Ok, so I got bored on a day off of work and decided to get geeky since I couldn't find the info I wanted online anywhere. Here's the results of a very basic test of the point at which a few gauges of wire begin to stretch:
28ga A1: 10-12lbs (1" stretch)
26ga A1: 20lbs (1.5" stretch)
24ga A1: 33lbs (1" stretch)
22ga A1: 45lbs (1/2" stretch)
Now, while there seems to be a pattern to the rise in size of wire gauge and weight needed to stretch it, I want to note that this is a very rough test with a very simple fish scale used to measure static resistance as weight. Also, the length of stretch is far beyond what would be needed for cohesion and a solid bond between the wraps of the coil itself; I am no expert, but I would say roughly 50-75% of the force or maybe less would get to the "effect" we are after. I'll continue to experiment some as I can get to better equipment and ways to test for the effect.
Basically as I understand it, here is a physical demonstration of the adhesion we are looking for:
If you look at a length of rope near a snug knot you can see where the extended length is constricted by the knot itself, and that area that is constricted is made longer when the rope is pulled on and stretched.
If it was pulled hard enough it would stretch permanently or break (this defeats the purpose with wire as it would reduce the diameter and increase the resistance per inch). Here is the fun part, if allowed to pull itself back towards the knot it will expand towards it's original diameter and hold tight (this is why knots like the clove hitch work). It's this expansion as the wire tries to expand back to it's size that gives us the adhesive effect that pulls the coils back onto themselves and holds them solid into whatever shape they are formed into. This is also why it's more difficult to create a coil as stable as a t.m.c. while wrapping wire around a screwdriver or something similar.
My testing got a bit more controlled and I got better results, here's some images for an idea while I get it all written up:
28ga A1: 10-12lbs (1" stretch)
26ga A1: 20lbs (1.5" stretch)
24ga A1: 33lbs (1" stretch)
22ga A1: 45lbs (1/2" stretch)
Now, while there seems to be a pattern to the rise in size of wire gauge and weight needed to stretch it, I want to note that this is a very rough test with a very simple fish scale used to measure static resistance as weight. Also, the length of stretch is far beyond what would be needed for cohesion and a solid bond between the wraps of the coil itself; I am no expert, but I would say roughly 50-75% of the force or maybe less would get to the "effect" we are after. I'll continue to experiment some as I can get to better equipment and ways to test for the effect.
Basically as I understand it, here is a physical demonstration of the adhesion we are looking for:
If you look at a length of rope near a snug knot you can see where the extended length is constricted by the knot itself, and that area that is constricted is made longer when the rope is pulled on and stretched.
If it was pulled hard enough it would stretch permanently or break (this defeats the purpose with wire as it would reduce the diameter and increase the resistance per inch). Here is the fun part, if allowed to pull itself back towards the knot it will expand towards it's original diameter and hold tight (this is why knots like the clove hitch work). It's this expansion as the wire tries to expand back to it's size that gives us the adhesive effect that pulls the coils back onto themselves and holds them solid into whatever shape they are formed into. This is also why it's more difficult to create a coil as stable as a t.m.c. while wrapping wire around a screwdriver or something similar.
My testing got a bit more controlled and I got better results, here's some images for an idea while I get it all written up:
