This monster was born during the December holidays 2018, and completed early 2019. Holiday monsters generally require a simpler approach to construction than when at home with all my toys and therefore have their own challenges. This one started by searching the beaches for inspiration, which in this case came in the form of some bones. The bones dictated the general shape of the monster, resulting in a big bellied flapper. This lent itself to having space for lots of passengers. So then the family trip idea was generated.
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| Monster birthplace taken during first moments of 2019 |
Leading up to the holiday I had been searching for some group of people that would have something in common with moving models. During this search I came across whirligigs, which are generally simple models powered by wind driven propellers, and which would find a home on top of a post box, if there were still post boxes. As this seemed to originate in America in the depression era, I guess they could have ended up on post boxes. Anyway I thought it should have a propeller and not be driven by the wheels, as I have generally done in the past. So the idea ended up having a long central shaft with many cranks. The were to drive the flapping wings and small family. In this case the pilot (representing driver), and 3 passengers. Only one focused on the road ahead. The rest having animated discussions in different directions. During the holiday I managed to get the wire work completed, with the motion basically established.
The post holiday construction took advantage of the home advantage. The wings are covered with parachute silk and sealed with water based varnish to give a semi-translucent finish. Details are added with craft paint and lots of colours. The final finish is covered with gloss artists varnish to bring the colours out.
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| The casting process in the back yard |
For this monster I carved molds for the wheels out of .engineering plastic which came from some rapid prototypes which were machined decades ago. Using these molds I cast the wheels using lead recovered from wheel balancing weights. The molds generally allow 6 to 8 items to be cast before they are damaged too much from the heat. The final wheels have unique characteristics due to the gradual degradation of the molds. The closest two were selected and had bearings soldered in. These were made from sections of a small diameter copper tube. The wheels were then painted as a variation to my normal plain finish.
The propeller was the fun bit. It is made from wood ripped from some old Oregon pine beams. This seems to have proper scale grain. Six blades were chosen in an attempt to make it wind powered, but the resistance was too great. At least it looks interesting. The paint job is done to increase the blades visibility when turning. The propeller drives a reduction planetary gear box to get a realistic propeller speed without having frantic passengers in the back. The planetary gearbox was printed from PLA using a low cost 3D printer. The planetary gearbox design was found on thingiverse and is printed as a single unit. With a little bit of effort and some grinding paste it ends up moving smoothly. The overall result is very surprising. The planetary gear is mounted within a steel ring with copper tubes silver soldered onto the ring for the wire interface. The gears are self supporting (using a herringbone gear), so that the propeller can be mounted directly to the center gear without additional hardware.
A final view from the top shows a rather plumb monster with low center of gravity. The spreading waist line may touch a sensitive point?
