Basically you can turn fishing line and nickel welding rods into
a linear actuator that can contract much like a human muscle.
Sorry no update for a while, this one will be kinda long due to the scale of my breakthrough. Found reliable ways to produce both nichrome wrapped and regular twisted nylon muscles from 50lb mono filament. I was able to pair together numerous AAA batteries in order to get the amperage needed to contract a muscle quickly. I found I could contract about 10% in 30 seconds with 9 amps when weighted with about a pound.
My great breakthrough was getting multiple muscles working together because unshielded they could touch and create shorts. I first tried to insulate them with silicone conform coating purchased from amazon. But that failed because it restricted movement quite a lot but may be something I come back to.
I found that if I lined up non-wrapped and wrapped in an alternating pattern the non-wraps would insulate the wraps from each other while being heated by their neighbors. To keep the multiple strands at the same tension I put them under load and then 'tune' then until they all appear the right space apart. Following that I clamp them with a small piece of wood and seal them loosely in plastic wrap. I've included some pictures below. My first attempt was with 3 muscles and is a bit stubbier, my second is much longer and with 7 muscles.
More to come soon!
Well I ended up using all my Nichrome wire last weekend so I had to order more and due to time constraints I do not think this project will be any where near ready for the Hackaday Challenge this year.
My current go forward is to complete a Proof-of-concept robot forearm and hand of limited motion all powered by groupings of twisted nylon actuators and using sweat like evaporative cooling . I was unable to find a suitable waterproofing yet but have ordered Silicon conformal Coating which should work along with my order of additional 36 gauge nichrome wire.
We will see how that goes next week!
This weekend I spent time experimenting with Nichrome Wrapped Hyper Spun nylon actuators. Do do this I follow my regular process of laying out a some 8lb fishing line, under some weighted tension provided by some metal washers. Then I pin some wire of roughly the same length to the nylon with some alligator clips and allowing the hobby motor spin until hyper wound. I found that lightly wetting the nylon with lubricant stopped the nylon from tearing mid spin.
Please enjoy some pictures I took during the experiments.
Also an instructable on building a "Vaporizer Power Box" that I use as a blue print for heating the nickel.