Step 8 completes the model with the cabin, railing and other small stuff. The cabin is a little too small for a minifigure. The model uses something like 75% of the parts and, crucially, the new parts in it are used only for cosmetic purposes so if you have enough Technic laying around you might be able build the actual mechanism without resorting to dismantling the BWE or buying another set. The driveline for driving, turning and the small conveyer belt are also connected with these parts. Here it’s more obvious. The parts don’t hold tight to the axle but can slide. This allowing some wiggleroom when lowering and raising the big arm.

Step 4 builds the structure that carries the 2 arms. During the build I wondered why there were Technic Wedge Belt Wheel (4185) sitting in different angles at the bottom. There were no belts in the inventory, so I was unclear of their use. Thanks to Evvilspoon, who's also built it, for confirming that it was not just my model that had problems with the 1x1s.

The build – Step 6

After experimenting this morning, I found a simple fix for the latter problem which doesn't solve it fully but does improve things considerably: I am therefore not able to wholeheartedly recommend this set: Personally I think it's pushing the boundaries of what's possible with Technic, particularly the Power Functions system, a bit too far and the model has suffered as a result.

Now, by this point the model has become so big that it no longer fits on my regular photography table so I was unable to take more photos until I had something bigger. The following pictures are therefore taken with different lighting in a different 'studio' and to be honest I am not that happy with them but hopefully they will serve to illustrate the finished model. It's somewhat front-heavy so there is a bit of a tilt on the body which results in the vertical frame not being exactly vertical. It doesn't seem to interfere with operation though. You can also see in this picture the three axles that transfer power from the upper part of the machine to the lower part. They are connected using 'slip axles' which means it is easy to disconnect them for testing purposes.

Details

So, how does it work? Quite cleverly as it happens, but unfortunately the mechanism is buried deep inside the machine so is impossible to photograph without a major dismantling. (Yes, I should have photo'd it before finishing it, I know...)