Friday, February 17, 2012

Robotic Snake




















There was only one last large flat sheet of dural Hexaflex left out of 10 which had been laser cut.

I was scheduled to go onto our local TV station to talk about the invention. I really needed a smart, good-looking prop. The laminated card prototypes of earlier days had been handled so often that they were now falling apart. Okay ....shoulders to the wheel and all that...... so I went through the whole forming process again and made that last flat sheet into the largest expanse of Hexaflex so far made that had some spring in it that allowed it to stay mostly in a fully folded condition.





I rolled it up into a cylindrical shape and marvelled at the way that it lap jointed beautifully into the three different aspects of nanotube forming.




It reminded me of a snakeskin .


I researched "snakeskin" and discovered a thriving interest in making robot snakes. Ah! If only one could make a snake that could move like a snake instead of the ungainly efforts so far demonstrated by the state of the art.
 So now I think I've found the solution..... ABS was a good material for strength and the acrylic prototypes that were printed demonstrated a really rigid flexing that ABS would display. That was a problem to me, insofar as that it wasn't really emulating the flexibility that a sheet of hexaflex made from cardboard gave me. This was my technical summing up which described the situation:



"So now we have the finished CAD prototypes. They have been 3D printed in acrylic. They are fragile and break easily but the detail is fine and exact as it has a print layer thickness of 16 microns (0.00063”)
ABS requires a different method of printing called Fused Deposition Modelling. The prototypes have been designed to be made from ABS plastic which is much stronger than acrylic but unfortunately does not hold as much detail as it has a print layer thickness of 40 Microns (0.0016”)
This may cause a deterioration in the fine detail of the bump and hollow which give the tiles the ability to click together.
We have choices:
·        Make the bump and hollow bigger.
·        Remove the click factor altogether
·        Ignore and go to plastic injection molding and trust that the detail is going to inject exactly as CAD design
·        Change the material maybe a more flexible type. I’ve called Emil and he thinks that nylon would be perfect in terms of flexibility and hard wearing. It comes, I believe, with a 16 micron print layer thickness. Emil will get us a quote from Protomold.com. He has no supply as yet of  nylon…to do some experimental prints …..may take 3 weeks. This choice of materials may well be the answer to the flexibility that I’ve been looking for in the tiles. It’s worth the wait IMHO"
E
Everything seems to working out whether I realise it or not...lol