THIS PROJECT AROSE out of a desire to add more interest to a canalside dock, in particular to add some height to a rather 2D part of the layout. It is entirely freelance and has its roots in half-remembered childhood constructions in Meccano.

Almost everything has been 3D printed (Wanhao i3+) using PLA filament. I had intended it to be a static model. That seemed altogether too easy and, as I happened to have a couple of tiny motor gearboxes from an earlier abandoned project, I accepted the challenge of trying to make it work.

A search of Thingiverse yielded excellent I-beam girders and right-angled brackets I-Beam which can be scaled to suit.

I started the construction from there having measured the dimensions required. The basic frame was glued together with epoxy, taking great care to keep everything square. The structure was quite flimsy initially, but the brackets and end plates toughened it up. My printer was not big enough to print the cross girders full length, so they are joined in the middle with rivet embossed plastic card plates to strengthen them. Plastic card plates run under the length of the cross girders and support the track. The micro motor/gearboxes (from China via eBay) operate at 3V and at about 30rpm. They are housed in electric motor shells WEG Electric Motor, which sit on a plastic card platform. The motor shells print in pieces, making it easy to screw the motor/gearboxes to the front flange of the shells before assembly. Sitting under the motor platform is a 3D- printed battery holder for two AA batteries. The two switches to operate the crane are attached to an aluminium plate which forms the front of the motor platform and is screwed to the woodwork of the layout, as the force needed to operate the switches (DPDT, biased centre-off) would be too much for a light plastic construction.

Universal couplings join the motors to brass rods which carry the chain winding drums (again 3D printed). The couplings serve to take up any slight misalignment in construction and provide a convenient link between the motors and drums. The truck, wheels, track, hook and pulleys with mounts are again 3D printed.

I find the search results in Thingiverse somewhat scattergun, so I had to be persistent. Sometimes prefacing the search term with ‘railway’ seemed to help. There are plenty of options available. Scaling, cutting and filing allow easy modification to suit.

The chain came from eBay and is connected as shown in the diagram. The two switches allow the motors to be operated in forward or reverse direction and, to my delight, it all worked well. I allowed a little slack in the trolley chain to compensate for uneven winding onto the drums. I think that this might be taken up by inserting a light spring in tension at one end of the trolley. Battery power is fine. In practice the crane will not be operated very much but it is nice to know that it can be.

As with so many model railway projects this is not quite complete. Are they ever? The structure has to be weathered and the motor platform is awaiting a roof and control panel for the operator. The walkway handrail stanchions need to be replaced with something more to scale.

I am not sure what Cowans Sheldon would have thought of this but I am pleased with it.