Sludge Crane

Over the years I have designed and built three different 4mm scale manual cranes using only photographs as the reference. This one is a Tangye 8 cwt Sludge Crane. It was a challenging and enjoyable project, more so because of design difficulties that demanded much thought to find solutions. 

The model was designed in FreeCAD as a kit of parts for 3D printing using the filament layering method (FDM - Fused Deposition Modelling). Various axles and the chain are made from wire. In all there are 34 individual parts to the build. I guess it took about 40 hours to design and build.

I was not sure at the outset if it would be feasible to produce because the reference photographs found in a magazine were not shot from the best angle for scaling and showing details. Fortunately dimension of the upright beams was given and this was the basis for calculating dimensions of most parts. No additional information was uncovered in Internet searches for this crane. Whilst Tangye was/is a notable brand the manufacturer seems better known for hydraulic jacks.

Some of the parts are extremely small and do not lend themselves well to FDM 3D printing as they can be malformed. At about the third attempt at printing these I found that tweaking parameters in the 3D print settings overcame the problem. A couple of other compromises were necessary. These being the beams, which are solid in the model instead of 'U' channel girders in the prototype and the gears where teeth were omitted, being far too small to print with my 0.4mm extruder head. Frankly, it is not noticeable when viewing from normal distance.

The finish was painted using enamel paints. Rust effect was sponge dabbed and a dusting of white, scraped pastels applied whilst the paint was slightly tacky for toning down the finish and highlighting details.

The winding mechanism is static but, the crane can be rotated on its plinth.