Giant Tentacle

9/16

For Derby Mini Maker Faire 2016.

Still under construction. More details when it is done. This is an experiment with actuated low-pressure inflated structures, part of some ongoing work with the ever-marvellous Rusty Squid.

In the meantime, here's the first test joint:

Running a quick test:

Here are CAD files for the air valve and the feedback pot arms(the arms need a hinge adding in the other dimension, they do not work well yet)

The plumbing for the air valve is all made from 100mm Manrose ventilation parts from Screwfix and 100mm tumble dryer ducting from eBay. The body of the valve is in a bit of 125mm Manrose ventilation pipe.

Arguably, I should have used 150mm pipe. The valve restricts the flow to less that 1/4 of the area of the pipe at the endplates, and that's probably the most restrictive bit of the system and hence sets the limit on how fast the hinge can move. I coped the 100mm pipes to the side of the 125mm pipe with the aid of an online coping calculator and a printed paper template. And I hand-made a template to layout out the fixing holes and side holes in the 125mm pipe.

Assembly-sequence pictures are here, I hope it all makes sense. Feel free to mail me if it doesn't.

The sewing pattern should be reasonably obvious, just two pointy-ended cuboids which are permanently inflated and two wedge-shaped chambers which are connected to the two sides of the valve.

The blower I used is a cheap 480W bouncy-castle blower from eBay. A smaller blower would probably do, as long as it was designed to run into a stall. There's plenty of spare air supply, so it doesn't matter if the sewing is a bit leaky. The fabric I used was a cheap 4oz PU coated nylon which seemed to work very well.

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