my toe into, however, is Great Ball Contraptions, or GBCs. GBCs are machines built from LEGO and usually powered by LEGO motors which transport small balls from one place to another. Multiple GBCs are typically chained together, with balls being passed from one GBC module to another, sometimes over considerable distances. In order to facilitate collaboration between GBC builders so that their modules are compatible with each other, a GBC standard has been defined. This standard legislates for various factors such as the size and location of a module's 'in-basket' and the rate of ball flow into the machine, amongst others.

I'd been largely oblivious to the GBC scene until recently when a GBC discussion thread on the Brickset Forum caught my eye. Particularly interesting were postings which linked to a selection of spectacular GBC modules such as the Strain Wave Gearing GBC Module (above) built by akiyuky who was also responsible for the incredible collection of GBC modules that you can see here. I was so impressed that I decided I wanted to have a go at building a GBC myself, but where to start? I've built a few Technic sets, for instance this one, but have never built a Technic MOC. Also, pretty much all of my Technic elements are tied up in official sets, so I initially wasn't sure how best to proceed.

Thankfully the community came to my rescue in the form of a posting by Brickset Forum member greatballpit who linked to this video that he'd posted on YouTube. The video showcases a fully functional GBC module that can be constructed in its entirety using the elements contained in just one recent Technic set, 42049 Mine Loader. I initially assumed that I'd need to reverse-engineer the build by studying the video clip, but it later transpired that instructions are available to download for €9.95 so I decided to take the plunge, pay the money and make my life a whole lot easier. In addition to getting me started in the world of GBCs, the project would also give me the perfect excuse to review the mine loader set, an official LEGO offering that I hadn't previously paid much attention to.

The front of the box (above) showcases the finished mine loader model which is a decidedly odd-looking vehicle - I did a quick internet search and couldn't actually find its exact real-world equivalent, although Caterpillar do manufacture a variety of underground mine loaders which appear broadly similar apart from the attachment at the front. Technic sets characteristically feature an alternate build which can be constructed with the elements contained within the set. In the case of 42049 the 'B' model is a rock cutting vehicle and this is shown on the back of the box (below).

The box opens via a couple thumb tabs on the left side, although as usual I ignored these and instead carefully slid a knife under the seams and opened the left side, thus minimising damage to the box. The box contains four unnumbered bags of elements, three instruction booklets and a sticker sheet (below). There are also four huge rubber tyres loose in the box.

The mine loader is the larger of the two builds and has two instruction booklets as against one for the rock cutter. Both mine loader booklets have front covers which are identical apart from the booklet number in the bottom right corner.

I seldom build Technic. It's therefore not surprising that when I do I should encounter elements that I haven't seen before. This time it was red 6L and yellow 7L axles that caught my eye, although it turns out that these have been around for years and have appeared in multiple sets. Genuinely uncommon elements appearing in the set include a yellow Technic 3 x 3 T-shaped thick liftarm which is only appearing in a set for the tenth time in this colour, and a light bluish grey large Technic turntable base plus its black large Technic turntable top counterpart, both of which have only appeared in a total of 10 sets to date.

In terms of notable features, the build incorporates a 2-cylinder engine; it's actually not the first time that I've built a LEGO Technic engine but I still find it impressive the way that the LEGO crankshaft smoothly drives the pistons in the engine block. The crankshaft also attaches to a flat silver 8 blade propeller which represents a cooling fan and which has only previously appeared in seven sets in this colour. By the end of the first instruction booklet we're well beyond the halfway point in the build (below).

With the bulk of the internal structure and Technic mechanisms already completed, much of the remaining build consists of predominantly cosmetic details. The mudguards behind the front wheels consist of yellow Technic curved 3 x 6 x 3 panels which are only appearing in a set for the third time. These are decorated with black and yellow striped warning stickers and provide the attachment point for bilateral twin headlights. The driver's cab bolts on to the left side of the vehicle and includes a single seat which is made up of a couple of blue 2 x 4 L-shaped thick Technic liftarms. A single exhaust represented by a light bluish grey vehicle exhaust pipe with Technic pin emerges from the left side of the engine, and a couple more of the yellow Technic curved 3 x 6 x 3 panels are used to create the corners of the rear bumper which also incorporates a pair of trans-red tail lights.

