Re: Plastic torsion spring



Start here:

http://www.efunda.com/DesignStandards/plastic_design/hinge.cfm


And here:

http://www.profilesmagazine.com/p15/tips_spinal.html

http://engr.bd.psu.edu/pkoch/plasticdesign/living_hinge.htm

If you take this basic hinge and make it narrow and with a slight
curvature it will snap into one of two positions.

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