I have a product: a wristband with

[Natalia L.]

I have a product: a wristband with a tether. The other end of the tether would be attached to objects of different weight. Based on how much I want the tether to extend under specific weights, i came up with the spring constant of 0.41 lb/in. I ordered the stainless steel spring with the given spring constant (attached). Unfortunately, when the weight exceeds the maximum load possible (3.1 lb), the spring will start to deform plastically (will not go back to its original form). So, i wonder if there is a construction material so that the spring/coil has the given spring constant AND a large maximum load possible (like silicon or rubber coil)?

 

[btrueblood]

Could you put a rigid link down the middle (or the outside) of the spring to stop it from deflecting further when it has reached its maximum deflection?

 

[Natalia L.]

Could you show me a google picture or drawing of what you have in mind?

 

[EdStainless]

The other option is to go to a compression spring. then when overloaded it simply bears on itself.
There are designs intended to be used like this.

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P.E. Metallurgy, consulting work welcomed

 

[IRstuff]

Garage door springs from ye olden days had an internal retainer that prevented the springs from bouncing around the garage and killing someone if the spring broke, so similar idea. The retainer would essentially be two chain links that would slide over each other in the compressed spring state and extend out when the spring was stretched.

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[FACS]

I have a set of keys on a retractable string. I can hook it on my belt.

The string is only so long, and it will stop when I pull my keys out all the way.
When I let go of my keys, the string pulls the keys back, and the string coils up in a little housing.

So, put this housing on your wrist band.
Run the string through the middle of the spring.
Attach the string to whatever you attach the spring to.
The string will add more spring constant so you will have to re-size the spring you are using.

The string will stop the spring from extending too far and yet it will allow everything to expand and retract.