The build is nearly complete now. An aerial, represented by a flat silver rapier, attaches just in front of the engine, after which the four wheels with their huge 62.4mm tyres are attached. Finally a red drum, made up of a pair of stickered interlocking red 3 x 5 x 8 cylinder halves which are exclusive to the set in this colour, is assembled and we're finished (below).

I asked my ten year old what he thought of the finished build and I have to report that he wasn't particularly impressed with the look of it; I'd have to agree that it's rather underwhelming from an aesthetic point of view. The build does however incorporate a number of functions, and all of the mechanisms work well.

The large Technic turntable I mentioned earlier connects the front and rear sections of the vehicle. Turning the small black gear next to the cab rotates the turntable; this pivots the entire front section and thus steers the vehicle as you can see in the picture below. Meanwhile, pushing the vehicle forwards or backwards causes the pistons in the engine block to smoothly rise and fall, and the cooling fan at the back to rotate. At the front of the vehicle the claw can be raised and lowered; it's in the fully raised position in the picture above, and the lowered position below. The claw can also be closed and opened so as to grab and subsequently drop the red drum; this is accomplished by rotating another small black gear which is located just in front of the engine. The gear connects to the claw via a long axle assembly running almost the whole length of the vehicle.

With the mine loader completed and photographed it was time to take it apart in preparation for building the 'B' model. One of the reasons that I've struggled to love Technic over the years is the misery of deconstructing the builds, which is both time consuming and a cause of physical discomfort. Thankfully the mine loader is modestly sized so taking it apart didn't take too long, although as ever it was not a comfortable experience for my fingers.

The 'B' model, a rock cutter, is another curious-looking vehicle and a quick online search didn't reveal any real-world examples of machines that looked remotely similar. Like the mine loader it incorporates a 2-cylinder engine, with the pair of red cylinder halves which were previously used to fashion the drum being repurposed as engine covers that wrap around either side of the engine block. The turntable assembly, previously utilised as a steering mechanism for the mine loader, is incorporated into the boom of the rock cutter.

Attaching the boom doubles the length of the vehicle and makes it predictably unwieldy. Despite this, the weight of the body ensures that the centre of gravity is far enough back for the vehicle to be nice and stable, although like the mine loader it's a decidedly strange-looking beast. Following completion of the rock cutter there are 57 elements left over, of which 11 are spares. The rock cutter therefore utilises more than 90% of the set's total of 476 elements.

Function-wise I found the rock cutter to be more interesting than the mine loader. The vehicle can be steered by rotating the prominent tan gear in front of the engine which turns the front wheels, and similar to the mine loader the pistons in the engine block smoothly rise and fall when the rear wheels rotate. The boom can be raised and lowered by turning a crank on the right side of the vehicle, and unlike the claw at the front of the mine loader it has a substantial range of vertical movement. As you can see in the picture below the orientation of the blade can be changed; a pair of red bushes are attached to an axle just above the turntable, and turning these bushes rotates the turntable which changes the angle of the front section of the boom and hence the blade. Finally, you can spin the blade itself by rotating the tan gear at the base of the boom.

So that's both the 'A' and 'B' models built, then. Overall, while neither of these strange-looking vehicles will ever win a beauty contest, they were both enjoyable to assemble. Furthermore, they both manage to cram in a fair number of functions, all of which operate smoothly and reliably.

42049 Mine Loader was released in 2016 at a price of £29.99 / US$49.99 / 39.99€. You may struggle to find this set at retail now, but at time of writing new sealed examples can still be acquired at or below the RRP over at Bricklink which is where I bought my copy from.

Right, now to disassemble the rock cutter in preparation for my first attempt at building a Great Ball Contraption. Check back in a couple of weeks to find out how I got on....