No 8 : Sea Bones

This time it took even longer to get the next blog out. Up till now I have avoided adding music to the videos because I often get irritated by some video soundtracks. My brother pointed out to me that the silent videos tend to lack something (ie. could be boring), and that sound is required. This is my first attempt at providing the viewer with something to do while the video proceeds, and irritating those who don't like random sound tracks.

The sound track was sourced from a generous and talented Capetonian who allows his music to be used with no strings attached under a CC1 licence. He can be found at his website  https://johnbartmann.com. I chose the piece as it has Southern African appeal as well as seeming to convey the feeling of effort while old sea bones tries to progress through the video. I have not got the sync sorted yet, but that can come with time. I'd rather start than wait until its perfect.

This monster was created out of bones which were found on the beach during a vacation. I suspect the original owners of these bones were fish or birds.The bones are joined in the front with some sort of sea shell and lots of white epoxy. In later monsters the glue of choice became super glue mixed with baking powder. This dries quickly and can be cut or sanded to remove excess glue fairly easily. After the skeleton of the monster was defined with bonded bones, the wire work was done to add rigidity and form. This has very simple movement, and only relies on the bones to give it character. The flapping mechanism is straight forward.

The neck and head differ from other monsters in that the head is made of some coral, also recovered from a beach. This has been painted in almost red and black, to hint at a face. The neck gets some shape from an old metal turning off-cut. It has rusted with time which adds some colour. Overall this monsters mechanism is very simple, with the the wheels driving the wings and head via a simple crank.

The driving of the monster in the video was less simple. As the wheels are inside the frame, the wheel driving mechanism developed for the other videos could not couple to the wheels.  A new mechanism was developed using an old low cost electric screwdriver and a custom made right angle drive. The drive is coupled to the wheel axle using a small collet. The drive mechanism had to have a low profile and couple close to the monster, so that the wings did not interfere with the drive while flapping.  The electric motor was driven from a single laptop cell (Lithium Ion). Unfortunately the drive was too fast for the monster, and ended up winding the push-rod around the axle during the far too energetic flapping attempt. To solve the problem a variable speed drive was designed using a ATtiny  processor, power FET and using Pulse Width Modulation for speed control. The speed was adjusted using a small potentiometer. Unfortunately there are no markings on the speed control to set the flapping speed repeatably, so some of the video clips are noticeably quicker than others. This also complicated the selection of a music clip as there isn't a steady rhythm throughout the video.

The top view of the monster shows the simple design. The wings are covered with a cotton cloth (showing that it is an early model). The colours where airbrushed on, with the colour scheme selected to try and give an extra bit of depth.